D

• D chemical symbol, deuterium.

• 2,4-D see 2,4-dichlorophenoxyacetic acid.

• d symbol, deci-; 2′-deoxyribo.

• d- abbreviation for dextro- (right or clockwise); used as a prefix in the description of a chemical compound.

• Δ delta, capital; fourth letter in the Greek alphabet. A symbol for increment.

• δ delta, small letter; fourth letter in the Greek alphabet.

• D gene segment see diversity gene.

• D-loop a structure produced during the initial stages of the replication of a circular DNA molecule as a result of strand displacement, by the leading strand, of the unreplicated lagging strand.

• 4D meat meat from animals that are dead, diseased, dying or have been destroyed. Usually salvaged for rendering.

• da deca-.

• dacarbazine (DTIC) [d -kahr′b -zēn] an alkylating and antimetabolite, cell-cycle nonspecific antineoplastic agent. Used primarily for treating malignant lymphoma and lymphoreticular neoplasms.

• Dachshund a small (approximately 20–25 lb) breed of dog characterized by its long body, deep chest, and very short legs. A German breed, the name means ‘badger dog’, bred for hunting small game. There are three coat types: smooth (or shorthaired), longhaired, and wire-haired, found in black, shades of brown, brindled, and dappled. A miniature variety (less than 10 lb) is also bred in all three coat types. The breed is predisposed to intervertebral disk protrusion, acanthosis nigricans, cystinuria, and diabetes mellitus.

• Dacie’s fluid a diluting fluid containing trisodium citrate and formalin, used for blood counts, particularly for fish blood.

• Dacron polyethylene terephthalate, a polyester synthetic material used widely for sutures and vascular prostheses.

• dacry(o)- word element. [Gr.] relationship to tears or the lacrimal apparatus of the eye.

• dacryagogue 1. an agent that induces a flow of tears. 2. a lacrimal duct.

• dacryoadenalgia [dak″re-o-ad″ -nal′j] pain in a lacrimal gland.

• dacryoadenectomy [dak″re-o-ad″ -nek′t -me] excision of a lacrimal gland.

• dacryoadenitis [dak″re-o-ad″ -ni′tis] inflammation of a lacrimal gland.

• dacryoblennorrhea [dak″re-o-blen″o-re′ ] mucoid discharge emanating from the lacrimal apparatus.

• dacryocele [dak′re-o-sēl″] see dacryocystocele.

• dacryocyst [dak′re-o-sist″] see lacrimal sac.

• dacryocystalgia [dak″re-o-sis-tal′j ] pain in the lacrimal sac.

• dacryocystectomy [dak″re-o-sis-tek′t -me] excision of the lacrimal sac.

• dacryocystitis, dacrocystitis [dak″re-o-sis-ti′tis] inflammation of the lacrimal sac.

• dacryocystoblennorrhea [dak″re-o-sis″to-blen″o-re′ ] mucoid discharge emanating from the lacrimal sac, with constriction of the lacrimal duct.

  D-01.

  

  Severe dacryocystitis in a Weimaraner with multifocal cutaneous draining tracts. Dziezyc, J., Millchamp, N. Color Atlas of Canine and Feline Ophthalmology. Saunders, 2005.

• dacryocystocele [dak″re-o-sis′to-sēl] hernial protrusion of the lacrimal sac; dacryocele.

• dacryocystoptosis [dak″re-o-sis″top-to′sis] prolapse of the lacrimal sac.

• dacryocystorhinography [dak-re-o-sis″to-ri-nog′r -fe] radiographic imaging of the nasolacrimal apparatus; usually performed before and after injection of an iodinated contrast agent through the lacrimal puncta.

• dacryocystorhinostenosis [dak″re-o-sis″to-ri″no-st -no′sis] narrowing of the nasolacrimal duct.

• dacryocystorhinostomy [dak″re-o-sis″to-ri-nos′t -me] surgical creation of an opening between the lacrimal sac and nasal cavity.

• dacryocystorhinotomy [dak″re-o-sis″to-ri-not′ -me] passage of a probe through the lacrimal sac into the nasal cavity.

• dacryocystostenosis [dak″re-o-sis″to-st -no′sis] narrowing of the lacrimal sac.

• dacryocystostomy [dak″re-o-sis-tos′t -me] surgical creation of a new opening to permit drainage from the lacrimal sac.

• dacryocystotomy [dak″re-o-sis-tot′ -me] incision of the lacrimal sac.

• dacryocyte [dak′re-o-sīt] a teardrop-shaped red blood cell; observed in fragmentation anemia and myelofibrosis, but can also be an artifact. Found in iron-deficient ruminants, including llamas.

• dacryohemorrhea [dak″re-o-hem″o-re′ ] the discharge of tears mixed with blood.

• dacryolith [dak′re-o-lith″] a lacrimal calculus.

• dacryolithiasis [dak″re-o-lľ-thi′ -sis] the presence of dacryoliths.

• dacryoma [dak″re-o′m ] a tumor-like swelling due to obstruction of the lacrimal duct.

• dacryon [dak′re-on] the point where the lacrimal, frontal and maxillary bones meet.

• dacryops [dak′re-ops] a cystic structure the lacrimal duct containing fluid. See also canaliculops.

• dacryopyorrhea [dak″re-o-pi″o-re′ ] the discharge of tears mixed with pus.

• dacryorrhea [dak″re-o-re′ ] excessive flow of tears.

• dacryoscintigraphy [dak″re-o-sin-tig′r -fe] scintigraphy of the lacrimal ducts.

• dacryosolenitis [dak″re-o″so-l -ni′tis] inflammation of a lacrimal duct.

• dacryostenosis [dak″re-o-st -no′sis] stricture or narrowing of a lacrimal duct.

• dacryosyrinx [dak″re-o-sir′inks] 1. lacrimal duct. 2. a lacrimal fistula. 3. a syringe for irrigating the lacrimal ducts.

• dactinomycin [dak″tľ-no-mi′sin] an antibiotic of the actinomycin complex (actinomycin D), produced by several species of Streptomyces; used as an antineoplastic agent.

• dactyl [dak′t l] a digit.

• Dactylaria gallopava [dak-t -lār′e-] a thermophilic dematiaceous hyphomycete known to cause encephalitis in chicken and poults. Called also dactylariosis. Recently transferred to the genus Verruconis. See Ochroconis gallopava and Verruconis gallopava.

• dactylariosis [dak-t -lār″e-o′sis] a fungal encephalitis of birds caused by Verruconis (previously Ochroconis, Dactylaria) gallopava.

• Dactylis glomerata a valuable temperate region pasture grass that contains a lamb growth inhibitor. Called also cocksfoot, orchard grass.

• dactylitis [dak″t -li′tis] inflammation of a digit.

• dactyl(o)- word element. [Gr.] pertaining to a digit.

• Dactyloctenium radulans Australian grass of the family Poaceae. Contains toxic amounts of nitrate when growing in heavily fertilized soil such as that in stockyards, but elsewhere is a valuable pasture plant. Called also button grass.

• dactylogryposis [dak″t -lo-grľ-po′sis] permanent flexion (contracture) of the digits.

• Dactylogyrus [dak″t -lo-ji′r s] a genus of monogenetic flukes of the family Dactylogyridae that infest fish.

  • D. extensus, D. vastator cause an important parasitic disease of the gills of marine and freshwater fish.

• dactylolysis [dak″t -lol′ľ-sis] 1. surgical correction of syndactyly. 2. loss or amputation of a digit.

• dactylomegaly [dak″t -lo-meg′ -le] abnormally large digits.

• dactylus [dak′t -l s] pl. dactyli [L.] a digit.

• daddy-long-legsPholcus phalangioides; see harvestmen.

• DAF decay-accelerating factor.

• daffodil [daf′ -dil] see Narcissus.

  • d. tree Cascabelathevetia (Thevetia peruviana).

• daft lamb see cerebellar atrophy.

• dagging removal of lumps of wool matted together with feces (dags) from the perineal region of the sheep.

• dags locks or staples of wool in the crutch that are heavily fouled with caked feces.

• daidzein an estrogenic plant isoflavone.

• daily pull and dead records a daily account kept in a feedlot of the deaths and the animals pulled out of each pen because of illness or injury.

• dairy 1. a retail outlet for milk products. 2. the feeding and milking sheds on a dairy farm. 3. pertaining to or emanating from an animals or other thing concerned in the production of milk, e.g., dairy goat, dairy cleanser.

  • d. barn standard indoor housing in temperate and subarctic northern hemisphere countries; a common plan is to have animals housed on the ground floor and grain and hay on the top floor from which it is delivered to the animals below; the cows are tied in stanchions and milked on the spot or roam free and are milked in a parlor.
  • d. breeds see Australian Shorthorn, Ayrshire, Brown Swiss cattle, Dairy shorthorn, Jersey, Guernsey, Holstein-Friesian, Red poll, Australian milking zebu, British white, Dexter, Jamaica hope, Milking shorthorn.
  • d. calf calf of a mating between a bull and a cow, both of dairy breeds.
  • d. cow cow of a breed specifically defined as being for milk production, as distinct from a beef or dual purpose breed.
  • d. farmer a farmer whose major enterprise is dairy farming.
  • d. herd includes milking cows, dry cows, heifers (maiden and in-calf), calves and, where needed, bulls. Called also milking herd, dry herd, followers.
  • d. herd improvement programs traditionally a centralized system, usually sponsored by a government or a farmer-owned cooperative, for recording milk yield and quality and assessing the productive status of individual cows. Larger herds now tend to use programs that are on-farm and stand alone within the single business. With both, recommendations are then made relative to culling or mating program for herd and the individual cows. Programs with a central database provide information on which regional or national analyses of performance can be made relative to a multiplicity of variables, such as herd size, parity, production, reproductive performance, culling, breed, times per day milking.
  • d. industry includes the farms, the milk collecting and handling services, the processors, manufacturers, and retailers and the private and government organizations involved in a coordinating or controlling function with respect to the harvesting and disposal of dairy products.
  • d. sanitizers disinfectants suitable for use in an environment and in a situation in which contamination of the human food chain is likely to occur.

• Dairy shorthorn the dairy variety of the Shorthorn breed of cattle. Called also Milking shorthorn.

• dairyCHAMP a computer program designed to aid dairy herd health and production management. Originates from the University of Minnesota.

• dairyCOMP 305 an on-farm computer program devised to participate in dairy herd health management.

• dairying 1. the occupation of being a dairy farmer. 2. the practice of running a dairy farm.

  • seasonal d. breeding the herd as a block so as to have the herd calve when feed supplies are good.
  • year-round d. a management system in which cows are bred to calve so that there is a constant influx of freshly calved cows.

• dairyMAN a dairy computer program designed to aid dairy herd health and production management. Originates from Massey University, New Zealand.

• DAISY acronym for Dairy Information System—a well-known herd health program and dairy information management system. Designed at Reading University, UK.

• daisy flowering plants in a number of different genera in the family Asteraceae. Their flowers are carried in a dense mass in a disc, usually with only the outer ones bearing petals.

  • African d. Seneciopterophorus.
  • plains plover-d. Leiocarpa brevicompta.
  • South African d. Osteospermum.
  • sunflower d. Wedeliaasperrima.
  • tufted burr d. Calotis scapigera.
  • wild everlasting d. Helichrysumargyrosphaerum.
  • woolly everlasting d. Argentipallium blandowskianum.
  • yellow d. Wedeliaasperrima.

• Dakin’s solution [da′kin] an aqueous solution containing 0.5% available chlorine as sodium hypochlorite and sodium bicarbonate; used historically as a local antibacterial and to irrigate wounds.

• DALA delta-amino levulinic acid.

• dalapon a chlorinated acid used as a herbicide; experimentally high doses cause abortions and weak lambs; nontoxic at normal concentrations.

• Dales pony English heavy miniature horse, 14–14.2 hands high, usually black or dark brown, sometimes gray.

• dalfopristin [dal-fo′pris-tin] see quinupristin/dalfopristin.

• Dall sheepOvis dalli; a medium-sized wild sheep.

• Dallis grass Paspalumdilatatum.

• Dalmatian a medium-sized, shorthaired dog distinguished by its short white coat with black or liver (brown) spots distributed uniformly over the entire body. The breed has a unique protein metabolism that results in high levels of uric acid excretion into the urine. As a result the breed is predisposed to urate uroliths and some dermatoses believed to be associated with this metabolic characteristic. It also is affected by inherited deafness and a cavitating leukodystrophy. Called also English coach dog, Carriage dog, Plum pudding dog, Fire house dog, and Spotted Dick.

  • normal uric acid (NUA) D’s. selective breeding of dogs without the gene mutation that causes high concentration of uric acid and predisposes to formation of uroliths, has produced a line of Dalmatians with a normal concentration of uric acid. Also called low uric acid (LUA) Dalmatians.

• Dalmatian insect powder see pyrethrum.

• Dalmeny disease see sarcocystosis.

• dalteparin [dal-tep′ -rin] a low-molecular-weight heparin used in dogs to treat hypercoagulability disorders and coagulation disorders such as pulmonary thromboembolism.

• dalton [dawl′t n] an arbitrary unit of mass, being one-twelfth the mass of the nuclide of carbon-12, equivalent to 1.657 × 10⁻²⁴ g. Called also atomic mass unit.

• Dalton’s law [dawl′t n] the pressure exerted by a mixture of nonreacting gases is equal to the sum of the partial pressures of the separate components. Called also Dalton’s Law of Partial Pressures.

• dam [dam] female parent.

  • d. line characteristics contributed to the offspring of a cross mating by the dam.
  • d.–offspring bond the close relationship of seeking, suckling and protecting imprinted at birth by sight, taste, and smell. Called also maternal bond.

• dam-family average the average performance of the full-sib family of which the subject is a member.

• Damalinia [dam″ -lin′e-] a genus of mammal lice of the superfamily Ischnocera. Also includes Bovicola and Werneckia. Damalinia (or Bovicola) bovis (cattle), D. (or Bovicola) caprae (goats), D. (or Bovicola) crassiceps (goats), D. (or Werneckia) equi syn. D. pilosus (horses), D. (or Bovicola) limbata (Angora goats), and D. (or Bovicola) ovis (sheep).

• DAMN IT acronym for a clinical investigation plan, based on probable pathophysiologic causes of the disease present. It consists of Degenerative, developmental; Allergic, autoimmune; Metabolic, mechanical; Nutritional, neoplastic; Inflammatory, immune-mediated, iatrogenic, ischemic, idiopathic; Toxic, traumatic.

• damping [damp′ing] 1. steady diminution of the amplitude of successive vibrations of a specific form of energy, as of electricity. 2. sprinkling a feed with water to reduce dust and inhalation of dust as a prevention of chronic obstructive respiratory disease in horses and dust tracheitis in feedlot steers.

• danazol [dan′ -zol] a gonadotropin inhibitor; suppresses luteinizng hormone (LH) and follicle-stimulating hormone (FSH) and estrogen synthesis. In animals, it has been used in the treatment of immune-mediated disorders, including hemolytic anemia and thrombocytopenia.

• dancing pigs see congenital tremor syndrome.

• dandelion [dan′d -li″ n] see Taraxacum officinale.

  • false d. see Hypochaeris radicata.

• dander [dan′d r] lay term for scales; dandruff.

• Dandie Dinmont terrier a small dog characterized by a long, low body, with pendulous ears, a curved ‘scimitar’ tail, and a medium length, crisp coat in colors described as mustard (fawn to reddish brown) or pepper (dark bluish black to light silvery gray). The legs are short, with the front being shorter than the rear so the shoulder height is about 10 in. The large head is accentuated by a fluffy topknot.

  D-02.

  

  Dandie Dinmont terrier.

• dandruff [dan′dr f] lay term for scaling.

  • walking d. cheyletiellosis; so-called because the light-colored mites are visible as they move across the hair coat.

• dandy-brush a grooming brush of stiff whisk fiber.

• Dandy–Walker syndrome [dan′de wawk′ r] congenital hydrocephalus due to obstruction of the foramina of Magendie and Luschka. A deformity in humans also recorded in dogs, foals, Holstein calves, and sheep. Called also Dandy–Walker malformation.

• danewort Sambucusebulus.

• dangerous wild animals animals that may be specified by local legislation as requiring a license if they are to be kept by a private person and outside circuses or zoos, which are legislated for separately.

• Danio rerio a tropical aquarium fish also used extensively as a biomedical research model. Called also zebrafish.

• Danish black pied cattle Danish black and white dairy cattle, originated from Dutch Friesian.

• Danish hobbles see Abildgaard method.

• Danish red cattle Danish red dairy cattle.

• Danish-Swedish farm dog a small, compact dog with a short, harsh, predominantly white, coat with patches of different colors. The tail is long or naturally short. Originally known as the Danish pinscher.

• Danish Swine Slaughter Data System a centralized, computer-based system by which pig health can be monitored via an abattoir meat inspection service. There is a standard list of diagnostic codes that ensures compatibility of results over a number of operators.

• DANMAP Danish Integrated Antimicrobial Resistance Monitoring and Research Programme. An integrated system involving animals, retail meat, and humans established by the Danish government to monitor antimicrobial resistance in food animals.

• danofloxacin antimicrobial agent of the fluoroquinolone group with a wide range of activity against bacteria and mycoplasmas.

• Danthonia widespread, perennial bunchgrass and a palatable pasture grass. Called also California oatgrass.

• danthron a by-product of the dye industry used as a purgative, especially in horses. Called also dihydroxyanthraquinone. Seldom used in modern practice.

• dantrolene [dan′tro-lēn] skeletal muscle relaxant producing its effect primarily on the neuromuscular junction and the muscle tissue, and only secondarily on the central nervous system. Used in the treatment or prevention of porcine malignant hyperthermia.

• Daphne [daf′ne] a genus of plants in the family Thymelaceae; contain dihydroxycoumarin glycosides, e.g., daphnetin; these are very toxic and cause severe irritation to the gut, leading to severe enteritis, vomiting, and diarrhea. Includes D. cneorum, D. genka, D. laureola, D. mezereum. Called also spurge laurel, February daphne, mezereon, garland flower, wood or copse laurel, wild pepper, spurge olive, dwarf bay.

• daphnetin [daf-ne′tin] toxic dihydroxycoumarin glycoside found in Daphne spp.

• Daphnia pulex [daf′ne- ] a water flea; one of the intermediate hosts of Echinuria uncinata, a roundworm of ducks.

• daphnin [daf′nin] a nontoxic glycoside in Daphne. Called alsomezerein.

• Daphniphyllum humile a plant in the family Daphniphyllaceae poisonous to cattle in Japan. Called also D. macropodum var. humile.

• dapple a spotted, mottled or irregularly pigmented coat color pattern, usually with darker colors on a lighter background, seen in some Dachshunds. A similar pigmentation pattern in longhaired dog breeds such as collies is usually called merle. Also occurs commonly in horses of any color, but is most striking in grays. May be noticeable only when the coat is short.

• dapsone [dap′sōn] an antibacterial that has been used to treat mycobacterial infections; has some anti-inflammatory effects. In dogs, it is also used to treat some immune-mediated skin diseases; contraindicated in cats. in all species, its use is limited by potentially severe side effects, including hepatitis and blood dyscrasias.

• darbepoetin alfa [dahr″be-poi′ -tin al′f] a synthetic form of erythropoietin used for the treatment of nonregenerative anemia associated with chronic kidney disease. It is also subject to abuse as a performanceenhancing drug in human athletes and in race horses.

• Darier disease an inherited disorder of cellular cohesion among keratinocytes, reported in English setters. Starting at a young age, affected dogs develop localized areas of alopecia, scaling, and crusting over pressure areas.

• dark [dark] approaching black; reflecting little light.

  • d. firm, dry muscle see dark cutting beef.
  • d. room a room dedicated to the processing of film; must be light-proof, temperature stable and fitted with water and power.

• Darling’s disease [dahr′ling] histoplasmosis.

• darmstadtium (Ds) a chemical element, atomic number 110, atomic weight 281.

• darnel [dahr′n l] see Lolium temulentum.

• Darrow’s solution a mixture of potassium chloride, sodium chloride and sodium lactate; used in fluid therapy to correct a potassium deficit. Called also lactated potassium saline injection. a mixture of potassium chloride, sodium chloride, and sodium lactate; used in fluid therapy to correct a potassium deficit. Also called lactated potassium saline.

• dart [dart] see blow dart.

  • d. gun see blow dart.

• Dartmoor pony English heavy pony, 12.2 hands high, bay, black or brown.

• dartoid [dahr′toid] resembling the dartos.

• dartos [dahr′tos] the contractile tissue under the skin of the scrotum; called also tunica dartos.

• darwinism [dahr′win-iz- m] the theory of evolution according to which higher organisms have been developed from lower ones through the influence of natural selection.

• dassie [das′e] see hyrax.

• Dasypsyllus gallinulae a species of flea in the order Siphonaptera. It is found on wild birds.

• Dasypus novemcinctus see armadillo.

• dasyurids marsupials in the family Dasyuridae, native to Australia and New Zealand. Includes phascogales, antechinus, quolls, dunnarts and kowari. Most are small, mouse-like, and primarily insectivorous. The large Tasmanian devil (Sarcophilus harrisii) is carnivorous.

• data [da′t ] plural of datum. A collection of information or facts. See also information.

  • d. adjustment for useful results data often need to be modified before analysis; for example, for age, for sex, for difficulty, or for number of attempts.
  • d. analysis submission of data to statistical analysis; includes sorting into categories and determining relationships between variables.
  • d. capture a mechanism for collecting specified segments or categories of data from a stream of automatically recorded data, some of which may be irrelevant for the specific purpose.
  • categorical d. are qualitative and suited to classification into categories. Further divisible into nominal (names), ordinal (levels of quality, development), dichotomized (mutually exclusive).
  • continuous d. data which have an infinite number of possible values.
  • diagnostic d. lists of diagnoses and data of clinical signs, clinical pathology results, and pathology lesions used in the making of diagnoses.
  • dimensional d. numerical or quantitative data. May be explicit and therefore continuous, or grouped into approximate groups, e.g., nearest whole number, i.e., discrete data.

    D-03.

    

    Dartmoor pony.

  • discrete d. data that have finite (usually whole integer) value and therefore fall naturally into groups of similar values; opposite to continuous data.
  • incidence d. data related to the occurrence of specific disease incidents.
  • minimum d. set an accepted list of terms and definitions necessary for veterinary records aimed at creating useful animal disease records. Called also uniform basic data set.
  • non-normal d. data whose frequency distribution is markedly different to that of normal data (see below).
  • normal d. data that manifest graphically as a bell-shaped curve distributed symmetrically about the peak value.
  • ordinal d. a type of data containing limited categories with a ranking from the lowest to the highest, e.g., very mild, moderate, severe.
  • paired d. see paired data.
  • passive d. data acquired from records collected for some other purpose.
  • pre-existing d. data in existence before the commencement of a study. Of limited value unless they are exactly the data required, have been collected adequately, and a group of pre-existing controls with their corresponding data can be identified.
  • prevalence d. disease occurrences are recorded against the size of the population at risk at the time.
  • raster d. representation one of two formats for data representation (the other being vector) in GIS consisting of a number of equally sized square cells (rectangles, hexagons, and equilateral triangles) forming a grid. The size of the grid determines the spatial resolution of the raster. Easy to manipulate but consumptive of computer storage. Called also grid data.
  • raw d. data as they are collected and before any calculation, ordering, etc., has been done.
  • screening d. data obtained by periodic diagnostic testing of randomly selected samples of a population.
  • secondary d. the use of data for purposes other than that for which it was intended.
  • sentinel d. data collected from sentinel animals or other recording units.
  • vector d. representation one of two formats for data representation (the other being raster) in GIS where points are represented as pairs of x, y coordinates, lines a string of points, and polygons as lines that form closed areas. Called also polygon data representation.

• data source the collecting agency.

• Datisca glomerata North American plant in the family Datiscaceae; contains an unidentified toxin that causes diarrhea, enteritis. Called also durango root.

• Datura [da-too′r ] a genus of toxic plants in the family Solanaceae; contain tropane alkaloids including hyoscine (scopolamine) and hyoscyamine (atropine) that cause excitement, restlessness, pupillary dilation, and dryness of the oral mucosa. Poisoning in animals is rare and usually results from eating crushed seeds. Includes D. candida (Brugmansia, angel’s trumpet), D. ferox (false castor oil plant, thorn apple), D. inoxia, D. leichhardtii, D. metel, D. meteloides, D. sanguinea (Brugmansia sanguinea), D. suaveolens (Brugmansia suaveolens), D. wrightii. D. stramonium is also reported to cause arthrogryposis in piglets when fed to their dams. Fortunately the plant is very unpalatable. Called also devil’s food, devil’s trumpet, false castor oil plant, Jamestown lily, Jamestown weed, jimson weed, mad apple, thorn apple.

• Daubentonia the plant genus Sesbania spp.

• daughter [daw′t r] 1. female offspring. 2. arising from cell division, as a daughter cell. 3. product of the decay or radioactive disintegration of a radionuclide. Usually formed as a result of successive transformations in a series. See also decay (3).

  • d. cyst see daughter cyst.

• daunomycin [daw-no-mi′sin] see daunorubicin.

• daunorubicin an anthracycline antibiotic produced by a strain of Streptomyces coeruleorubidus that is closely related to doxorubicin and has antimitotic, cytotoxic and immunosuppressive effects.

• Davainea [da-va′ne- ] a genus of tapeworms of the family Davaineidae.

  • D. proglottina causes severe enteritis in fowls and other gallinaceous birds.

• Davis forceps thumb-operated tissue forceps with a special atraumatic grasping surface to its blades—a hollow surrounded by shallow ridges. Designed for handling lung.

• Davison–Danielli membrane model first generally accepted model of membrane structure proposing a lipid bilayer as the basis of the structure.

• day blindness see hemeralopia.

• day length the number of daylight hours per day, increasing toward midsummer and the reverse toward midwinter. The effective trigger in the commencement and cessation of the breeding seasons in those species that demonstrate seasonal breeding.

• day-old chicks the standard output from the hatchery for broiler growers and egg producers in the poultry industry.

• days open the period between calving and conception in cows. Called also calving-to-conception interval.

• dazzle response eyelid closure and sometimes aversion of gaze in response to a bright light being directed into the eye; a test of all subcortical portions of light perception including the retina, optic nerve, and central visual pathways as far as the superior/rostral colliculus and the facial nerve.

• 2,4-DB 4-(2,4-dichlorophenoxy) butanoic acid; a phenoxyacid herbicide, not poisonous in its own right but may cause damaged plants to have higher than normal concentrations of nitrate.

• Db chemical symbol, dubnium.

• dB decibel.

• DCAD dietary cation-anion difference.

• DCT dry cow treatment.

• DD dichlorodiphenyldichloroethane, an insecticide; see chlorinated hydrocarbons.

• DDAVP see desmopressin.

• DDN dull, depress, nonresponsive; abbreviation used in medical records.

• DDT dichlorodiphenyltrichloroethane, see chlorinated hydrocarbons.

• DDVP see dichlorvos.

• DDx abbreviation for differential diagnosis; used in medical records.

• de- word element. [L.] down from; reduce, reverse, away from.

• de Bruin spatula a small, hand-held obstetrical spatula manipulated from inside the uterus and used to remove the skin of the fetus by blunt dissection.

• De Qi sensation felt when an acupuncture point is stimulated. This sensation may feel like distention or throbbing or an electrical impulse in the area of the acupuncture point.

• de Vita pin a bone pin used to stabilize hip luxations by being placed ventral to the ischial tuberosity, dorsal to the femoral neck, and into the ilium. It forms an extension of the dorsal and lateral acetabular rim. Called also ischioilial pin.

• DEA dog erythrocyte antigen.

• dead [ded] destitute of life; the state of death.

• dead animal disposal in most intensive farming areas, dead stock facilities (knackery yards in some countries) and rendering works are markets for cadavers. In extensive farming areas, burning or burial is desirable, but natural decay is a common outcome. Composting is increasingly used.

  • dead space the volume of air that is inhaled that does not take part in the gas exchange, either because it is in the conducting airways or it ventilates alveoli that are not perfused or are poorly perfused.

• deadgrass [ded′gras] a coat color of pale yellow to tan, used particularly to describe Chesapeake Bay retriever dogs.

• deaf [def] lacking the sense of hearing or not having the full power of hearing; exhibiting deafness.

• deafness [def′nis] lack or loss, complete or partial, of the sense of hearing.

  • conductive d. deafness in which sound vibrations are interrupted in the outer or middle ear and do not reach the inner ear and its nerve endings. Most commonly caused by otitis externa and the presence of debris in the external ear canal or tympanic bulla.
  • congenital d. infrequent in dogs and cats, except in certain breeds; not recorded in other species. In most cases is due to cochlear duct degeneration. See also inherited deafness (below).
  • cortical d. that due to disease of the cortical centers of the cerebrum.
  • inherited d. occurs in some blue-eyed white cats and in some dog breeds; particularly common in the Dalmatian. In some, it is associated with coat coloration, e.g., white Bull terriers, merle collies, and Old English sheepdogs.
  • nerve d. due to degeneration of the acoustic sensory organ. Most common in dogs at an early age and associated with incomplete pigmentation of the haircoat and the uvea, in animals with a white or merle coat color. Occurs also in mink, cats, and mice.
  • senile d. due probably to degeneration of the hair cells in the organ of Corti, and to loss of neurons in the spinal ganglion; very common in aged dogs. Called also presbycusis.
  • sensorineural d. due to damage of the inner ear nerve endings, the cochlear portion of the eighth cranial nerve, the vestibulocochlear nerve, or the cortical hearing center. See also nerve deafness (above).
  • toxic d. overdosing with aminoglycoside antibiotics causes deafness.
  • transmission d. conductive hearing loss.

• deamidase [de-am′ľ-dās] an enzyme that splits amides to form a carboxylic acid and ammonia.

• deamidization [de-am″ľ-dľ-za′sh n] liberation of the ammonia from an amide.

• deaminase [de-am′ľ-nās] an enzyme causing deamination, or removal of an amino group from organic compounds, named according to its substrate as adenosine deaminase, cytidine deaminase, guanine deaminase, etc.

• deamination [de-am″ľ-na′sh n] removal of the amino group, −NH₂, from a compound.

• deAngelis technique a method for extra-articular reconstruction of the cranial cruciate ligament that involves placement of an imbrication suture from the lateral femero-fabella ligament to the distal patellar tendon.

• death [deth] the cessation of all physical and chemical processes that invariably occurs in all living organisms. Even in humans there is at present no standardized diagnosis of clinical death. The existing procedure, and the one recommended for use in animals, is to declare the animal dead when brain death has occurred. Brain death has occurred when the animal is in a deep irreversible coma. The criteria on which a diagnosis of brain death can be made are: (1) absolute unresponsiveness to externally applied stimuli; (2) cessation of movement and breathing, including no spontaneous breathing for 3 minutes after an artificial respirator has been turned off; and (3) complete absence of cephalic reflexes. The pupils of the eyes must be dilated and unresponsive to direct light.

  • d. agony involuntary movements of all parts of the body in the few moments before death.
  • d. camas see Zigadenus.
  • d. cap a mushroom, Amanita phalloides.
  • clinical d. the absence of heartbeat and cessation of breathing.
  • d. rate the number of deaths per stated number of animals in a specified region in a specified, usually annual, time period.

• DeBakey [de-ba′ke] pertaining to Michael E. DeBakey (1908–2008), American cardiovascular surgeon.

  • D. bulldog clamps surgical instruments designed for temporary occlusion of large blood vessels.
  • D. tissue forceps delicate surgical thumb forceps with longitudinal ribs, designed for delicate, nontraumatic surgery.

• debarking see devocalization.

• debeaking removal of part of the beak, usually the front third of the upper beak, of domestic fowls to prevent feather picking and other cannibalistic vices in caged birds. Achieved using a hot knife or by infrared beak treatment (IRBT) technology. Called also beak trimming. See also cannibalism.

• debilitation being in a state of debility.

• debility [d -bil′ľ-te] lack or loss of strength; weakness.

• debleating resection of the vocal cords in a pet goat or sheep that has become a noise nuisance in an urban environment.

• deboned carcass meat from which the bone has been removed.

• debrancher enzyme [de-branch′ r en′zīm] an enzyme involved in the glycogenolytic process of releasing glucose from glycogen. A deficiency of the enzyme results in accumulation of glycogen in tissues. Both are characteristics of type III glycogen storage diseases.

• débride [da-brēd′] [Fr.] to remove by débridement.

• débridement [da-brēd-maw′] [Fr.] the removal of all foreign material and all contaminated and devitalized tissues from or adjacent to a traumatic or infected lesion until surrounding healthy tissue is exposed.

  • bandage d. the use of bandages and dressings, such as wet-to-dry or wetto-wet dressings to debride a contaminated wound by frequent changes of dressing.
  • block d. a method in which the wound is packed with gauze or toweling, sutured together and then the entire mass is removed surgically. Usually reserved for badly damaged tissues.
  • enzymatic d. use of enzymes such as trypsin and chymotrypsin, usually applied topically, to achieve débridement.
  • surgical d. the use of surgery to remove all contaminated and devitalized tissues from a wound. Can be performed as a single procedure or staged over several procedures in severe wounds.

• debris [d -bre′] devitalized tissue or foreign matter.

• debulking [de-bulk′ing] removal of excess bulk of tissue from a lesion, usually a tumor, either to assist in healing or as an adjunct to chemotherapy.

• DEC diethylcarbamazine.

• deca- (da) [Gr.] ten a prefix used in naming units in the metric and SI systems of measurement to indicate a quantity 10 times the unit.

• decalcification [de-kal″sľ-fľ-ka′sh n] 1. the process of removing calcareous matter. Used in processing of bone samples for histological sections. 2. the loss of calcium salts from bone or teeth.

• decalcify [de-kal′sľ-fi] to deprive of calcium or its salts.

• decannulation [de-kan″u-la′sh n] the removal of a cannula.

• decanoate [dek″ -no′āt] a salt of decanoic acid.

• decanoic acid [dek″ -no′ik] one of the saturated fatty acids found in the endosperm of the coconut (Cocos nucifera), in coconut oil and in other seed oils. Used in diets for patients with fat malabsorption syndromes. Called also n-capric acid.

• decantation [de″kan-ta′sh n] the pouring of a clear supernatant liquid from a sediment.

• decapeptide [dek″ -pep′tīd] a polypeptide consisting of a chain of ten amino acids.

• decapitation [de-kap″ľ-ta′sh n] removal of the head, as of an animal, fetus or bone.

• decapsulation [de-kap″su-la′sh n] removal of a capsule, especially the renal capsule. See also capsulectomy.

• decarboxylase [de″kahr-bok′s -lās] any of the lyase class of enzymes that catalyze the removal of a carboxyl group from a compound and releases carbon dioxide.

  • d. test tests for the identification of bacteria, based on the production of ammonia from lysine, ornithine or arginine. In a positive result, the alkaline product is indicated by bromocresol purple.

• decarboxylation [de″kahr-bok″s -la′sh n] removal of the carboxyl group from a compound.

• decay [de-ka′] 1. the gradual decomposition of dead organic matter. 2. the process or stage of decline, as in old age. 3. in radioactivity terminology the disintegration of the nucleus of an inactive nuclide by the spontaneous emission of alpha or beta particles. Called also radioactive disintegration. Substances produced by the disintegrations are called daughter (3) compounds.

  • d.-accelerating factor a membrane-associated protein found on many cells, including peripheral blood cells, that prevents assembly or speeds disassembly of C3 convertase (C3bBb), down-regulating the activity of complement.

• decerebellate an animal from which the cerebellum has been removed, experimentally or, less commonly, accidentally.

  • d. rigidity posture that results from severe lesions of the cerebellum, especially the rostral portion of the cerebellum or peduncles and which result in functional disconnection of the cerebellum from the brainstem. The forelimbs are held in rigid extension while the hindlimbs are flexed cranially at the hip. The posture may also include a degree of opisthotonus.

• decerebrate [de-ser′ -brāt] 1. to eliminate cerebral function by physically or functionally disconnecting the cerebral hemispheres from the brainstem at the level of the cerebral peduncles or by ligating the common carotid arteries and basilar artery at the center of the pons 2. an animal so prepared, or a brain-damaged animal with similar neurological signs.

• decerebration [de-ser″ -bra′sh n] the act of decerebrating.

• decholesterolization [de″k -les″tr-ol-ľ-za′sh n] reduction of cholesterol concentrations in the blood.

• deci- (d) [L.] one-tenth; a prefix used in the metric system to indicate one-tenth (10⁻¹) of the unit.

• decibel (dB) [des′ľ-b l] a unit used to express the relative intensity and pressure of sound; the ratio of two powers, usually electric or acoustic powers, equal to one-tenth of a bel; one decibel equals approximately the smallest difference in acoustic power the human ear can detect.

• decidua [d -sid′u-] a name applied to the human and primate endometrium during pregnancy, all of which except, for the deepest layer, is shed after birth of the young. Called also the decidual, or deciduous, membrane.

  • basal d., decidua basalis that portion on which the implanted ovum rests.
  • capsular d., decidua capsularis that portion directly overlying the implanted ovum and facing the uterine cavity.
  • parietal d. the decidua exclusive of the area occupied by the implanted ovum. Called also true decidua, decidua verra.
  • true d. see parietal decidua (above).
  • d. verra see parietal decidua (above).

• deciduate, deciduous, decidual [d -sid′u-āt, d-sid′u-s, d-sid′u- l] characterized by shedding, e.g., teeth, placenta.

  • d. placenta, deciduate membrane endothelial and hemochorial placenta.

• deciduation [d -sid″u-a′sh n] the shedding of the decidua.

• deciduitis [d -sid″u-i′tis] a bacterial disease leading to changes in the decidua.

• deciduoma [d -sid″u-o′m] an intrauterine mass containing decidual cells.

• deciduosis [d -sid″u-o′sis] the presence of decidual tissue or of tissue resembling the endometrium of human or primate pregnancy in an ectopic site.

• deciduous [d -sid′u- s] falling off; subject to being shed, as deciduous teeth.

• decile [des′īl] one of the groups when a series of ranked data is divided into ten equal parts, or dividing points between such groups. See also quartile.

• decimal scale in homeopathy, the scale of dilution of a remedy. Each dilution is one in ten.

• decision a choice between a number of possible answers to a question.

  • d. analysis a systematic approach to decision making under conditions of imperfect knowledge; a practical application of probability theory. Used to calculate the optimal strategy from among a series of alternative strategies. Can be expressed graphically in the form of a decision tree (below).
  • d. making making a decision can be done in three principal ways and many variations and mixtures of the methods: (1) rote, the decision is made on the basis of a set of rules and no selectivity is required; (2) intuitive, decisions are made on the basis of cerebrally stored information and reasoning systems which permit a fast response; (3) decision analysis, a means of solving complicated problems by including all of the factors that could possibly affect the outcome of the analysis in a series of sequential questions. This gives each of the factors an opportunity of affecting the outcome. The chance of error by omission can be eliminated but the process is prolonged.
  • d. theory the theoretical basis for decision analysis.
  • d. tree a diagrammatic representation of the possible outcomes and events used in decision analysis. The questions to be asked in an analysis of a question are arranged as a series of nodes each with a yes and no branch, creating an arborization effect. The sequential steps proceed with each step depending on the decision made in the preceding step.

• decking multiple decks in animal accommodation or transportation facilities. Common for young animals, chiefly piglets, commercial poultry, laboratory animals, cats, and dogs.

• declawing [de-klaw′ing] surgical removal of the claws of Felidae and Canidae. Not a universally accepted procedure except where there are specific health implications for the patient. Can happen accidentally in penned wildlife, e.g., anteaters. Called also onychectomy.

• declive [de-kli′ve] a slope or a slanting surface. The part of the vermis of the cerebellum just caudal to the primary fissure.

• declivis [de-kli′vis] [L.] declive.

• decoction [de-kok′sh n] steeping of a substance, usually woody stems, barks, berries, rhizomes and root material, in water to obtain its soluble principles and use as a tea for oral administration. See also infusion (1).

• decoloration [de-kul″ r-a′sh n] 1. removal of color; bleaching. 2. lack or loss of color.

• decombing surgical removal of the comb in the chicken or young bird where there is a likelihood of damage to the comb or to facilitate protrusion of the head through the bars of a battery cage. Pendulous wattles may be treated in the same way. Called also dubbing.

• decompensation [de-kom″p n-sa′sh n] failure of compensation.

• cardiac d. inability of the heart to maintain adequate circulation; it is marked by one or more combinations of dyspnea, venous engorgement, cyanosis, and edema.

• decomposition [de″kom-p -zish′ n] 1. biologically speaking, the separation of compound bodies into their constituent principles; the natural process of biodegradation of animal and plant materials. Its occurrence in human and animal foods is a constant threat and preventing it is the prime objective of the food hygienist. 2. statistically speaking, the removal of accountable influences on a set of data so that only variation due to random error remains.

• decompression [de″kom-presh′ n] 1. the return to normal environmental pressure after exposure to greatly increased pressure, as in the removal of an outside substance that is compressing an organ, structure, or tissue. i.e., spinal decompression via hemilaminectomy. 2. the artificial lowering of barometric pressure, e.g., to simulate high altitude.

  • cerebral d. removal of a flap of the skull and incision of the dura mater for the purpose of relieving intracranial pressure. Decompression can also be accomplished by the intravenous injection of hypertonic solutions, e.g., mannitol, usually accompanied by parenteral corticosteroids.
  • gastric d. by stomach tube or transperitoneal needle tap (trocharization). An essential part of treatment for acute gastric dilatation in dogs and horses.

• deconditioning, detraining [de″k n-dish′ n-ing] reversal of the traininginduced adaptations, usually for physical activity; loss of fitness.

• decongestant [de″k n-jes′t nt)] 1. tending to reduce congestion or swelling. 2. an agent that reduces congestion or swelling, usually of the nasal membranes. Decongestants may be inhaled, administered as spray or nose drops, or used orally in liquid or tablet form. The medication acts by reducing mucosal swelling and thus opening up the airway. Among the leading medications used as decongestants are epinephrine (adrenaline), ephedrine, and phenylephrine. Antihistamines, alone or in combination with decongestants, may also be effective.

• decongestive [de″k n-jes′tiv] reducing congestion.

• decontamination [de″k n-tam″ľ-na′sh n] a step in treatment for toxicosis; includes washing from the body surface, inducing emesis, and administration of activated charcoal and sometimes a cathartic.

• decoppering agents drugs which promote excretion of copper; includes d-penicillamine, trientine (2,2,2-tetramine) and 2,3,2-tetramine.drugs which promote excretion of copper; include d-penicillamine, trientine (2,2,2-tetramine), and 2,3,2-tetramine.

• decoquinate [de-ko-kwin′āt] a quinolone anticoccidial that is nontoxic but subject to a high rate of development of resistant coccidia.

• decorin [dek′ -rin] a small chondroitin sulfate proteoglycan found in connective tissue and bone, thought to be involved in the organization and mineralization of bone.

• decortication [de-kor″tľ-ka′sh n] 1. removal of the outer covering from a plant, seed or root. 2. removal of portions of the cortical substance of a structure or organ, as of the visceral pleura in surgical treatment of fibrosing pleuritis.

• decrement [dek′r -m nt] the recovery after a fever; the excessive stored heat is dissipated by vasodilatation and sweating, and heat production is reduced by relaxation of muscles. Called also defervescence.

• decremental conduction a phenomenon that occurs in the cardiac AV node when, during complete AV block, continued stimulation causes a slowing and diminished amplitude of phase 0 in the AV nodal cells until a nonpropagated local response occurs.

• decrudescence [de″kroo-des′ ns] diminution or abatement of the intensity of clinical signs.

• Decrusia a genus of nematodes of the family Strongylidae. Includes D. additicta (found in the large intestine of Indian elephants).

• decubital ulcer [de-ku′bľ-t l] an ulcer of the skin and underlying tissues and due to local interference with the circulation; called also pressure sore. The ulcer usually occurs over a bony prominence such as that of the sacrum, hip, heel, shoulder, or elbow. Excessive or prolonged pressure produced by the weight of the body or limb is the primary cause.

• decubitus [de-ku′bľ-t s] pl. decubitus. 1. the act of lying down; the position assumed in lying down. 2. a decubitus ulcer.

  • dorsal d. lying on the back.
  • lateral d. lying on one side, designated right lateral decubitus when the subject lies on the right side and left lateral decubitus when it lies on the left side; lateral recumbency.
  • d. ulcer see decubital ulcer.
  • ventral d. lying on the stomach.

• decussate [de-kus′āt] see decussation.

• decussatio nervorum trochlearium [de″k -sa′she-o] the decussation of the trochlear nerve.

• decussation [de″k -sa′sh n] a crossing over; the intercrossing of fellow parts or structures especially in the form of an X.

  • d. of pyramids the ventral part of the caudal medulla oblongata in which some of the fibers of each pyramid intersect as they cross the midline and descend as the lateral corticospinal tracts.

• dedifferentiation [de-dif″ r-en″she-a′sh n] regression from a more specialized or complex form to a simpler state.

• dedrobenzperidol see droperidol.

• DEDSV duck egg drop syndrome virus.

• dee [de] a metal part shaped like a capital D and used in harness to make a T junction.

• deep litter [dēp] a husbandry system for the layering of indoor bedding, especially poultry. Any form of bedding is used, but short material such as shavings or sawdust is most easily handled. After an initial shallow layer is fouled, more litter is added to cover the feces. Additions are continued daily until the end of the housing period when the entire bed is removed. Properly cared for the system is clean and warm and easy on labor.

• deer [dēr] ruminants in the Cervidae family; see also elk, reindeer, wapiti, moose and muntjac.

  • black-tailed d. (Odocoileus hemionus columbianus) a native of the Pacific Northwest of the US; subspecies of mule deer (below).
  • barking d. see muntjac.
  • chital d. (Axis axis) medium sized deer native to India, light brown to golden colored, dorsal body covered in white spots, with white abdomen and throat. Antlers, present only on males are three-pronged and large. Chital were introduced to several Hawaiian islands for hunting, where they are abundant; low numbers present in other countries, including Australia.
  • fallow d. (Dama dama) a small, 150-lb, fawn deer with white spots and a white spot bordered with black on each buttock, native throughout Europe and the Middle East, but introduced in many other locations, particularly game parks. The males have broad, multi-point antlers.
  • d. fly fever see tularemia.
  • d. herpesvirus malignant catarrhal fever in deer is associated with malignant catarrhal fever virus–white-tailed deer (MCFV-WTD). Goats are probable carriers.
  • hog d. (Hyelaphus porcinus) a small, short-legged deer native to South and Southeast Asia, but introduced in other countries. It is distinguished by its preference to run, rather than leap, with head held low. Males have three-tined antlers.
  • d. mouse see deer mouse.
  • mouse d. see mouse deer.
  • mule d. (Odocoileus hemionus) small, 3-ft deer, native to the western US; has large, mule-like ears and tail tipped with black.
  • red d. (Cervus elaphus) the principal hunting deer; golden red-brown, large, 5 ft tall, and up to 650 lb; males have very large antlers. Widespread through Europe, parts of Asia and is the only deer that inhabits Africa.
  • roe d. (Capreolus capreolus; western roe deer) a small deer, native to Europe and the Middle East; it is a game animal. They are red-gold to black with white buttock patch; males are called roebuck and have three-tined antlers. Also known as European roe deer.
  • sambar d. see sambar.
  • sika d. (Cervus nippon) a small- to medium-sized, forest-welling deer native to Japan and East Asia, but it has been introduced to a number of other countries. It has a reddish-brown coat with rows of white spots on the back, a large white rump, and a neck mane. Males have short, straight antlers with two to five tines, which are used in Chinese traditional medicine. Some subspecies are endangered. Also know as spotted deer or Japanese deer.
  • d. tick fever 1. Lyme disease. 2. tularemia.
  • white-tailed d. (Odocoileus virginianus) a medium-sized, graceful red to gray deer native to North, Central and South America and introduced to New Zealand, Europe, and other countries.

• Deerhound in the US, a common name for Scottish deerhound; the name recognized for the breed in the UK.

• DEET [dēt] diethyltoluamide.

• defatted [de-fat′ d] 1. fat is removed from the tissue by fat solvents. 2. deprived of fat as a food.

• defaunate [de-fawn′āt] elimination of microscopic fauna, especially protozoa, in the rumen and cecum, with depressing effects on digestion.

• defeathering plucking of feathers from bird carcasses after immersion momentarily in 135–145°F water. Final treatment of poultry is singeing. Ducks are waxed.

• defecate [def′ -kat] the act of defecation.

• defecation [def″ -ka′sh n] elimination of wastes and undigested food, as feces, from the rectum.

  • painful d. see dyschezia.

• defect [de′fekt] an imperfection, failure or absence.

  • filling d. an interruption in the contour of the inner surface of viscus revealed by contrast radiography, indicating excess tissue or substance on or in the wall of the organ, foreign body, or other space-occupying lesions.
  • negative d. in neurology, a movement that cannot be performed, such as in paresis or paralysis.

    D-04.

    

    Mule deer (Odocoileus hemionus) the major host of the adult winter ticks, Dermacentor albipictus. Courtesy of CDC.

  • positive d. in neurology, an involuntary movement, such as tremors, abnormal posture, or seizures.
  • septal d. a defect in the cardiac septum resulting in an abnormal communication between opposite chambers of the heart. See also aortic septal defect, atrial septal defect and ventricular septal defect.

• defective interfering virus [de-fek′tiv] viral particles containing subgenomic amounts of nucleic acid usually produced following infection of cells at high multiplicity and that interfere with the replication of complete virions.

• defective virus [de-fek′tiv] one unable to replicate on its own and needing to be complemented by a ‘helper’ virus for replication.

• defeminization [de-fem″ľ-nľ-za′sh n] loss of female sexual characteristics.

• defense [de-fens′] 1. against infection, including hematological and immunological systems. 2. behavior directed to protection of the individual from injury.

  • d. mechanisms means by which the host repels invading organisms; externally, these include the barrier provided by the skin and epithelial lining of the gastrointestinal, genitourinary, and respiratory tracts, together with their secretions and normal microflora, and internally, phagocytic cells, humoral, and cellular immunity.
  • d. reaction the physiological reaction to emotional stress, particularly fear, includes tachycardia, increased cardiac output, vasodilation in skeletal muscle, elevation of blood pressure. Behavioral responses include alerting and aggressive behavior.

• deferens [def′ r-enz] [L.] deferent.

• deferent [def′ r- nt] conducting or progressing away, as from a center or specific site of reference.

  • d. duct see ductus deferens. Called also vas deferens.

• deferentectomy [def″ r-n-tek′t -me] excision of a ductus deferens. See also vasectomy.

• deferential [def″ r-en′sh l] pertaining to the ductus deferens.

• deferentitis [def″ r- n-ti′tis] inflammation of the ductus deferens.

• deferoxamine [d -fr-oks′ -mēn] an iron-chelating compound used to treat iron poisoning. Called also desferrioxamine.

• deferral days an important item in dairy cow fertility data; management needs may dictate that cows are not to be bred at their first or subsequent estrus; such delays should not be counted into the average calving-to-mating interval.

• defervescence [def″ r-ves′ ns] the period of abatement of fever. Called also decrement.

• defibrillation [de-fib″rľ-la′sh n] 1. termination of atrial or ventricular fibrillation, usually by electric shock. 2. separation of tissue fibers by blunt dissection. Defibrillation by precordial shock is accomplished by delivering a nonsynchronized direct current to the myocardium. It is an emergency procedure, used to terminate a life-threatening ventricular arrhythmia. The electric shock is delivered by means of metal paddles applied directly to the heart muscle, as in cardiac surgery, or by placing the paddles on the chest (closed defibrillation). The high-voltage electrical current delivered during precordial shock causes complete depolarization of the heart muscle, disrupting all of the electrical circuits that are activating the heart muscle and causing ventricular fibrillation. This allows the heart’s natural pacemaker to regain control and regulation of the heart rate and rhythm.

  • chemical d. where electrical equipment is not available for defibrillation, some combinations of drugs have been used. These include potassium chloride followed by calcium chloride or potassium chloride and acetylcholine.

• defibrillator [de-fib″rľ-la′t r] an apparatus used to produce defibrillation by application of brief electroshock to the heart, directly or through electrodes placed on the chest wall.

  • chemical d. certain antiarrhythmic drugs are effective as antifibrillation agents and can be used in emergency situations to convert ventricular fibrillation to a sinus rhythm.

• defibrination [de-fi″brľ-na′sh n] the destruction or removal of fibrin, as from the blood.

  • d. syndrome see disseminated intravascular coagulation.

• deficient a state of being in deficit.

• deficit [def′ľ-sit] a lack or deficiency.

  • oxygen d. a lack of oxygen, as in hypoxia or anoxia.

• defining criterion the hallmark of each disease; a characteristic lesion or result of a clinicopathological test or clinical sign without which the diagnosis cannot be made. Called also key sign.

• definition [def″ľ-nish′ n] establishment of a clear boundary, a clear line of demarcation.

  D-05.

  

  Defibrillator.

  • clinical d. an accurate description of the disease in terms of clinical signs and clinicopathological findings.
  • epidemiological d. an accurate description of the disease in terms of its epidemiological parameters of when, where, why and how it has occurred.
  • genetic d. an accurate description of a disease in terms of the familial relationships between affected animals.
  • radiographic d. a sharp line of demarcation between structures of different radiographic opacities.

• deflation receptor [de-fla′sh n] receptors in the upper airways that are part of the Hering–Breuer reflexes.

• defleecing [de-flēs′ing] see shearing.

• deflighting [de-flīt′ing] removing the ability of a bird to fly; can be effected by clipping of the flight feathers on one or both wings, temporarily by bandaging one wing in a flexed position, or permanently by pinioning or patagiectomy.

• defluorination reduction of the fluorine content of a feed to below the level accepted as being nontoxic.

• defluvium [de-floo′ve- m] [L.] a falling out, as of the hair.

• defluxion [de-fluk′sh n] a falling out, as of hair; defluvium. See also anagen defluxion, telogen defluxion.

• defoliant a chemical used to remove the leaves from plants to facilitate mechanical harvesting. The early defoliants, especially arsenical compounds, presented serious hazards if the plants were later fed to livestock or if the spray drifted to nearby pasture paddocks. Modern defoliants are nontoxic if used according to manufacturer’s recommendations. See MCPA, tributyl triphosphorotrithioite, thidiazuron.

• deformability [de-form″ -bil′ľ-te] the ability of cells, such as erythrocytes, to change shape as they pass through narrow spaces, such as the microvasculature.

• deformation [de″for-ma′sh n] 1. deformity, especially an alteration in shape or structure. 2. the process of adapting in shape or form.

• deforming cervical spondylosis [de-form′ing] see hypervitaminosis A.

• deformity [d -for′mľ-te] distortion of any part or general disfigurement of the body; malformation.

  • angular limb d’s. deviation of the limb from the vertical alignment by angulation at the joints or in the bones themselves. May be congenital or acquired; includes genu varus (bowleg) and genu valgus (knock-knee).

• deformylase a prokaryotic enzyme that removes the formyl group from amino acids, e.g., the methionine coded by the initiation codon AUG.

• DEFRA Department for Environment, Food and Rural Affairs (UK). Replaces what was once the Ministry of Agriculture, Fisheries and Food (MAFF).

• degenerate [de-jen′er-āt] 1. to change from a higher to a lower form. 2. characterized by degeneration.

• degeneration [de-jen″ r-a′sh n] deterioration; change from a higher to a lower form, especially change of tissue to a lower or less functionally active form. When there is chemical change of the tissue itself, it is true degeneration; when the change consists in the deposit of abnormal matter in the tissues, it is infiltration. See also Wallerian degeneration, Zenker’s necrosis.

  D-06.

  

  Carpal deformity in a calf.

  • albuminoid d. cloudy swelling, an early stage of degenerative change characterized by swollen, parboiled-appearing tissues that revert to normal when the cause is removed.
  • ballooning d. swelling of the cytoplasm in epidermal cells without vacuolization, enlarged or condensed nuclei, and acantholysis. A characteristic of viral infections of the skin. Called also koilocytosis.
  • caseous d. caseation (2).
  • colloid d. degeneration with conversion of the tissues into a gelatinous or gum-like material.
  • cystic d. degeneration with formation of cysts.
  • fatty d. see fatty change.
  • feathery d. said of hepatocytes; a hydropic change in hepatocytes that have suffered long-term exposure to cholestasis.
  • fibrinoid d. deposition or replacement with eosinophilic fibrillar or granular substance resembling fibrin.
  • fibroid d. degeneration into fibrous tissue.
  • hyaline d. a regressive change in cells in which the cytoplasm takes on a homogeneous, glassy appearance; also used loosely to describe the histological appearance of tissues. Called also hyalinosis.
  • hydropic d. see hydropic degeneration.
  • macular d. degenerative changes in the macula retinae; seen in primates only.
  • mucoid d. degeneration with increased mucin that can be epithelial or mesenchymal in origin.
  • mucous d. degeneration with accumulation of mucus in epithelial tissues. Called also myxomatous degeneration.
  • myxomatous d. see mucous degeneration (above).
  • reticular d. extreme intracellular edema of epidermal cells, resulting in rupture and multilocular intraepidermal vesicles with septae formed by the remaining cell walls. Seen in acute inflammatory dermatoses.
  • retinal d. degeneration of the retina with concomitant reduction in vision (typically night vision and then day vision); most commonly inherited, but can also be due to previous detachment, glaucoma, nutritional causes, toxicity, chorioretinitis, or sudden acquired retinal degeneration (below).
  • spongy d. on microscopic examination has the physical appearance of a sponge. Usually applied to tissue of the central nervous system, caused by the loss of myelin.
  • sudden acquired retinal d. (SARD, SARDS) a form of retinal degeneration seen only in dogs (typically middle aged female dogs) in which there is sudden onset of complete blindness. Often associated with Cushingoid-like signs. There are no funduscopically visible changes for 4–8 weeks following vision loss. Diagnosed using electroretinography.

• degenerative [de-jen′ r- -tiv] pertaining to or emanating from degeneration. See also arthropathy, axonopathy, encephalomalacia, degenerative joint disease, myeloencephalopathy, myopathy, osteoarthritis.

  • avian d. joint disease common in coxofemoral joints of mature male turkeys and meat chickens.
  • d. disease a disease in which the sole pathogenesis is degeneration; that is without the intervention of other pathogeneses, e.g., inflammation, traumatic injury, neoplasia.
  • d. joint disease see osteoarthritis.
  • d. myopathy due to pressure ischemia in well-conditioned cattle that are recumbent for 24 hours or more; affected muscles are pale, the serum creatine phosphokinase and glutamic-oxaloacetic transaminase concentrations are markedly elevated for brief periods; commonly the condition is irreversible.

  D-07.

  

  A normal gerbil tail and a degloved gerbil tail caused by improper restraint of the gerbil. Quesenberry, K., Carpenter, J. Ferrets, Rabbits, and Rodents, 3rd Edition. W.B. Saunders Company, 2011.

• degloving [de-gluv′ing] the avulsion of skin of extremities from underlying structures, usually a result of trauma, with a pattern mimicking removal of a glove.

• deglutition [deg″loo-tish′ n] the act of swallowing. There are differences in the mechanism between birds and mammals. Most birds cannot swallow without raising their heads.

• degradation [deg″r -da′sh n] conversion of a chemical compound to one less complex, as by splitting off one or more groups of atoms.

• degranulation [de-gran″u-la′sh n] the loss of granules; usually refers to the secretory granules in certain cells, e.g., pituitary chromophobes, acidophils, and basophils. In basophils and mast cells, it is associated with the release of active substances from the cells and is characteristic of type I immediate hypersensitivity.

• degreasing agent one used to remove excessive sebaceous secretions and scale from the skin; examples include shampoos containing selenium sulfide or benzoyl peroxide.

• degree [d -gre′] 1. a grade or rank awarded scholars by a college or university. 2. a unit of measure of temperature. 3. a unit of measure of arcs and angles, one degree being 1/360 of a circle.

• degrees of freedom used to define statistical distributions of several tests, usually based on the number of data items less the number of parameters estimated.

• degu (Octodon degus) a small South American rodent, native to Chile; used as a laboratory animal in neuroscience research and the study of diabetes. Also popular as a pet.

• degustation [de″g s-ta′sh n] the act or function of tasting.

• DEHA dehydroepiandrosterone

• dehairing [de″hār′ing] removal of hairs and bristles of slaughtered pigs by a scraper after scalding in a tank or a steam cabinet.

• dehiscence [de-his′ ns] a splitting open, as in a surgical wound.

• dehorner [de-hor′n r] instrument for removing the horns.

  • Barnes d. two sharp-edged scoops hinged together. Opening them forcefully brings the cutting edges together. Suitable for calves up to 3–4 months of age.
  • hot cautery d. an electrically heated instrument that resembles a round soldering iron with a flat, indented head. The iron is heated to red heat and placed over the horn to burn a ring of skin at the base of the horn. The horn is not removed but is allowed to slough. Satisfactory for use in calves up to 2 months of age.
  • Keystone d. a guillotine type instrument with detachable blades. Has handles 3 ft long and is capable of chopping off the largest cow horns and most bull horns.
  • tube d. a metal tube with a very sharp edge at one end and a wooden round palm-fitting handle at the other. The tube is placed over the horn and rotated to isolate the horn skin. The tube edge is then used as a gouge to remove the horn. A hole in the side of the tube permits the debris to be removed. For use in calves up to 2–3 months of age.

• dehorning [de-hor′ning] the removal of horns either by caustic paste or electrocautery when very young or by surgical amputation with a dehorner or saw at any age. Special care is needed with goats because of their extreme reaction (shock) if induced pain is not addressed.

  • d. nerve block see cornual block.

  D-08.

  

  Use of a Barnes dehorner or scoop for removal of the horns in a calf.

• dehull to remove the outer covering of a seed used as feed. Improves the nutrient value of the grain. The hulls may be used separately as a roughage supplement.

• dehumidifier [de″hu-mid′ľ-fi″ r] an apparatus for reducing the content of moisture in the atmosphere.

• dehydratase [de-hi′dr -tās] any enzyme of the lyase class that catalyzes the removal of H₂O, leaving double bonds (or adding groups to double bonds).

• dehydrate [de-hi′drāt] 1. to undergo the process of dehydration. 2. reduce the moisture content of a feed by drying.

• dehydrating agent agent used in the clearing and mounting of tissue slides for microscopic examination, e.g., ethanol, butanol, isopropanol.

• dehydration [de″hi-dra′sh n] the state when the body loses more water than it takes in. There is a negative fluid balance with the result that total body water volume is less than normal, with reductions in intracellular and extracellular fluid volumes.

  • cellular d. caused by increased osmoconcentration of the extracellular fluid.

• dehydrocholesterol [de-hi″dro-k -les′t r-ol] 7-dehydrocholesterol; a sterol found in the skin that, when properly irradiated by ultraviolet rays, forms vitamin D.

  • activated 7-d. cholecalciferol.

• dehydrocholic acid [de-hi″dro-ko′lik] a semisynthetic bile acid used to increase output of bile by the liver and the filling of the gallbladder. Preparations of this acid are used to aid the digestion of fats and increase absorption of fat-soluble vitamins.

• 11-dehydrocorticosterone [de-hi″dro-kor″tľ-kos′t r-ōn] one of the least active of the glucocorticosteroids produced by the adrenal cortex.

• dehydroepiandrosterone (DEHA) [de-hi″dro-ep″e-an-dros′t r-ōn] an androgen C19 steroid produced by the adrenal cortex occurring in normal human urine and synthesized from cholesterol.

• dehydrogenase [de-hi′dro-j n″ās] an enzyme that mobilizes the hydrogen of a substrate so that it can pass to a hydrogen acceptor, such as NAD+ or FAD+.

  • alcohol d. dimeric enzyme protein of the liver catalyzing the NAD+-linked dehydrogenation of ethanol to acetaldehyde.
  • glucose-6-phosphate d. see glucose-6-phosphate dehydrogenase.
  • glutamate d. (GLDH, GMD, GD), glutamic d. an enzyme that catalyzes the reversible reaction of glutamic acid into 2-oxoglutaric acid and ammonia, which is then converted to urea. High concentrations occur in the liver of sheep, cattle, horses, dogs, birds, and exotic species, such as amphibians and reptiles, and increased serum concentration is an indicator of hepatocellular damage.
  • l-iditol d. (ID) a liver-specific enzyme; serum determinations have been used in the horse to detect hepatocellular damage. Called also sorbitol dehydrogenase, SDH.
  • isocitrate d. (ICD) an enzyme found in high concentrations in many tissues. Exists in two major forms, an NAD+-dependent ICD that functions in the tricarboxylic acid cycle to convert isocitrate to a-ketoglutarate and CO₂ and a NADP+-dependent ICD associated with fat synthesis in adipose tissue and lactating mammary gland of ruminants or with steroidogenesis in endocrine tissues. Serum concentrations have been used to detect hepatocellular damage, but it is not highly specific.
  • lactate d. (LDH, LD), lactic acid d. an enzyme that catalyzes the reversible conversion of pyruvate to lactate, the final step in the glycolysis pathway in anerobic conditions. It is widespread in tissues and is particularly abundant in kidney, skeletal muscle, liver, and myocardium. It appears in elevated concentrations when these tissues are injured. See also mouse lactic dehydrogenase elevating virus.
  • lactate d. agent see Arterivirus.
  • lactate d. test a high concentration in milk used as an indicator of the presence of mastitis in the quarter.
  • polyol d. see l-iditol dehydrogenase (above).
  • sorbitol d. (SDH) see l-iditol dehydrogenase (above).

• dehydrogenate [de-hi′dro-j n-āt] to remove hydrogen from.

• dehydrongaione one of the hepatotoxic furanosesquiterpenes found in Myoporum spp. and Eremophila spp. of plant family Myoporaceae.

• dehydropiandrosterone weak androgen secreted by the testes and ovary.

• dehydroretinal [de-hi″dro-ret′ľ-n l] the aldehyde of dehydroretinol, derived from the visual pigment porphyropsin, found in freshwater fishes and certain vertebrates and amphibians; its metabolic role is analogous to that of rhodopsin in other animals.

• dehydroretinol [de-hi″dro-ret′ľ-nol] vitamin A₂, the form, C₂₀H₂₈O, of vitamin A found in the retina and liver of freshwater fishes and certain invertebrates and amphibians; it differs from retinol (vitamin A₁) in having one more conjugated double bond and has approximately one-third the biological activity of retinol. Called also retinol₂.

• Deinocerites a mosquito; vector of the virus of equine encephalomyelitis.

• deiodinase an enzyme that deiodinates two of the iodinated amino acids (iodothyrosines) within the thyroid gland. Selenium-dependent deiodinase I converts thyroxine (T4) to triiodothyronine (T3), the more active thyroid hormone.

• deionization [de-i″on-ľ-za′sh n] the production of a mineral-free state by the removal of ions.

• Deiter’s nucleus [di′terz] lateral vestibular nucleus in the brainstem.

• dejecta excrement.

• deka- deca-.

• delactation [de-lak″-ta′sh n] 1. weaning. 2. cessation of lactation.

• Delafondia see Strongylus.

• delacrimation [de-lak″rľ-ma′sh n] excessive flow of tears.

• DELAT direct enzyme-linked antiglobulin test.

• delay phenomenon [de-la′] a method of improving survival of skin grafts by raising large flaps in several stages before they are transferred.

• delayed [de-lād′] prolonged beyond the time normally required.

  • d. bone union a prolongation in the normal time for fracture healing.
  • d. hypersensitivity see delayed hypersensitivity.
  • d. neurotoxic effects a characteristic effect of the neurotoxins in industrial triaryl phosphates.
  • d. ovulation individual cows appear to have a prolonged follicular phase in their estral cycle, usually about 48 hours.
  • d. primary closure the surgical closing of a wound several days after the injury because the wound was initially too contaminated to close. Union of the wound closed in this manner is called healing by third intention.

• delead, de-lead [de-led′] to induce the removal of lead from tissues and its excretion in the urine by the administration of chelating agents.

• deleterious [del″ -tēr′e- s] injurious; harmful.

• deletion [d -le′sh n] in genetics, loss of genetic material from a chromosome.

• Deletrocephalus nematode genus of the superfamily Strongyloidea. Placed in the family Deletrocephalidae; found in the large intestine of the rhea.

• deliquescence [del″ľ-kwes′ ns] the condition of becoming moist or liquified as a result of absorption of water from the air.

• deliver [de-liv′ r] 1. to aid in parturition. 2. to remove, as a fetus, placenta.

• delivery [de-liv′ r-e] expulsion or extraction of the young and fetal membranes at birth.

• abdominal d. delivery of a neonate through an incision made into the uterus through the abdominal wall (cesarean section).

  • d. per vaginam normal birth, the fetus being delivered through the vagina; in contrast to a cesarean delivery.

• dell [del′] a small depression or dimple.

• dellen [del′ n] saucer-shaped excavations at the periphery of the cornea, usually on the temporal side.

• delmadinone acetate [del-mad′ľ-nōn] a progestin with antiestrogen and antiandrogen activity; used to suppress estrus and prevent pregnancy in dogs and cats and for treatment of benign prostatic hyperplasia, perianal tumors, and hypersexuality.

• delomorphous [del″o-mor′f s] having definitely formed and well-defined limits, as a cell or tissue.

• Delosperma genus of African plants in family Aizoaceae; contains soluble oxalates that cause nephrosis, edema. Called also mesems, vygies.

• delphinine [del′fľ-nēn] the best-known toxic alkaloid in Delphinium plants.

• Delphinium [del-fin′e- m] a genus of the plant family Ranunculaceae that includes the domesticated plants, delphinium and larkspur. Common cause of plant poisoning of cattle in North America. In the western US larkspur species are commonly described in three basic categories: plains, low, and tall, based on mature plant height and geographic distribution. They produce more than 18 different toxic diterpenoid alkaloids of which methyllycaconitine is believed the major toxic principle. It is a potent blocker of acetylcholine receptors and poisoned animals show muscle weakness, trembling, incoordination, stiff gait, straddled posture, and sudden collapse. Animals may die from respiratory paralysis or inhalation of regurgitated ruminal contents.

• delrad an algicide used in water supplies but is nontoxic at the concentrations used. Poisoning can occur with high doses.

• delta [del′t ] 1. the fourth letter of the Greek alphabet, Δ or δ; used in chemical names to denote the fourth of a series of isomeric compounds or the carbon atom fourth from the carboxyl group or to denote the fourth of any series. 2. a triangular area.

• delta-aminolevulinic acid see δ-aminolevulinic acid.

• delta-lysin one of the toxins produced by Staphylococcus aureus. Can cause dermonecrosis and destroy leukocytes, but its role in pathogenesis is unclear. Called also delta-toxin.

• delta-toxin delta-lysin of Staphylococcus aureus.

• Delta Society an international, non-profit organization promoting the human-animal bond through the use of animal-assisted activities and therapies.

• delta virus hepatitis D virus.

• deltamethrin [del″t -meth′rin] a synthetic pyrethroid.

• Deltaproteobacteria a class of gram-negative bacteria in the phylum Proteobacteria that includes the pathogenic species Lawsonia intracellularis, among others.

• Deltaretrovirus a genus in the family Retroviridae that includes exogenous, horizontally transmitted viruses found in several groups of mammals. Examples are bovine leucosis virus and primate T-lymphotropic virus.

• deltoid [del′toid] 1. triangular. 2. a muscle of the shoulder, between the scapula and the humerus that helps flex the shoulder and abducts the forelimb. See also Table 12.

• Demansia [de-man′se- ] a genus of venomous snakes of the Elapidae family.

• dematiaceous [de-mat″e-a′sh s] darkly pigmented; said of some fungi.

• deme [dēm] a population of animals (or plants) with very similar physical characteristics, which interbreed and occupy a limited geographic region. Called also a genetic population.

• demeanor behavior toward others; body language.

• demecarium [dem″ -kar′e- m] an indirect acting cholinergic agonist, used topically in the management of glaucoma; it is more potent and has longer duration of activity than pilocarpine.

• demeclocycline [dem″ -klo-si′klēn] a broad-spectrum tetracyclic antibiotic produced by a mutant strain of Streptomyces aureofaciens.

• demecolcine a cytotoxic alkaloid derived from Colchicum autumnale. It is used in chromosome analysis to arrest cell division in mid-metaphase so that the chromosomes can be stained by one of several techniques that produce a distinct pattern of light and dark bands along the chromosomes, and each chromosome can be recognized by its size and banding pattern.

• dementia [d -men′sh] loss of intellectual capacity accompanied by irrational behavior; in humans, usually a progressive disorder characterized by the loss of multiple cognitive abilities such as memory, speech and the inability to plan or initiate complex behavior.

• demephion an organophosphorus compound used as an insecticide and acaricide.

• Demerol [dem′ r-ol] a proprietary name for meperidine.

• demeton an organophosphorus insecticide used as a treatment for sucking lice. Consists of a mixture of two compounds; toxicity varies significantly, depending on their relative concentrations.

• demilune [dem′e-] crescent shaped.

• serous d. serous fluid-producing cells in glands; small canals connect the serous cells with the luminal surface.

• demineralization [de-min″ r-l-ľ-za′sh n] excessive elimination of mineral or organic salts from the tissues of the body.

• demodectic mange [dem-o-dek′tik] mange that in all species is caused by species-specific Demodex spp. Characterized by folliculitis with hair loss and often pustule formation anywhere on the body although the head, face, neck, and shoulders are most often affected. The cause of wastage due to the disease in large animals, mainly cattle, goats, and pigs, is the reduced value of the hide or pelt. See also demodecosis.

  D-09.

  

  Skin scraping with numerous Demodex canis mites.

• Demodex [dem′o-deks] a genus of mites parasitic within the hair follicles of the host; a member of the family Demodicidae. Some of the more common species are: D. aries (sheep), D. aurati (hamsters), D. bovis (cattle), D. caballi (horses), D. canis (dogs and cats), D. caprae syn. D. capri (infests goats), D. cati (infests cats), D. cornei (short bodied mite of dogs and cats), D. criceti (infests hamsters), D. cuniculi (rabbits), D. erinacei (hedgehogs), D. equi (horses), D. folliculorum (humans), D. gatoi (cats), D. ghanensis (cattle), D. inja (long bodied mite of dogs), D. merioni (gerbils), D. muscardini (dormice), D. ovis (sheep), D. phylloides (pigs).

• demodicosis [dem″ -dľ-ko′sis] demodectic mange; skin disease caused by mites in the genus Demodex. In dogs, it is associated with an abnormality of cell-mediated immunity. Most often, there are one or a few areas of hair loss in young dogs (localized), severe and resistant to all treatment. Adult-onset demodicosis is uncommon and often associated with an underlying disease, such as hypothyroidism, diabetes mellitus, hyperadrenocorticism, or neoplasia, or predisposing factor, such as immunosuppressive therapy. Secondary bacterial infection is very common, although clinical features can vary depending on the demodex species involved. Breeding with affected dogs is discouraged. Called also follicular mange, red mange, demodectic mange. See also pododemodicosis. In cats, clinical signs vary, ranging from localized disease, involving alopecia, erythema, and scaling similar to dogs, which may be localized around the head, face, and ears; otitis externa may be the principle complaint. Pruritus is often present and can be intense. Localized.

• demogram [de′mo-gram] a report of demographic results, usually in grid form.

• demographics [de″mo-graf′iks] the graphic representation of demographic results.

• demography [de-mog′r -fe] the statistical science dealing with populations, including matters of health, disease, births, and mortality. Strictly speaking the word refers to human populations but common usage includes lower animal populations.

• demucosation [de-mu″ko-sa′sh n] removal of the mucous membrane from a part.

• demulcent [de-mul′s nt] 1. soothing; bland. 2. a soothing mucilaginous or oily medicine or application.

  • alimentary d. substances of high molecular mass and good solubility that lubricate, coat and protect the mucosa of the upper alimentary tract. Usually they mask unpleasant tastes, stabilize emulsions, and act as suspension agents. Methyl cellulose, gum tragacanth, agar, mineral oil, and propylene glycol are used for this purpose.

• demyelinate [de-mi′ -lin′āt] to destroy or remove the myelin sheath of a nerve or nerves.

• demyelination [de-mi″ -lľn-a′sh n] destruction, removal, or loss of the myelin sheath of a nerve or nerves.

• demyelinization [de-mi″ -lin-ľ-za′sh n] see demyelination.

• denarcotize [de-nahr′ko-tīz] to remove narcotics or of narcotic properties.

• denaturant [de-na′ch r- nt] a denaturing agent.

• denaturation [de-na″ch r-a′sh n] 1. a change in the usual nature of a substance, as by the addition of methanol or acetone to alcohol to render it unfit for drinking. 2. disruption in protein and nucleic acid structure, produced by heat or certain chemicals, usually results in loss of function. In proteins, various noncovalent bonds are disrupted resulting in unfolding of the polypeptide chain; in nucleic acids hydrogen bonds between nucleotides are disrupted converting double-stranded molecules or parts of them into single-stranded forms.

  D-10.

  

  (A) Localized demodicosis on the foreleg of a dog. (B) Generalized demodicosis.

  • protein d. any nonproteolytic change in the chemistry, composition or structure of a native protein that causes it to lose some or all of its unique or specific characteristics.

• denature to deprive a substance of its natural qualities, e.g., by heating a protein to destroy its specific biological activity.

• dendr- word element. [Gr.] tree, treelike.

• dendraxon a nerve cell whose axon splits up into terminal filaments immediately after leaving the cell.

• dendric [den′drik] pertaining to a dendrite.

• dendriform [den′drľ-form] tree-shaped.

• dendrite [den′drīt] any of the threadlike extensions of the cytoplasm of a neuron; dendrites, which typically branch into treelike processes, compose most of the receptive surface of a neuron.

• dendritic [den-drit′ik] 1. branched like a tree. 2. pertaining to or possessing dendrites.

  • d. cell see dendritic cell.
  • d. reticular cell cells in lymph nodes participating in the provision of immune responses.
  • d. zone region of the neuron subjected to excitatory and inhibitory stimulation.

• Dendritobilharzia a genus of digenetic trematodes in the family Schistosomatidae.

  • D. pulverulenta found in the dorsal aorta of swans.

• Dendroaspis [den″dro-as′pis] see mamba.

• Dendrocnide genus of Asian, Australian and Pacific rainforest trees and shrubs in the family Urticaciae. Stinging hairs on the foliage cause severe and persistent pain on contact; horses have died from the effects; contains a toxic peptide moroidin. Includes D. excelsa, D. moroides, D. photinophylla. Called also Laportea spp., stinger, gympie.

• dendrodendritic see dendrodendritic synapse.

• dendrodochiotoxicosis [den-dro″do-ke-o-tok″sľ-ko′sis] see Dendrodocochium toxicum.

• Dendrodochium toxicum [den-dro-do′ke- m] toxic fungus that parasitizes stored grain; produces trichothecene mycotoxins verrucarin A and roridin E. Toxins from this organism cause a blood dyscrasia and degenerative visceral lesions. Also known as Myrothecium roridum.

• dendroid [den′droid] branched like a tree.

• dendron [den′dron] dendrite.

• Dendronessa galericulata mandarin duck. See Aix galericulata.

• denervation [de″n r-va′sh n] interruption of the nerve connection to an organ or part. See also denervating.

  • d. atrophy reduction in muscle fiber diameter as a result of discontinuation of nerve supply; always accompanied by paralysis; also called neurogenic atrophy.

• denervating the process of denervation.

  • distal d. disease condition seen in dogs affecting multiple peripheral nerves. Clinical signs are the result of distal motor axon degeneration within muscles and include tetraparesis, head and neck weakness, muscle atrophy, and possibly change in voice. Sensation is preserved. Recovery occurs over approximately 4–6 weeks, and the condition appears similar in some respects to idiopathic polyradiculoneuritis. The etiology is currently unknown.

• Denman Island disease [den′m n] severe disease of Pacific oysters in British Columbia, first reported in the vicinity of Denman Island, Canada. Diseases is caused by the protozoan Mikrocytos mackini, can affect Pacific (Crassostrea gigas) and Kumamoto oysters (Cr. sikamea), particularly older individuals in cold waters, and is characterized by abscess-like lesions.

• denominator the bottom line of a fraction; the base population on which population rates such as birth and death rates are calculated.

• dens [dens] pl. dentes [L.] a tooth or toothlike structure. The axis vertebra has a dens or odontoid process that protrudes from the cranial part of the body and articulates with the ventral arch of the atlas.

  • d. hypoplasia see atlantoaxial subluxation.
  • d. lupinus see wolf tooth.

• dense bars optically dense structures that occur in series aligned along the presynaptic membrane in neuromuscular junctions and contribute to active zones in muscle–nerve relationships.

• dense bodies round, amorphous bodies scattered through the cytoplasm of smooth muscle fibers; they appear to be points of attachment for myofilaments.

• densimeter, densitometer [den-sim′ -tr, den″sľ-tom′-t r] 1. an instrument for determining density or specific gravity of a liquid. 2. an instrument used for measuring photographic transmission and/or reflection density.

• densitometry [den″sľ-tom′ -tre] determination of variations in density by comparison with that of another material or with a certain standard.

• density [den′sľ-te] 1. the ratio of the mass of a substance to its volume. 2. the quality of being compact. 3. the quantity of matter in a given space. 4. the quantity of electricity in a given area, volume or time. 5. the degree of film blackening in an area of a photograph or radiograph.

  • population d. number of animals per unit of area; important in relation to the rate of spread of disease.
  • d. sampling see sampling.

• Densovirus a genus in the family Parvoviridae, subfamily Densovirinae, members of which infect insects.

• dental [den′t l] pertaining to the teeth.

  • d. abscess see periapical abscess.
  • d. aging estimating the age of an animal by its teeth. Significant especially in horses, cattle, and sheep, but it can only classify in relatively broad age categories. See also age determination.
  • d. alloy filling material used in the restoration of teeth.
  • d. arch there is an upper and a lower dental arch carrying the maxillary and mandibular teeth, except in ruminants where the incisor sector of the upper arch is absent.
  • d. bud group of cells at the periphery of the dental lamina; tooth development is commonly divided into the initiation stage, the bud stage, the cap stage, the bell stage, and finally maturation; the bud stage is characterized by the appearance of a tooth bud where epithelial cells proliferate into the ectomesenchyme of the jaw.
  • d. chisel instrument used with a pushing technique during periodontal treatment in interproximal spaces of teeth.
  • d. cyst see periapical cyst, dentigerous cyst.
  • d. discoloration occurs as a result of medication with tetracyclines when the teeth are still in the development stage, in cases of porphyrinuria, and in small discrete lesions in association with fluorosis, again when the poisoning occurred in the pre-eruption stage. Congenital absence of sufficient dentin and enamel, as occurs in calves, causes the teeth to look pink because of vascularity of the pulp.

    D-11.

    

    Dental (dentigerous) cyst with a draining tract in a horse.

  • d. fistula a sinus tract that originates from a diseased tooth; discharging from the tooth through the skin covering the face, the gingiva or alveolar mucosa (most often at the mucogingival junction) into the mouth, the paranasal sinuses, or the nasal cavity. See also malar abscess, gum boil. See also malar abscess, gum boil.
  • d. follicle a sac containing the developing tooth (enamel organ and dental papilla); it differentiates into the periodontal ligament and may be the precursor of other cells of the periodontium, including osteoblasts, cementoblasts, and fibroblasts.
  • d. formula an alphanumeric system for listing the number, type (I = incisor, C = canine, P = premolar, M = molar), and position (upper or lower) of teeth. See Table 18.
  • d. fracture/fissure breaking of a tooth; also called tooth fracture; usually the result of traumatic injury. May involve the enamel, crown or root, or any combination. Causes great discomfort, unwillingness to close the jaw or chew; often the mouth sags open and saliva is allowed to drool.
  • d. hoe instrument used with a pulling technique during periodontal treatment to remove supragingival and subgingival plaque and calculus.
  • d. impaction failure of teeth to erupt because of contact with a physical barrier.
  • d. interlock malocclusion in immature animals often creates an adverse dental interlock that results in trauma and interferes with proper growth of the jaws. In dogs, eruption of deciduous and permanent canine teeth may cause them to interlock after which the maxilla and mandible are forced to grow at the same rate. Can result in prognathism, narrow mandible, or brachygnathism.
  • d. lamina band of epithelial tissue seen at the beginning of tooth development that thickens and invaginates to form tooth buds. See also dental bud.
  • d. luxation a clinically or radiographically evident displacement of the tooth within its alveolus. Called also tooth luxation.
  • d. mirror an instrument used to provide indirect vision to lesions and areas of interest that are not approachable from the front or side of the mouth (e.g., the palatal/lingual/distal surfaces of teeth, particularly of the maxillary and mandibular molars in dogs), reflect light onto and magnify areas of interest, retract the cheeks to the side, push the tongue medially or ventrally, and lift the soft palate dorsally or pull it rostroventrally, and protect oral soft tissues (e.g., placing the mirror as a barrier between the sublingual area and the mandibular cheek teeth when using power equipment on those teeth).
  • d. numbering systems see Palmer dental notation, Triadan system.
  • d. pad the thick layer of mucous membrane covered connective tissue that replaces the upper incisor teeth in the ruminant.
  • d. papilla condensation of ectomesenchymal cells that lies below a cellular aggregation known as the enamel organ and gives to the dentin and pulp of a developing tooth.
  • d. records legal documents that contain information about the patient’s history, diagnosis and treatment of dental and oral disease.
  • d. resorption see tooth resorption.

    D-12.

    

    Dental pad in a cow. (From Holtgrew-Bohling, K. Large animal clinical procedures for veterinary technicians, ed 2, St Louis, 2012, Mosby.)

  • d. star the mark on the occlusal surface of an equine incisor (labial to the enamel spot that is the deepest part of the infundibulum) caused by the appearance of tertiary dentin, as the tooth wears.
  • d. tartar see dental calculus.

• dentalgia [den-tal′j ] toothache.

• dentate [den′tāt] notched, toothed; tooth-shaped.

• dentia [den′sh ] a condition relating to development or eruption of the teeth.

  • d. precox premature eruption of the teeth; an outdated term.
  • d. tarda delayed eruption of the teeth, beyond the usual time for their appearance; an outdated term.

• dentibuccal [den″tľ-buk′ l] pertaining to the cheek and teeth.

• denticle [den′tľ-k l] a small toothlike structure.

• dentification [den″tľ-fľ-ka′sh n] formation of tooth substance.

• dentigerous [den-tij′ r- s] bearing teeth.

  • d. cyst odontogenic cyst initially formed around the crown of a partially erupted or unerupted tooth; also called follicular cyst or tooth-containing cyst.

• dentilabial [den″tľ-la′be- l] pertaining to the teeth and lips.

• dentilingual [den″tľ-ling′w l] pertaining to the teeth and tongue.

• dentin [den′tin] mineralized tissue surrounding the pulp and containing dentinal tubules that radiate outward from the pulp to the periphery; making up the bulk of the tooth; continually produced by odontoblasts (initially as predentin that is unmineralized dentin matrix that later becomes mineralized dentin) throughout the life of a vital tooth; comprised of 70% mineral (calcium hydroxyapatite), 20% protein and lipid, and 10% water; porous, with approximately 45,000 dentinal tubules per square millimeter in coronal dentin.

  • primary d. first dentin produced during development of the tooth.
  • sclerotic d. transparent dentin characterized by mineralization of the dentinal tubules as a result of an insult or normal aging.
  • secondary d. dentin produced until root formation is completed (e.g., dogs, cats) or the tooth comes into occlusion (e.g., horses).
  • tertiary d. dentin produced as a result of a local insult; can be reactionary (produced by existing odontoblasts) or reparative (produced by odontoblast-like cells that differentiated from pulpal stem cells as a result of an insult).

• dentinal [den′tľ-n l] pertaining to dentin.

  • d. bulge bulging of the crown of a tooth near the gingival margin to deflect food from the gingival sulcus.

    D-13.

    

    Dental star.

  • d. fiber outdated term for odontoblastic process, which is an extension of an odontoblast in a dentinal tubule. Called also Tomes’ fiber.
  • d. tubules parallel channels in dentin that contain odontoblastic processes, fluid, and nerves; forms during dentinogenesis and results from a part of the dentin-producing odontoblast staying in its location as the main body of the odontoblast moves toward the center of the tooth’s pulp.

• dentine [den′tēn] dentin.

• dentinoblastoma [den″tľ-no-blas-to′m ] see dentinoma.

• dentinoenamel junction [den″tľ-no- -nam′ l] the junction where dense, acellular enamel, being deposited by ameloblasts, meets the retreating ameloblastic front.

• dentinogenesis [den″tľ-no-jen′ -sis] the formation of dentin.

  • d. imperfecta disorder of tooth development characterized by discoloration and early wear of all teeth.

• dentinoma [den″tľ-no′m ] a tumor of odontogenic origin and consisting mainly of dentin.

• dentinosteoid [den″tľ-nos′te-oid] a tumor composed of or containing dentin and bone.

• dentinum [den-ti′n m] see dentin.

• dentistry [den′tis-tre] veterinary dentistry is a discipline within the scope of veterinary practice that involves the professional consultation, evaluation, diagnosis, prevention, treatment (non-surgical, surgical, or related procedures) of conditions, diseases, and disorders of the oral cavity and maxillofacial area and their adjacent and associated structures; it is provided by a licensed veterinarian, within the scope of his/her education, training, and experience, in accordance with the ethics of the profession and applicable law. See also beakology.

  • conservative d. involved with the preservation of natural teeth.
  • equine d. the practice of veterinary dentistry performed in equids (genus Equus: horses, asses and zebras).
  • operative or restorative d. a specialty in dentistry and oral surgery that is concerned with the art and science of the diagnosis, treatment and prognosis of defects of teeth that do not require prosthodontic crowns for correction.

• dentition [den-tish′ n] the teeth in the dental arch; ordinarily used to designate the natural teeth in position in the alveoli. See also teeth.

  • deciduous d. the complement of teeth that erupt first and are later succeeded by the permanent teeth.
  • milk d. the dentition of sucklings; the deciduous teeth.
  • mixed d. the complement of teeth in the jaws after eruption of some of the permanent teeth, but before all the deciduous teeth are shed.
  • permanent d. secondary teeth in monophyodont or diphyodont species; in the latter it is preceded by deciduous teeth.
  • temporary d. the temporary or first set of teeth in animals with diphyodont dentition. See also deciduous teeth.

    D-14.

    

    Skull of an adult dog showing the permanent dentition.

• dent(o)- word element. [L.] tooth, toothlike.

• dentoalveolar [den″to-al-ve′ -l r] pertaining to a tooth and its alveolus.

  • d. abscess see alveolar abscess.

• dentoalveolitis [den″to-al″ve- -li′tis] periodontitis.

• dentofacial [den″to-fa′sh l] of or pertaining to the teeth and alveolar process and the face.

• dentulous [den′tu-l s] having natural teeth.

• denture [den′ch r] a complement of teeth, either natural or artificial; ordinarily used to designate an artificial replacement for the natural teeth and adjacent tissues. Isolated reports of use in dogs.

• denucleation [de-noo″kle-ā′sh n] removal of the nucleus.

• denudation [den″u-da′sh n] the stripping or laying bare of any part.

• deodorant [de-o′d r- nt] 1. destroying or masking odors. 2. an agent that masks offensive odors.

• deodorize [de-o′d r-īz] to neutralize or absorb odor.

• deorsumversion [de-or″s m-vur′zh n] the simultaneous turning downward of both eyes.

• deossification [de-os″ľ-fľ-ka′sh n] loss or removal of the mineral elements of bone.

• deoxidation [de-ok″sľ-da′sh n] the removal of oxygen from a chemical compound.

• deoxy- a chemical prefix designating a compound containing one less atom of oxygen than the reference substance. See also words beginning desoxy-.

• deoxycholate [de-ok″se-ko′lāt] any salt of deoxycholic acid.

• deoxycholic acid [de-ok″se-ko′lik] one of the bile acids, capable of forming soluble, diffusible complexes with fatty acids, and thereby allowing for their absorption in the small intestine.

• deoxydexamethasone [de-ok″se-dek-s -meth′ -sōn] desoximetasone.

• deoxygenation [de-ok″sľ-j n-a′sh n] the act of depriving of oxygen.

• 2-deoxy-d-glucose an antimetabolite of glucose with antiviral activity; it acts by inhibiting the glycosylation of glycoproteins and glycolipids; it has been used for treatment of genital herpesvirus infections in humans.

• deoxyhemoglobin [de-ok″se-he″mo-glo′bin] hemoglobin not combined with oxygen, formed when oxyhemoglobin releases its oxygen to the tissues.

• deoxynivalenol [de-ok″se-nľ-val′ -nol] trichothecene toxin produced by the fungus Fusarium graminearum and other fungi. Called also DON, food refusal factor, emetic factor, vomitoxin.

• deoxyribonuclease (DNase) [de-ok″se-ri″bo-noo′kle-ās] an enzyme that catalyzes the hydrolysis (depolymerization) of deoxyribonucleic acid (DNA). Group A streptococci produce extracellular DNases, and commercially available DNase agar may be used to identify pathogenic species.

• deoxyribonucleic acid [de-ok″se-ri″bo-noo-kle′ik] a nucleic acid occurring in cells as the basic structure of the genes. DNA is present in all body cells of every species, including unicellular organisms and DNA viruses. The structure of DNAwas first described in 1953 by J.D. Watson and F.H.C. Crick. DNA molecules are long linear polymers of small molecules called nucleotides, each of which consists of one molecule of the five-carbon sugar deoxyribose bonded to a phosphate group and to one of four heterocyclic nitrogenous compounds referred to as bases. A single strand of DNA is made by linking the nucleotides together in a chain with bonds between the sugar and phosphate groups of adjacent nucleotides. It thus consists of a backbone of alternating sugar and phosphate groups with a base attached to each sugar as a side chain. The four bases are two purines, adenine (A) and guanine (G), and two pyrimidines, cytosine (C) and thymine (T). Single-stranded DNA can be synthesized with any specified sequence of bases, but in living cells the base sequence has a meaning; it specifies the amino acid sequence of all of the polypeptides and proteins made by the cell. And since all of the enzymes that catalyze biochemical reactions are proteins, the DNA contains the specifications for all of the biochemistry and structure of the cell. The chemical basis of the genetic code lies in the ability of the bases to form hydrogen bonds with each other. Unlike the covalent bonds holding together the atoms of a single strand of DNA, hydrogen bonds are weak and easily broken and reformed. Hydrogen bonding is governed by the base pairing rule: A always bonds with T, and C always bonds with G. A and T (or C and G) are called complementary bases. The genetic information is read and preserved by the matching up of complementary bases. In cells, the DNA is double stranded. The configuration of the DNA molecule resembles a ladder in which the sides are the sugar–phosphate backbones, which are antiparallel (they run in opposite directions), and the rungs are hydrogen-bonded complementary bases; thus, the entire sequence along the two strands is complementary. This whole structure is twisted so that the two strands form a double helix. Once before each cell division, a group of proteins splits the two strands apart, and as complementary nucleotides bond to the bases of each strand they are jointed to form a new strand. This process is called replication. It results in the exact duplication of the DNA molecule, because each strand serves as a template (pattern) for the synthesis of its complementary strand. When the cell divides, one copy goes to each daughter cell. Thus, the genetic information is passed on from generation to generation without change except for rare mutations, which result from copying errors or incorrectly repaired breaks in the DNA molecule that change the base sequence. The reading of the genetic code involves two processes: transcription and translation. In transcription, a length of DNA is used as a template to make a complementary strand of messenger RNA (mRNA). RNA (ribonucleic acid) is a nucleic acid like DNA. The only differences are that the sugar, ribose, has an extra oxygen atom, and the pyrimidine base, uracil (U), which also pairs with adenine, replaces thymine. In translation, the mRNA molecule is read by a structure called a ribosome, which produces the polypeptide specified by the mRNA message. The genetic code is a triplet code. Every triplet of bases along the strand specifies a single amino acid. There are 64 possible triplets (codons) that can be formed from the four bases. Each one specifies that one of 20 different amino acids be inserted in a growing polypeptide chain or marks either the start or the end of a chain. Two other types of RNA are involved in translation. Ribosomal RNA (rRNA) forms a large part of the ribosome. Transfer RNA (tRNA) is the means by which codons are matched with amino acids. tRNAs are small molecules with several self-complementary sections so that they fold up into a compact structure owing to bonding between complementary bases. One end of the molecule is a three-base anticodon, which bonds to its complementary codon on mRNA molecules. The other end is recognized by a specific enzyme which attaches the correct amino acid to it. During translation, the ribosome proceeds along the mRNA molecule, and, as each codon is matched by a specific tRNA, the amino acid it carries is transferred to the growing polypeptide chain, and the process is repeated until the ‘stop’ codon is reached. Like the mRNA molecules, rRNA and tRNA molecules are formed on DNA templates; the genetic material contains not only the information for polypeptide sequences but also for rRNA and tRNA sequences. The chromosomes of mammalian cells contain 3 × 10⁹ base pairs, which is enough to code for the 100,000 or so enzymes and structural proteins. Less than 10% of the DNA codes for proteins and RNA, the rest is noncoding, also referred to as ‘junk’ DNA and is of uncertain purpose. DNA is the molecule that directs all of the activities of living cells, including its own reproduction and perpetuation in generation after generation.

• deoxyribonucleoprotein [de-ok″se-ri″bo-noo″kle-o-pro′tēn] a nucleoprotein in which the sugar is d-2-deoxyribose.

• deoxyribonucleoside [de-ok″se-ri″bo-noo′kle-o-sīd] a nucleoside having a purine or pyrimidine base bonded to deoxyribose.

• deoxyribonucleotide [de-ok″se-ri″bo-noo′kle-o-tīd] a nucleotide having a purine or pyrimidine base bonded to deoxyribose, which in turn is bonded to a phosphate group.

• deoxyribose [de-ok″se-ri′bōs] an aldopentose found in deoxyribonucleic acid, deoxyribonucleotides, and deoxyribonucleosides.

• depasture to feed livestock by grazing them on pasture.

• Dependoparvovirus [d -pen′do-vi″r s] a genus in the family Parvoviridae, subfamily Parvovirinae that includes the adeno-associated viruses.

• dephosphophosphorylase the deactivated form glycogen phosphorylase, the regulatory hydrolytic enzyme involved in the phosphorolytic breakdown of glycogen to glucose.

• dephosphorylation [de-fos″for- -la′sh n] hydrolytic removal of a phosphate group from an organic molecule.

• depigmentation [de-pig″m n-ta′sh n] removal of pigment; usually refers to melanin. See also hypopigmentation.

  • nasal d. occurs in dogs with a normal, darkly pigmented nasal planum at birth but later fades to brown or a pale gray-white. Called also ‘Dudley nose’, the cause is unknown, but it may be a form of vitiligo. Also occurs as a seasonal loss of pigmentation, usually during winter months, in some breeds, including Siberian huskies, Golden retrievers, Labrador retrievers, and Bernese mountain dogs, where it is called ‘snow nose’. Not to be confused with diseases such as nasal solar dermatitis, uveodermatologic syndrome, autoimmune skin diseases involving the nasal planum in which there is loss of pigment, but usually with other changes present.

• depilate [dep′ľ-lāt] to remove hair.

• depilation [dep″ľ-la′sh n] removal of hair by the roots. See also epilation.

  • chemical d. the use of chemicals applied externally or internally to remove hair. See also chemical shearing.

  D-15.

  

  Nasal depigmentation in a Labrador retriever. (Dudley nose).

• depilatory [d -pil′ -tor″e] 1. having the power to remove hair. 2. an agent that removes or destroys the hair.

• depletion syndrome [d -ple′sh n] chronic water and electrolyte deficits.

• depluming removing the feathers of birds.

  • d. itch Cnemidocoptesgallinae. Called also depluming mite, depluming scabies.
  • d. scabies see depluming itch (above).

• depolarization [de-po″l r-ľ-za′sh n] the process or act of neutralizing polarity as in the decrease of membrane potential.

  • myocardial d. the conducted cardiac impulse transiently reverses membrane polarity. In this depolarized phase the myocardium is incapable of further contraction.

• depolarize [de-po′l r-īz] the act of depolarization.

• depolarizing agent a drug that causes depolarization. Usually applied to those used to produce neuromuscular blockade and muscle paralysis.

• depolymerization [de″p -lim″r-ľ-za′sh n] the breakdown of a polymer into its simpler components.

• depopulation [de″pop-u-la′sh n] removal of all animals from the particular environment.

  • herd d. disposal of all animals in the herd.

• deposit [de-poz′it] 1. sediment or dregs. 2. extraneous inorganic matter collected in the tissues or in an organ of the body.

• depot [de′po] a body area in which a substance, e.g., a drug, can be accumulated, deposited, or stored and from which it can be distributed.

  • fat d. a site in the body in which large quantities of fat are stored, as in adipose tissue.

• l-deprenyl [dep′r -n l] see selegiline.

• depressant [de-pres′ nt] 1. diminishing any function or activity. 2. an agent that retards any function, especially a drug that acts on the central nervous system to depress activity at all levels by stabilizing neuronal membranes. CNS depressants, e.g., barbiturates and inhalational anesthetics, are used as sedatives, hypnotics, and anesthetics.

• depressed [de-prest′] carried below the normal level; associated with depression.

• depression [de-presh′ n] 1. a hollow or depressed area. 2. a lowering or decrease of functional activity. 3. decreased interest in surroundings, decreased response to external stimuli. The least degree in a range of depressive mental states. See also somnolence, lassitude, narcolepsy, catalepsy, syncope, coma.

  • d. fracture important in the skull where shards of cranium might penetrate brain tissue, introduce infection, or cause pressure on the brain because of hemorrhage or hematoma formation.

• depressomotor [de-pres″o-mo′t r] 1. retarding or abating motor activity. 2. an agent that so acts.

• depressor [de-pres′ r] anything that depresses, as a muscle, agent or instrument, or an afferent nerve, whose stimulation causes a fall in blood pressure.

  • tongue d. an instrument for pressing down the tongue, usually for purposes of visualizing the soft palate and posterior pharynx. Not often used in examining animals.

• deracoxib a nonsteroidal anti-inflammatory in the coxib class; used as an anti-inflammatory and analgesic agent in dogs and cats.

• deradelphus [der″ -del′f s] a conjoined twins joined at or near the navel, and having one head.

• derangement [de-rānj′m nt] 1. mental disorder. 2. disarrangement of a part or organ.

• Derbyshire Gritstone large framed sheep, polled, black and white marked face and legs that are free of wool. One of the oldest of British sheep breeds, noted for its hardiness.

• deregistration [de″rej-is-tra′sh n] removal of right to practice by local registering body, usually as a disciplinary measure because of professional misconduct.

• deregulation [de″reg-u-la′sh n] removing restrictions and government controls on animal management and animal disease.

• derencephalus [der″en-sef′ -l s] a fetus with a rudimentary skull and bifid cervical vertebrae, the brain resting in the bifurcation.

• derepression [de″re-presh′ n] 1. elevation of the concentration of an enzyme above the normal, either by lowering the corepressor concentration or by a mutation that decreases the formation of aporepressor or the response to the complete repressor. 2. the inhibition of the repressor substance produced by the regulator genes with the result that the operator gene is free to initiate the process of polypeptide formation.

• Derf needle holder a fine instrument used for grasping and passing suture needles in ophthalmic surgery.

• derma [dur′m ] the corium, or true skin.

• Dermacentor [dur″m -sen′t r] a genus of ticks parasitic on various animals; can act as, an vectors of disease-producing microorganisms; member of the family Ixodidae.

  • D. albipictus a one-host tick that transmits anaplasmosis and possibly Rocky Mountain spotted fever. Parasitizes moose mostly but also other wild ruminants and pastured livestock. Called also moose tick or winter tick.
  • D. andersoni a species of tick common in the western US, parasitic on numerous wild mammals, most domestic animals, and humans. It is a vector of Rocky Mountain spotted fever, tularemia, Colorado tick fever, and Q fever in the US, and is one of the causes of tick paralysis in the US.
  • D. halli, D. marginatus, D. nuttalli, D. silvarum miscellaneous ticks of little importance to animals.
  • D. nigrolineatus a one-host tick occurring mostly on white-tailed deer, but also on pastured livestock. Called also brown winter tick.
  • D. nitens a one-host tick that parasitizes horses mostly and is the vector of equine piroplasmosis; predisposes animals to screw-worm attack. Called also tropical horse tick, Anocentor nitens.
  • D. occidentalis a three-host tick found on many animals. Immature forms are on rodents. Transmits anaplasmosis, Colorado tick fever, Q fever, tularemia, causes tick paralysis. Called also Pacific Coast tick.
  • D. parumapterus a vector of Rocky Mountain spotted fever.
  • D. reticulatus a three-host tick that transmits equine piroplasmosis.
  • D. variabilis a three-host tick that transmits Anaplasma marginale in cattle, tularemia in humans, is the chief vector of Rocky Mountain spotted fever in the central and eastern US and causes tick paralysis in the dog. The dog is the principal host of the adult forms, but also parasitic on cattle, horses, rabbits, and humans. Called also American dog tick.
  • D. venustus see Dermacentor andersoni (above).

• dermal [dur′m l] pertaining to the portion of the skin beneath the level of the epidermis.

  • d. asthenia called also dermal fragility syndrome; see cutaneous asthenia.
  • d. fragility syndrome see dermal asthenia (above).
  • d. melanocytosis the neoplastic form of melanoma in horses with multiple lesions in the skin and in internal organs; common in gray horses and mules.

    D-16.

    

    Dermacentor andersoni. Courtesy of CDC/Dr. Christopher Paddock; Photo: J. Gathney.

  • d. network sensory nerves of the dermis.
  • d. papillae fingerlike processes invading the epidermis from the dermis, that serve to anchor the overlying epidermis in place; they are most numerous over hairless skin.

• Dermanyssidae [dur″m -nis′ľ-de] family of parasitic mites. Includes Dermanyssus, Ornithonyssus and Pneumonyssoides spp.

• Dermanyssus gallinae [dur″m -nis′ s] a member of the genus of the family Dermanyssidae of mites. A major parasite of domestic fowls but also occurs on other birds including aviary and wild colonies. Causes death due to anemia. A vector for spirochetosis of fowls and possibly the equine encephalitides. A common chance parasite of humans from heavy infestations in urban bird colonies. Called also red mite.

• derm(at)- word element. [Gr.] relationship to the skin.

• dermatan sulfate [dur″m -tan] a component of the acellular ground substance of skin.

• dermatitides [dur″m -tit′ľ-dēz] plural of dermatitis; inflammatory conditions of the skin considered collectively.

• dermatitis [dur″m -ti′tis] inflammation of the skin. See also dermatosis.

  • actinobacillary d. rare disease in cattle; large ulcers discharging yellow pus or nodules, on lymphatics with local lymph node enlargement.
  • acute moist d. see pyotraumatic dermatitis.
  • allergic contact d. see allergic contact dermatitis.
  • allergic inhalant d. see canine atopy.
  • annular d. inflammation and crusting in an annular pattern is characteristic of dermatophytosis (ringworm), particularly in pigs.
  • atopic d. see canine atopy.
  • canine eosinophilic d. erythematous and edematous, variably pruritic, macules and plaques on the ears, thorax and abdomen; there is a marked infiltration of eosinophils. Believed to be a hypersensitivity reaction. There are similarities with eosinophilic cellulitis (Wells syndrome) in humans.
  • cercarial d. see Trichobilharzia.
  • cheyletiella d. see cheyletiellosis.
  • chronic radiant heat d. erythema, alopecia and hyperpigmentation in areas exposed to moderate heat, especially radiant heat, over a long period of time. Reported in dogs and cats. Called also erythema abigne.
  • contagious pustular d. of sheep see contagious ecthyma.
  • coronet d. part of several infectious mucosal diseases of cattle; also in equine pemphigus.
  • d. crustosa exudative epidermitis.
  • digital d. characterized by round, proliferative, painful, raised lesion on the back of the lower pastern just above the digital cleft, most commonly on hindlimb of cattle, especially heifers. Invasive treponemes displaying large genotypic and phenotypic diversity and representing three phylogroups within the genus (Treponema medium/T. vinventii-like; T. phagedenis-like; T. denticola/T. putidum-like) can be isolated from affected feet. Responds well to antibiotic treatment, but in dairy cattle, milk withholding requirements make this uneconomic, and treatment and control are usually with antibacterials in footbaths. Called also Mortellaro’s disease.
  • elaeophorial d. see elaeophoriasis.
  • equine contagious pustular d. see Canadian horsepox.
  • equine exfoliative eosinophilic d. see multicentric eosinophilic epitheliotrophic disease.
  • equine staphylococcal d. see equine staphylococcal dermatitis.
  • exfoliative d. of calves rarely reported widespread dermatitis including vesicles on the muzzle in very young calves; recovers spontaneously.
  • exudative d. of pigs see exudative epidermitis.
  • facial d. see sore nose, idiopathic facial dermatitis of Persian cats.
  • feline miliary d. a papular, crusting cutaneous reaction pattern of cats; lesions are located predominantly on the back, with varying degrees of pruritus. Hypersensitivity reaction to flea bites is a leading cause, but food and drug allergy, immune-mediated skin diseases, and infection by fungi or bacteria are among the many possible causes. Called also scabby cat disease.
  • feline psychogenic d. see idiopathic hyperesthesia syndrome.
  • feline solar d. see solar dermatitis (below).
  • fibrosing d. dermatitis sufficiently severe to affect deep layers of the dermis results in scarring of the skin due to excessive fibrous tissue formation.
  • filarial d. see stephanofilarosis, onchocercosis.
  • focal ulcerative d. manifest by ulcers in the unfeathered anterior breast skin of 4- to 5- month-old male turkeys. The incidence is influenced by litter type. Called also breast buttons.
  • fold d. moisture, friction and secondary infection in body folds such as facial fold in brachycephalic dog breeds, tail fold in dog breeds with extremely short, often screw, tails, lip fold in spaniels and hounds, perivulvar fold in obese bitches, and in the Shar pei, all over the body. Called also intertrigo.
  • grain itch mite d. a transient, superficial dermatitis, mostly about the head in horses; may be all over the body in pigs. Caused by Pediculoides ventricosus or Tyroglyphus.
  • granular d. swamp cancer.
  • d. herpetiformis chronic dermatitis in humans marked by successive crops of grouped, symmetrical, erythematous, papular, vesicular, eczematous, or bullous lesions, accompanied by itching and burning; a granular deposition of IgA immunoglobulin around the lesion almost always occurs. Occurs rarely in dogs.
  • idiopathic caprine d. alopecic, exudative dermatitis of pygmy goats of all ages affecting head, perineum, ventral abdomen.
  • infectious d. of piglets see contagious porcine pyoderma.
  • inhalant d. see canine atopy.
  • interdigital d. see interdigital dermatitis.
  • interface d. a histopathological pattern of inflammatory skin disease with the dermoepidermal junction obscured by hydropic degeneration and/or lichenoid cellular infiltrate.
  • intertriginous d. see fold dermatitis (above).
  • intraepidermal pustular d. see equine allergic dermatitis.
  • lipfold d. see fold dermatitis (above).
  • Malassezia d. a pruritic, seborrheic skin disease of dogs, particularly some breeds including West Highland white terriers, Shetland sheepdogs, Poodles, and Cocker spaniels, and rarely cats, caused by colonization of the skin by the yeast, M. pachydermatis. There is usually an underlying cause such as atopy or bacterial pyoderma.
  • d. medicamentosa an eruption or solitary skin lesion caused by a drug taken internally.
  • miliary d. see feline miliary dermatitis (above).
  • moist d. of rabbits the rabbit’s pendulous dewlap keeps getting wet and develops a moist dermatitis as a result. Called also slobbers, wet dewlap.
  • mycotic d. see mycotic dermatitis.
  • nasal d. see sore nose.
  • nasal solar d. see solar dermatitis (below), collie nose.
  • ovine interdigital d. see ovine footrot.
  • ovine staphylococcal d. ulcerative dermatitis of the face of adult sheep and young lambs caused by a dermatopathic strain of Staphylococcus aureus. Called also ovine staphylococcal pyoderma.
  • pastern d. see greasy heel, lymphedema.
  • pelodera d. caused by larvae of the free-living nematode Pelodera strongyloides and characterized by alopecia, itching, thick, scurfy skin, and pustules (~0.5 in. in diameter) that contain the larvae.
  • photocontact d. allergic contact dermatitis caused by the action of sunlight on skin sensitized by contact with a substance capable of causing this reaction.
  • photosensitive d. is confined to the dorsal parts of the body exposed to the sunlight, and to parts with little or no pigment and the least hair or wool covering. Develops when photodynamic agents are activated by ultraviolet light (wavelength of 200–400 nm) as they circulate through superficial vessels of non-pigmented skin to produce local tissue injury via formation of oxygen free radicals that subsequently damage cell membranes and DNA. The dermatitis is diffuse and often sufficiently severe to kill the animal. Initially there is itching and rubbing, then edema, followed by weeping, then necrosis or gangrene. Additional lesions may be on the undersurface of the tongue, at the mucocutaneous junction at the lips and on the lateral aspects of the teats.
  • plastic dish d. a contact dermatitis caused by plastic feeding dishes to which a dog is allergic.
  • porcine juvenile pustular psoriasiform d. see pityriasis rosea.
  • potato d. see potato dermatitis.
  • primary-irritant d. contact dermatitis (see above) induced by a substance acting as an irritant rather than as a sensitizer or allergen.
  • proliferative d. see strawberry footrot.
  • psoriaform, psoriasiform d. of swine see pityriasis rosea.
  • pyotraumatic d. see acute moist dermatitis (above).
  • d.–pyrexia–hemorrhage syndrome a pruritic, papulocrustous dermatitis in dairy cows that is accompanied by fever and hemorrhage from the nose and anus. Mycotoxins, particularly citrinin, have been implicated as the cause.
  • rhabditic d. see pelodera dermatitis (above).
  • seasonal allergic d. see atopy, equine allergic dermatitis.
  • seborrheic d., d. seborrheica a chronic, usually pruritic, dermatitis with erythema, dry, moist or greasy scaling, and yellow crusted patches on various areas, with exfoliation of an excessive amount of dry scales (dandruff) or encrustations of sebum on the skin. See also exudative epidermitis (pigs), greasy heel (horses), flexural seborrhea (cows), seborrhea.

    D-17.

    

    Clinical presentation of different stages of digital dermatitis. (A) M1 (within red oval): early stage lesion; mostly 0–2 cm; not painful on palpation. (B) M2 (active infection): classical ulcerative stage; diameter >2 cm, often painful on palpation. (C) M3: healing stage after local therapy; lesion is covered by a scab; not painful on palpation. (D) M4: chronic stage; dyskeratosis or proliferation of surface; generally not painful on palpation.

  • solar d. a chronic, inflammatory reaction on white or lightly pigmented and exposed skin caused by sunlight. Most commonly seen on the ear tips, nose, and eyelids of white cats and the nose of collie dogs or related breeds. Squamous cell carcinomas sometimes develop in affected skin. Called also nasal solar dermatitis, actinic dermatitis. See also Collie nose.
  • spongiotic d. perivascular inflammation with spongiosis.
  • summer d. see equine allergic dermatitis.
  • superficial necrolytic d. frequently associated with glucagon-secreting tumors of the pancreas and with cases of diabetes mellitus or chronic hepatitis; called also hepatocutaneous syndrome; lesions are erythematous, erosive, ulcerative, and crusted with marked hyperkeratosis of the footpads.
  • superficial pustular d. immature dogs may develop pustules on the inguinal or axillary skin, often in association with poor nutrition, systemic infection, or parasitism. In kittens, these may occur on the neck, caused by ‘mouthing’ by the queen.
  • trefoil d. see Trefoil dermatitis.
  • tyroglyphid d. see Tyroglyphus.
  • ulcerative d. of foals syndrome of unknown etiology with transient ulcerative dermatitis accompanied by thrombocytopenia and neutropenia affecting neonatal foals.
  • unilateral papular d. a disease of horses characterized by the appearance of many nodules or papules on one side of the neck and body. The lesions are eosinophilic folliculitis and perifolliculitis. The etiology and the unilateral distribution of the lesions are unexplained.
  • ventral midline d. small ulcers with hemorrhagic crusts and hair loss, located on the abdomen, particularly around the umbilicus, of horses; caused by biting flies and gnats.
  • vesicular d. see avian vesicular dermatitis.
  • viral contagious d. see contagious ecthyma.
  • viral papular d. see equine papular dermatitis.
  • x-ray d. radiodermatitis.

• Dermatobia [dur″m -to′be-] a genus of bot flies in the family Cuterebridae. Includes D. hominis, the larvae of which are parasitic in the skin of humans, mammals and birds, causing subcutaneous swellings with central holes. A major parasite of cattle in South America.

• dermatocele a disorder in which the skin and subcutaneous tissue hypertrophy so that the skin hangs in loose folds.

• dermatofibroma [dur″m -to-fi-bro′m] a fibrous tumor-like nodule of the skin.

• dermatofibrosarcoma [dur″m -to-fi″bro-sahr-ko′m] a fibrosarcoma of the skin.

• dermatofibrosis [dur″m -to-fi-bro′sis] a rare paraneoplastic syndrome in which multiple, firm, freely movable cutaneous and subcutaneous nodules of mature fibrous tissue, up to 2 in. in diameter, develop in middle age dogs. The highest incidence is in German shepherd dogs, in which it is inherited as an autosomal dominant trait. Affected animals show a high incidence of bilateral renal cystadenocarcinoma and females have multiple uterine and vaginal leiomyomas. Called also nodular dermatofibrosis.

• dermatoglyphics [dur″m -to-glif′iks] the surface features of skin, including wrinkles, folds, ridges and furrows; the science of fingerprints.

• dermatographia dermatographism.

• dermatographism [dur″m -tog′r-fiz″ m] urticaria due to physical allergy in which a pale, raised welt or wheal with a red flare on each side is elicited by stroking or scratching the skin with a dull instrument.

• dermatoheteroplasty [dur″m -to-het′ r-o-plas″te] the grafting of skin derived from an animal of another species.

• dermatohistopathology [dur″m -to-his-to-p-thol′ -je] the histopathological study of the skin.

• dermatologic, dermatological [dur″m -to-loj′ik, dur″m-to-loj′ľ-k l] pertaining to dermatology; of or affecting the skin.

• dermatologist [dur″m -tol′o-jist] a veterinarian who specializes in dermatology.

• dermatology [dur″m -tol′ -je] the specialty concerned with the diagnosis and treatment of skin diseases.

• dermatomal pertaining to a dermatome.

• d. mapping designation of regions of the body, the extent of each corresponding to the distribution of the dorsal root axons.

• dermatome [dur′m -tōm] 1. an instrument for cutting thin skin slices for grafting. 2. the area of skin supplied with afferent nerve fibers by a single dorsal spinal root. 3. the lateral part of an embryonic somite.

• air d. (1) an instrument designed for cutting split thickness skin grafts.

• Brown d. (1) an electric or pneumatic instrument used for cutting splitthickness skin grafts.

• dermatomegaly [dur″m -to-meg′ -le] see dermatocele.

• dermatomere [dur′m -to-mēr″] a segment of the embryonic integument.

• dermatomycosis [dur″m -to-mi-ko′sis] a fungal infection of the skin or of its appendages by one of the dermatophytes, Microsporum, Lophophyton, Nannizzia, Trichophyton or Epidermophyton. Also called dermatophytosis.

  D-18.

  

  (A) Facial fold dermatitis in a Bulldog. (B) Lip fold dermatitis in a dog. (C) Body fold dermatitis in a Shar pei.

  D-19.

  

  Photosensitive dermatitis with swelling of the face, eyelids and ears.

  D-20.

  

  Seborrheic dermatitis.

  D-21.

  

  Feline solar dermatosis in a white cat.

• dermatomyoma [dur″m -to-mi-o′m] a dermal leiomyoma.

• dermatomyositis [dur″m -to-mi″ -si′tis] an idiopathic inflammatory chronic skin disease involving the skin and muscles.

  • canine familial d. an inherited disease found in many breeds, but particularly Collies and Shetland sheepdogs. Starting at a young age, there is hair loss, alopecia, scaling, crusting, erosions, and scarring on the face, ear tips, pressure areas over the elbows, carpus and tarsus, and the tail. Myositis typically occurs months after the skin lesions and may be severe, causing a stiff gait, difficulty in chewing, and muscle atrophy, or be unrecognized except by biopsy. Megaesophagus may also occur.

• dermatopathic, dermopathic [dur″m -to-path′ik, dur″mo-path′ik] of the nature of or pertaining to any disease of the skin.

• dermatopathology [dur″m -to-p-thol′ -je] pathology that is especially concerned with lesions of the skin.

• dermatopathy [dur″m -top′ -the] any disease of the skin; dermopathy.

• Dermatophagoides [dur″m -tof″ -goi′dēs] a genus of mites of the family Epidermoptidae. Includes D. farinae and D. pteronyssinus (housedust mites).

• dermatophilosis [dur″m -to-fľ-lo′sis] a group of diseases caused by Dermatophilus spp. Includes mycotic dermatitis, strawberry footrot.

• Dermatophilus [dur″m -tof′ľ-l s] a genus of bacteria in the family Dermatophilaceae. Broad, gram-positive, filaments that fracture longitudinally and transversely, producing coccoid cells and flagellated, motile zoospores.

  • D. chelonae causes skin lesions in turtles.
  • D. congolensis causes mycotic dermatitis, strawberry footrot, streptothricosis, rain scald. Previously classified as Dermatophylus congolense, Actinomyces dermatonomus, Tetragenus congolensis, Actinomyces congolensis, Nocardia dermatonomous, Streptothrix bovis, Dermatophilus dermatonomus and Dermatophilus pedis.

• dermatophyte [dur′m -to-fīt″] superficial fungal skin infection caused by a dermatophyte; in animals the most common pathogens are Microsporum, Nannizzia or Trichophyton spp.

  • d. test medium (DTM) selective enriched fungal culture growth medium for dermatophytes that contains phenol red as color indicator. The color indicator helps identify fungal colonies needing microscopic examination; color change alone is NOT diagnostic of a dermatophyte pathogen.

• dermatophytosis [dur″m -to-fi-to′sis] 1. an infection of the superficial layers of the skin and the hair fibers with one of a group of dermatophytic fungi. Some of the fungi are obligate parasites of animals, others have the same relationship with humans, and some are free-living in the soil and only invade animal skins in unusual circumstances. The common species are Trichophyton verrucosum in cattle, T. equinum in horses; in dogs and cats the infections are Microsporum canis, Nannizzia gypsea (M. gypseum) and T. mentagrophytes. In sheep and goats the infection is usually T. verrucosum and in pigs Nannizzia nana (M. nanum). 2. The infection is very superficial and does almost no injury to animals, but efforts are usually made to prevent its spread because it is highly infectious, including for humans. In companion animals this zoonotic aspect is very important in management of cases. Called also ringworm. See also club lamb fungus.

  • honeycomb r. see favus.
  • sylvatic d. dermatophytosis in domestic animals transmitted from wild animals.

• dermatoplasty [dur′m -to-plas″te] the use of skin grafts in plastic surgery to correct defects caused by injury or disease.

• dermatorrhagie parasitaire [Fr.] parafilariasis.

• dermatosclerosis [dur″m -to-skl -ro′sis] see scleroderma.

• dermatosis [dur″m -to′sis] pl dermatoses; any disease of the skin, but generally refers to those that are non-inflammatory. See also dermatitis.

  • ear margin d. a disorder of keratinization in which greasy plugs form on the hair at the edges of the external ear flap in dogs, mainly Dachshunds. Ulceration, fissures, necrosis, and scarring may follow.
  • exfoliative d. one involving severe desquamation; includes drug reaction, contact hypersensitivity, autoimmune diseases, cutaneous lymphomas, and parapsoriasis.
  • generic dog food d. see generic petfood.
  • growth hormone-responsive d. see alopecia X.
  • hereditary lupoid d. a scaling and crusting skin disease seen from a young age in German shorthaired pointers.
  • infantile pustular d. pustules, depression and anorexia in neonatal puppies; the etiology is unknown.
  • invisible d. skin diseases that are evident clinically, but the histopathology is consistent with normal skin.

    D-22.

    

    (A) Dermatophytosis (ringworm) lesions in a horse. (B) Dermatophytosis (ringworm) in calves caused by Trichophyton verrucosum. (C) Dermatophytosis (ringworm) in a pig caused by Trichophyton spp. (D) Dermatophytosis (ringworm) lesions in a dog caused by Microsporum canis.

  • linear IgA d. a rare, immune-mediated skin disease of Dachshunds in which immunoglobulin A is deposited at the basement membrane zone. There are pustules, with alopecia, hyperpigmentation, scaling, and crusting.
  • linear preputial d. a narrow band of erythema or hyperpigmented skin on the prepuce that sometimes occurs in male dogs with hyperestrogenism; most often associated with an estrogen-secreting testicular tumor, as a Sertoli cell tumor.
  • psychogenic d. see psychogenic alopecia.

    D-23.

    

    Zinc-responsive dermatosis in a Siberian husky.

  • seborrheic d. see seborrheic dermatitis.
  • sterile neutrophilic d. cutaneous and extracutaneous sterile infiltrates of neutrophils with systemic signs of fever, arthritis, pneumonia, and marked neutrophilia with many similarities to Sweet’s syndrome in humans. A rare occurrence in dogs and horses; some cases have had a temporal association with administration of carprofen.
  • subcorneal pustular d. a rare skin disease of dogs in which short-lived, sterile, superficial pustules form, particularly on the head and trunk. Pruritus is variable. The cause is unknown; Miniature schnauzers may be predisposed.
  • d. vegetans an inherited skin disease of Landrace pigs. Young piglets may be affected at birth or develop at an early age an erythematous, papular dermatitis, mainly on the ventral abdomen and medial thighs. There is also erythema and edema of the coronary bands and subsequent deformities of the foot. Pneumonia develops before death.
  • vitamin A-responsive d. some skin disorders, not caused by vitamin A deficiency, may respond to supplementation with vitamin A or retinoids. See seborrheic dermatitis, sebaceous adenitis.
  • zinc-responsive d. a breed-related form occurs in Siberian huskies, Alaskan malamutes and Bull terriers, resulting from defective intestinal absorption of zinc; a dermatosis can occur in puppies of any breed if their diet is deficient in zinc or absorption is impaired by excessive supplementation of calcium. There is scaling and crusting, especially over pressure points and footpads. See also parakeratosis for a similar disease in pigs and a familial one in cattle.

• dermatosparaxis [dur″m -to-sp -rak′sis] an inherited defect in collagen synthesis caused by a deficiency of procollagen peptidase. Results in fragility, hyperelasticity, and laxity of the skin. Occurs in cattle, some breeds of sheep, and Himalayan cats. Called also Ehlers–Danlos syndrome, hyperelastosis cutis, cutaneous asthenia, hereditary equine regional dermal asthenia (HERDA).

• dermatotherapy [dur″m -to-ther′ -pe] treatment of skin diseases.

• dermatotropic [dur″m -to-tro′pik] having a specific affinity for the skin.

  • d. bovine herpesvirus see lumpy skin disease.

• Dermatoxys a genus of nematodes in the family Oxyuridae. Includes Dermatoxys veligera (occurs in the large intestine of rabbits and hares).

• dermatozoon [dur″m -to-zo′ n] any animal parasite on the skin; an ectoparasite.

• Dermestes a genus of larder beetles in the order Coleoptera.

• dermis [dur′mis] the corium; the principal layer of skin between the epidermis and the subcutaneous tissue; made up mostly of a network of collagen fibers but also containing nerves, blood vessels, cells, and other fibers. It is divided into papillary and reticular parts, and when tanned forms leather.

  • hoof d. a greatly modified dermis, continuous at the coronet with the common dermis of the skin; the modified dermis supports the horn of the hoof. See hoof corium.

• dermoblast [dur′mo-blast] the part of the mesoderm that develops into the true skin.

• dermobrasion dermabrasion.

• Dermocystidium a protozoan parasite that causes cysts in the skin of fish and amphibians.

  • D. ranae parasitizes the grass frog (Rana temporaria).

• dermoepidermal [dur″mo-ep-ľ-dur′m l] pertaining to the dermis and the epidermis.

  D-24.

  

  Dermoid in a dog, extending from the temporal aspect of the cornea into the bulbar conjunctive. Hairs can be seen emanating from the surface. Johnston, S.A., Tobias, K. Veterinary Surgery: Small Animal Expert Consult: 2-Volume Set, 2nd ed. Saunders, 2017.

  • d. junction is straight compared to the undulating border in humans; consists of lamina lucida externa, lamina densa, lamina lucida interna, and anchoring filaments.

• Dermoglyphus a genus of the mite family Dermoglyphidae. Includes D. elongatus and D. minor (found in the feather shafts of birds but cause no lesions).

• dermographia see dermatographism.

• dermographism [dur″mo-graf′iz- m] see dermatographism.

• dermoid [dur′moid] 1. skinlike. 2. a dermoid cyst.

  • d. cyst a tumor of developmental origin consisting of a fibrous wall lined with stratified epithelium and containing hair follicles, sweat glands, sebaceous glands, nerve elements, and teeth; a teratoma. Occurs in subcutaneous sites, in the ovary and various locations in the eye, including cornea, conjunctiva, and eyelids.
  • ocular d. dermoid on the eyelid, cornea or conjunctiva.
  • ovarian d. when these cysts occur in the ovary they may present no signs but their long pedicles may cause twisting, resulting in acute abdominal pain.
  • d. sinus an inherited abnormality in Rhodesian Ridgeback dogs in which an embryonic invagination of the skin, residual from closure of the neural tube in the embryo, persists and connects the skin with the dura mater in the vertebral canal or to an intervening structure. Characterized by the presence of a tuft of hair protruding from each sinus and sometimes complicated by infection with drainage. Called also pilonidal sinus.

• dermoidectomy [dur″moid-ek′t -me] excision of a dermoid cyst.

• dermomycosis [dur″mo-mi-ko′sis] dermatomycosis.

• dermonecrosis [dur″mo-n -kro′sis] necrosis of the skin.

• dermopathy [d r-mop′ -the] any skin disease; dermatopathy.

• dermoscopy a noninvasive point-of-care diagnostic tool that provides illuminated magnified viewing of the surface of the skin; used particularly for hair and follicular diseases, including dermatophytosis (ringworm).

• dermosynovitis [dur′mo-sin″o-vi′tis] inflammation of the skin overlying an inflamed bursa or tendon sheath.

• dermotropic [dur″mo-tro′pik] attracted to, localizing in, or entering the skin.

• dermovascular [dur″mo-vas′ku-l r] pertaining to the skin and blood vessels of the skin.

• derodidymus [der″o-did′ -m s] dicephalus.

• deroof [de-rōōf′] to remove a portion of tissue surrounding an enclosed lesion permanently exposing the cavity that is left to heal by second intention. Used most commonly in the treatment of rectal fistulae and tunnel-type skin grafts.

• derquantel 2-desoxyparaherquamide; a spiroindole; a medium spectrum anthelmintic used against nematodes in ruminants.

• dermolipoma [dur″mo-lľ-po′m ] a congenital, yellow growth of fatty tissue occurring under the bulbar conjunctiva.

• derriengue [dar-yāng′ga] from the Spanish derrengado meaning wobbly; an irreversible posterior paresis and paralysis in cattle in the Caribbean region caused by an unidentified toxin in Zamia spp. leaves or seeds; degenerative lesions present in spinal cord white matter, including the proprioceptive pathways. See also zamia staggers. This term also used in South America for paralytic rabies and bovine and equine encephalomyelitis.

  D-25.

  

  Descemetocele. From Maggs, D. Slatter’s Fundamentals of Veterinary Ophthalmology, 4th ed. Saunders, 2008.

• derris [der′is] powdered root of plants of the genus Derris of the family Leguminosae. Used as an insecticide. See also rotenone.

• Derry’s disease type 2, GM₁ gangliosidosis.

• Derzsy’s disease see goose hepatitis.

• DES diethylstilbestrol.

• desaturase [de-sach′ -rās] an enzyme capable of catalyzing desaturation of fatty acids, i.e the introduction of a carbon-carbon double bond into a saturated fatty acyl chain.

• desaturation [de-sach″ -ra′sh n] insertion of double bonds; process of insertion of double bonds in the hydrocarbon chain of fatty acids.

• descemetocele [des″ -met′o-sēl] deep corneal ulcer with complete stromal loss such that Descemet’s membrane is exposed; usually a result of bacterial superinfection of a simple corneal ulcer.

• Descemet’s membrane [des- -ma′] the posterior lining membrane of the cornea, a thin hyaline membrane between the substantia propria and the endothelial layer. In buphthalmos, stretching of the globe may be accompanied by tears in Descemet’s membrane, called Descemet’s streaks.

• descensus [de-sen′s s] pl. descensus [L.] downward displacement or prolapse.

  • d. testis normal migration of the testis from its fetal position in the abdominal cavity to its location within the scrotum.
  • d. uteri prolapse of the uterus.

• descenting [de-sen′ting] surgical excision of the sebaceous glands on the top of the head of the male goat, or the anal scent glands of the ferret, skunk or other mustelid, in order to eliminate the unpleasant odors each gives off. Descenting of pets is banned in some countries.

• Deschamps aneurysm needle [da-shah′] a long thin instrument with a palm-held handle and a thin needle-like extension that at its tip bends laterally at right angles and then describes a semicircle in the same plane. The tip has a needle eye and a pointed but not sharp end. It is designed to place ligatures around vessels in poorly accessible sites.

• descriptive statistics see statistics.

• Descurainia pinnata a plant member of the Brassicaceae family, a mustard; an unidentified toxin causes impaired vision, inability to swallow, paresis of tongue and muscles of mastication. Called also tansy mustard.

• desensitization [de-sen″sľ-tľ-za′sh n] the prevention or reduction of immediate hypersensitivity reactions mediated by IgE by the administration of graded doses of allergen; hyposensitization. See also immunotherapy.

  • extinction d. see extinction.

• desensitize [de-sen′sľ-tīz] 1. to deprive of sensation. 2. to subject to desensitization.

• desert baileya (d. marigold) Baileya multiradiata.

• desert fever the primary form of coccidioidomycosis. Called also desert rheumatism.

• desert poison bush Gastrolobiumgrandiflorum.

• desert rheumatism see desert fever.

  D-26.

  

  Desmarres forceps.

• desex removal of reproductive organs, the ovaries or testes.

• desferrioxamine [des-fer″e-oks′ -mēn] see deferoxamine.

• desflurane [des-floo′rān] a highly volatile, fluorinated inhalant anesthetic agent with low blood/gas solubility.

• desiccant [des′ľ-k nt] 1. promoting dryness. 2. an agent that promotes dryness.

• desiccate [des′ľ-kāt] to render thoroughly dry.

• desiccation [des″ľ-ka′sh n] the act of drying.

• designated persons (DPs) staff in a radiology unit who are in frequent contact with x-rays and who are monitored for radiation exposure and are allotted a higher Dose Equivalent Limit of radiation than other persons. It is expected that the DPs will have been instructed in all matters related to radiation safety.

• designer dogs crossbred dogs with hybrid names; generally with purebred parents of two different breeds. The possibilities are endless; sometimes there is an objective: to dilute any undesirable heritable traits of one breed, such as hip dysplasia, or to gain favorable heritable traits, such as a good temperament or being hypoallergenic for owners, a claim made for poodles, but with little evidence. Some of the “oodle” dogs are Labradoodle, Cavoodle, Cockpoo, Schnoodle. Genetic testing is available to certify that the parents were purebreds.

• desipramine [d -sip′r -mēn] a tricyclic antidepressant.

• deslanoside [des-lan′o-sīd] a rapid-acting cardiotonic glycoside obtained from lanatoside C.

• deslorelin a GnRH analog used as an implant or long-acting injection for induction and timing of ovulation in mares and some other species. Also used as a superagonist for contraceptive purposes.

• Desmarres pertaining to Louis-Auguste Desmarres, French ophthalmologist (1810–1882).

  • D. chalazion forceps forceps for grasping and isolating the eyelid surrounding a chalazion. Thumb-operated spring forceps with large oval tips to the blades, one a solid plate the other a circle. The blades can be clamped shut with a thumbscrew to provide hemostasis and stabilization of the tissue.
  • D. retractors handheld eyelid retractors consisting of a handle and a bent spoon tip which curves back on itself.

• desm(o)- word element. [Gr.] ligament.

• desmin [dez′min] protein found in muscle cells that forms intermediate filaments.

• desmitis [des-mi′tis] inflammation of a ligament.

• desmocollins [dez″mo-kol′inz] cadherin-like adhesion molecules found in the core of desmosomes; responsible for adhesive recognition between cells, and they serve crucial functions in the maintenance of tissue integrity in epithelia and cardiac muscle.

• desmocranium [des″mo-kra′ne- m] the mass of mesoderm at the cranial end of the notochord in the early embryo, forming the earliest stage of the skull.

• Desmodus rotundus murinus [dez-mo′d s] vampire bat of Central and South America. Important as long-term vectors of rabies virus. See also derriengue.

• desmogleins [dez-mog′le-inz] one of the glycoproteins found in the core of desmosomes; responsible for adhesive recognition between cells. In the autoimmune skin diseases, pemphigus foliaceus and pemphigus vulgars, autoantibodies are formed against desmoglein 1 (Dsg1), expressed predominantly in the upper layers of the epidermis, and desmoglein 3 (Dsg3), involved in the adhesion of basal cells of the epidermis and mucosae.

• desmography [des-mog′r -fe] a description of ligaments.

• desmoid [dez′moid] 1. fibrous or fibroid. 2. a fibromatous tumor arising in a muscle sheath; it resembles a fibrosarcoma. Called also desmoid, desmoma.

• desmology [des-mol′ -je] the science of ligaments.

• desmolysis [des-mo-li′sis] acantholysis.

• desmoma [dez-mo′m ] see desmoid (2).

• desmopathy [des-mop′ -the] any disease of the ligaments.

• desmoplasia [des″mo-pla′zh ] the formation and development of fibrous tissue, usually indicating that caused by neoplastic processes.

• desmopressin [des″mo-pres′in] a synthetic analog of 8-arginine vasopressin; the acetate (DDAVP) is used for antidiuretic hormone replacement therapy in the management of central diabetes insipidus; to control bleeding in von Willebrand’s disease in dogs; and for the temporary polyuria and polydipsia associated with trauma to or surgery in the pituitary region.

  • d. response test assesses renal responsiveness to antidiuretic hormone by administering desmopressin and measuring the effect on 24-hour water intake and urine concentration. A normal response is a reduction of at least 50% with urine specific gravity of 1.020 or greater.

• desmorrhexis [des″mo-rek′sis] rupture of a ligament.

  • prepubic d. rupture of the prepubic ligament.

• desmosine [des′mo-sēn] special amino acid, derived from four lysine residues, and found only in elastin. Allows elastin to stretch reversibly in all directions.

• desmosome [dez′mo-sōm] the ‘spot-welds’ that provide one of the structural units that bind epithelial cells together.

  • d. core a dense core of glycoproteins filling the space between cells which are adhered by desmosomes.
  • half d’s structures that provide points of adhesion to anchor cytoskeletal elements to basal cell membranes. Called also hemidesmosomes.

• desmotomy [des-mot′o-me] the cutting or division of ligaments. See also patellar ligament desmotomy, check ligament desmotomy.

• desnooding surgical removal of the snood in the turkey to prevent cannibalism and the creation of a portal of entry for erysipelas infection.

• desonide [des′ -nīd] a synthetic corticosteroid used as a topical antiinflammatory agent in the treatment of steroid-responsive dermatoses.

• desorb [de-sorb′] to remove a substance from the state of absorption or adsorption.

• desorption [de-sorp′sh n] the process or state of being desorbed.

• desoximetasone [des-ok″sľ-met′ -sōn] an anti-inflammatory, antipruritic and vasoconstrictive corticosteroid used topically to relieve inflammation in corticosteroid-responsive dermatoses. Called also deoxydexamethasone, desoxymethasone.

• desoxy- prefix fordeoxy- desoxy- denoting removal of an oxygen atom from a molecule; a reduced amount of oxygen. See also words beginning deoxy-.

• 11-desoxycorticosterone, deoxycorticosterone, deoxycortone [desok″ se-kor″tľ-kos′t r-ōn] one of the mineralocorticoids, adrenocortical steroids that lack a substituent at C-11; has a greater effect on electrolyte metabolism than glucocorticoids. Available pharmaceutically as the acetate (DOCA), which is short-acting, and the pivalate (DOCP), a slow release form for use in the treatment of hypoadrenocorticism.

• desoxymethasone [des-ok″se-meth′ -sōn] desoximetasone.

• desquamation [des″kw -ma′sh n] shedding of epithelial cells as individual scales or in larger sheets of adherent cells.

• desulfhydrase [de″s lf-hi′drās] an enzyme that splits cysteine into hydrogen sulfide, ammonia and pyruvic acid.

• detachment [de-tach′m nt] the condition of being separated or disconnected.

  • exudative d. retinal detachment due to efflux usually from the choroid of a serous transudate, hemorrhage, or inflammatory fluid from the choroid that accumulates between the retinal pigment epithelium and neurosensory retina, e.g., systemic hypertension, chorioretinitis.
  • retinal d. separation of the nine inner layers of the neurosensory retina from the retinal pigment epithelium, which typically remains attached to the underlying choroid; therefore sometimes called retinal separation. Retinal detachment occurs due to one of three mechanisms: rhegmatogenous, tractional or exudative. Causes include inherited retinal dysplasia, systemic hypertension, chorioretinitis, hyperviscosity, immune-mediated disease, vasculitis, or following lens removal.
  • rhegmatogenous d. retinal detachment due to tearing the retina, and creation of breaks through which the vitreous can pass and undermine the retina.
  • tractional d. retinal detachment due to contraction of fibrinous or hemorrhagic debris within the vitreous that create traction bands pulling the neurosensory retina centripetally.

• detail in radiological terms means ease of defining structures visually. Depends on degree of contrast, sharpness of edges and absence of fogging or other obscuring defect.

• detection limit [de-tek′sh n] the lowest concentration of an analyte that can be detected with reasonable certainty for a given analytical range.

• detemir see detemir insulin.

• detergent [de-tur′j nt] 1. purifying, cleansing. 2. an agent that purifies or cleanses.

  • anionic d. a substance that when dissolved contributes a hydrophobic ion that carries a negative charge to the solution. Soap is an example.
  • cationic d. the dissociated substance produces a positively charged hydrophobic ion. The quarternary ammonium compounds are the best known examples. They are innocuous if properly diluted but the concentrates can be toxic.
  • nonionic surface-acting d. e.g., the polyoxyethylenes, are regarded as nonpoisonous.

• detergescence the state of relative dehydration that contributes greatly to the transparency of the cornea; maintained by several active mechanisms, especially the sodium-pump of endothelium and epithelium.

• determinant [de-tur′mľ-n nt] a factor that establishes or changes the nature of an entity or event. The factor may be environmental, be a part of the host or its defenses, be single or multiple and be immediate or remote.

  • allotypic d. an antigenic determinant that varies among members of the same species.
  • antigenic d. an exposed region of an antigen against which immune responses are made and that represent the precise site that is bound by antibody or the T cell receptor; an antigen such as a protein has many antigenic determinants. Called also epitope.
  • disease d’s factors that affect the occurrence or rate of occurrence of a disease.
  • hidden d. an antigenic determinant located in an unexposed region of a molecule so that it is prevented from interacting with receptors on lymphocytes, or with antibody molecules, and is unable to induce an immune response; it may appear following alteration of molecular secondary or tertiary structure.
  • isotypic d. one that occurs in all individuals of the same species.
  • key d. a risk factor that is key to the occurrence of a disease and that is the subject for modification or elimination to prevent or correct the disease.

• determination [de-tur′mľ-na′sh n] the establishment of the exact nature of an entity or event. See also age determination, sex determination.

  • d. coefficient see determination coefficient.
  • embryonic d. the loss of pluripotentiality in any embryonic part and its start on the way to an unalterable fate.

• determinism [de-tur′mľ-niz- m] the theory that all phenomena are the result of antecedent conditions and that nothing occurs by chance.

• deterministic effect in radiation protection, effects that occur once a threshold exposure has been exceeded. Examples include skin erythema and cataract formation.

• deterministic model one in which each variable changes according to a mathematical formula, rather than with a random component.

• detomidine [de-to′mľ-dēn] a potent α₂-adrenoceptor agonist, used as a sedative and analgesic, primarily in horses.

• detorsion rod [de-tor′sh n] an obstetrical instrument used to assist in the correction of uterine torsion in the cow. It is a meter-long rod with a bar handle for applying torque. At the other end is a double prong with an eyelet at the end of each prong. Each of the two presenting limbs is fixed to one of the prongs by rope or chain, and the fetus can then be rotated along its long axis by rotating the handle.

• detoxicate [de-tok′sľ-kāt] detoxify.

• detoxification, detoxication [de-tok″sľ-fľ-ka′sh n, de-tok″sľ-ka′sh n] 1. reduction of the toxic properties of a substance. 2. treatment designed to assist in recovery from the toxic effects of a drug.

  • metabolic d. reduction of the toxic properties of a substance by chemical changes induced in the body, producing a compound that is less poisonous or more readily eliminated.

• detoxify [de-tok′sľ-fi] to subject to detoxification.

• detrition [de-trish′ n] the wearing away, as of teeth, by friction. See also attrition.

• detritus [de-tri′t s] particulate matter produced by or remaining after the wearing away or disintegration of a substance or tissue. See also debris.

  • d. cysts occur in arthritis where there is hemorrhage and necrotic bone.

• detrusor [de-troo′s r] a general term for a muscle that expresses a substance. The detrusor muscle of the bladder squeezes urine toward the outlet.

• detumescence [de″too-mes′ ns] the subsidence of congestion and swelling.

• detusking removal of part or all of the tusks of a boar to prevent injury to other pigs and people.

• deuterium (D or ²H) [doo-tēr′e- m] the mass 2 isotope of hydrogen; it is available as a gas or heavy water and is used as a tracer or indicator in studying metabolism.

• deuterohemophilia [doo″t r-o-he-mo-fil′e-] a group of hemorrhagic disorders resembling classical hemophilia, due to coagulation factor deficiencies or to the action of certain anticoagulants.

• Deuteromycetes [doo″t r-o-mi-se′tēz] a group of fungi for which the sexual form is not known (Fungi Imperfecti) and that contains many of the fungi pathogenic for humans and animals.

• Deuteromycota [doo″t r-o-mi-ko′t] the Fungi Imperfecti, so called because their true taxonomic position cannot be defined because their sexual state has not been observed.

• deuteropathy [doo″t r-op′ -the] a disease that is secondary to another disease.

• deuteroporphyrin III the protoporphyrin of heme, the only known naturally occurring isomer of etioporphyrin III.

• Deutscher wachtelhund a medium-sized, muscular gundog with a thick, long wavy haircoat of brown or brown schimmel (brown ticked with white). It is not well known outside Germany. Called also German spaniel.

• devascularization [de-vas″ku-l r-ľ-za′sh n] interruption of circulation of blood to a part due to obstruction or destruction of blood vessels supplying it.

• developer in film-screen radiology the reducing agent that converts the latent image to a visible image on the exposed x-ray film; changes exposed silver halide crystals to black metallic silver.

• developing agent [de-vel′ p-ing] see developer.

• development [de-vel′ p-m nt] the process of growth and differentiation.

• developmental [de-vel″ p-men′t l] pertaining to development.

  • d. anomaly absence, deformity or excess of body parts as the result of faulty development of the embryo. Called also developmental defect.
  • d. defect see developmental anomaly (above).

• Deverra triradiata a Eurasian desert plant in the family Apiaceae containing furanocoumarins; causes primary photosensitization. Called also Pituranthos triradiatus.

• deviant [de′ve- nt] varying from a determinable standard.

• deviation [de″ve-a′sh n] variation from the regular standard or course. 1. In ophthalmology, a tendency for the visual axes of the eye to fall out of alignment owing to muscular imbalance. 2. in statistics the difference between the predicted value of a variable and the actual value.

  • standard d. (σ) a measure of the dispersal of a random variable; the square root of the average squared deviation from the mean. For data that have a normal distribution about 68% of the data points fall within one standard deviation from the mean, and 95% fall within two standard deviations.

• devil’s pertaining to the devil; said of something evil.

  • d. apple Solanumcapsicoides.
  • d. bit see Scabiosa succisa.
  • d. droppings see Asafetida.
  • d. fig see Solanum torvum.
  • d. food see Datura stramonium.
  • d. grip a conformation defect in sheep in which the thorax is pinched in behind the shoulders. Reputed to make affected sheep more susceptible to fleece rot and blowfly strike.
  • d. ivy see Datura.
  • d. thorn see Tribulus terrestris.
  • d. trumpet see Datura stramonium.

• devitalized literally, without life; usually describes tissues deprived of blood supply or damaged and with little or no prospect of survival.

• devocalization surgical interference with the voice-producing mechanism to prevent annoying noise made by the animal. In the dog and sea lion, the operation is a resection of the vocal cords. Equine devocalization was an important procedure for mounted units in wartime; it was a ventriculectomy with added cord resection for a greater level of muting. In the peacock, devocalization is carried out by scarification of the mucosa of the syrinx. In dogs, a procedure opposed by the American Veterinary Medical Association except as a final alternative to euthanasia and only after behavioral modification has failed to correct the excessive barking.

• Devon a cherry red breed of dairy cattle, bred in the UK. See also South Devon.

• Devon rex see Rex.

• Dewar flask an insulated container for the storage of cryogenic liquids such as liquid nitrogen.

• dewattling surgical removal of the wattles from a chicken. See also decombing.

• dewclaw [doo′klaw] 1. the rudimentary first digit of dogs and cats, found on the inner (medial) side of the front legs, above the weight-bearing digits. These are sometimes removed from puppies at an early age to reduce the risk of injury throughout life. Occasionally found on the hindlegs of some dogs and in some breeds this is required in the breed standard, e.g., the Great Pyrenees dog and Briard, in which double rear dewclaws must be present. 2. the accessory claws of the ruminant foot.

  • d. slough (2) sequel to laminitis, severe edema of the lower extremity, severe coronitis.

• dewlap [doo′lap] loose skin under the throat and neck that may be pendulous in some species or breeds, e.g., Bloodhounds, Indian cattle, rabbits, and some birds.

• deworming preparations [de-w rm′ing] see anthelmintic.

• DEXA dual-energy x-ray absorptiometry, used to measure bone mineral density. See also DXA.

• dexamethasone [dek″s -meth′ -sōn] a synthetic glucocorticoid used primarily as an anti-inflammatory agent in various conditions, including autoimmune diseases, hypersensitivity reactions and shock; it is also used in a screening test for the diagnosis of Cushing’s syndrome, and for the termination of pregnancy in cattle.

  • d. suppression test the determination of blood cortisol concentrations before and after administration of dexamethasone assists in diagnosing Cushing’s syndrome and identifying the cause, depending on the protocol and dose used. Dexamethasone suppresses secretion of corticotrophin-releasing hormone and ACTH in normal animals and therefore the blood concentration of cortisol is decreased. Dogs or cats with functional adrenal neoplasia are more resistant and even high doses of dexamethasone (high-dose dexamethasone suppression test; HDDST) will not suppress cortisol concentrations; animals with pituitary-dependent disease should suppress. Low doses (low-dose dexamethasone suppression test; LDDST) may be used as a screening test for pituitary-dependent and functional adrenal neoplasia Cushing’s syndrome in dogs.

• dexbrompheniramine [deks″brom-f n-ēr′ -mēn] the dextrorotatory isomer of brompheniramine, used as an antihistamine in the form of the maleate salt.

• dexchlorpheniramine [deks″klor-f n-ēr′ -mēn] the dextrorotatory form of chlorpheniramine used as an antihistamine in the form of the maleate salt.

• dexmedetomidine [deks″med- -to′mľ-dēn] a potent α₂-adrenoceptor agonist, containing only the active (dextro-rotary) isomer of medetomidine; used as a sedative and analgesic.

• Dexon [dek′son] trademark for a synthetic multi-filament suture material, polyglycolic acid, a polymer that is completely absorbable and nonirritating.

• dexpanthenol [deks-pan′th -nol] the d-isomer of panthenol, a coenzyme A precursor with cholinergic activity. Used to increase peristalsis in atony and paralysis of the lower intestine and as an antiflatulent; also used topically to stimulate skin healing in various skin diseases.

• dexrazoxane [deks″ra-zok′sān] a cardioprotective agent used in conjunction with chemotherapeutic drugs such as doxorubicin or daunorubicin to decrease their cardiotoxic side effects.

• Dexter a red or black, short-legged breed of cattle used for dairy or beef purposes, produced in Ireland. Called also Dexter-Kerry. They are achondroplastic and the breed has a number of inherited defects, including bulldog calves.

• dexter [deks′t r] [L.] right, on the right side.

• Dexter-Kerry see Dexter.

  D-27.

  

  Dexter beef bull.

• dextran [deks′tr n] a water-soluble complex branched glucan (polysaccharide made up of glucose molecules) produced by the action of Leuconostoc mesenteroides on sucrose; used as a plasma volume extender. Several preparations of dextran are used as anticoagulants.

  • d. 40 low molecular weight; used as an adjuvant in blood transfusion; an anticoagulant.
  • d. 70 high molecular weight, average 70 daltons, used for plasma volume expansion, with osmotic effects similar to albumin. May interfere with platelet function; promotes rouleaux formation and may interfere with crossmatching of blood.
  • iron d. ferric hydroxide, complexed with a low-molecular-weight dextran; used as an injectable iron supplement, particularly in young pigs, to prevent and treat iron deficiency anemia.

• dextranomer [deks-tran′o-m r] small beads of highly hydrophilic dextran polymers used in débridement of secreting wounds, such as venous stasis ulcers; the sterilized beads are poured over secreting wounds to absorb wound exudates and prevent crust formation.

• dextriferron a complex of ferric hydroxide and partially hydrolyzed dextrin used in the treatment of iron-deficiency anemia.

• dextrin [deks′trin] any of a range of glucose polymers of varying sizes formed during the hydrolysis of starch.

  • limit d. a by-product of glycogenolysis.

• dextrin-1,6-glucosidase dextrin 6-glucanohydrolase; an enzyme that catalyzes the hydrolysis of α-1,6-glucan links in dextrins containing short 1,6-linked side chains.

• dextrinose see isomaltose.

• dextrinosis [dek″strľ-no′sis] a condition characterized by accumulation in the tissues of an abnormal polysaccharide.

• dextrinuria [deks″trľ-nu′re- ] presence of dextrin in the urine.

• dextr(o)- word element. [L.] right.

• dextroaorta [dek″stro-a-or′t ] dextropositioned aorta; a congenital anomaly in which the aorta develops from the embryonic right fouth aortic arch with the left-sided ductus arteriosus and pulmonary artery form a vascular ring around the esophagus. A retroesophageal left subclavian is a common, concurrent compressive anomaly.

• dextrocardia [dek″stro-kahr′de- ] location of the heart in the right side of the thorax, the apex pointing to the right. Atria, ventricles, and great arteries are all inverted, but there is persistence of normal atrialventricular and ventricular-arterial connections

  • mirror-image d. location of the heart in the right side of the chest, the atria being transposed and the right ventricle lying anteriorly and to the left of the left ventricle.

• dextromethorphan [dek″stro-m th-or′fan] a synthetic morphine derivative used as an antitussive in the form of the hydrobromide salt.

• dextroposition [dek″stro-p -zish′ n] displacement to the right.

• dextropropoxyphene [dek″stro-pro-pok′s -fēn] see propoxyphene.

• dextrorotatory [dek″stro-ro′t -re] turning the plane of polarization, or rays of light, to the right.

• dextrose [dek′strōs] an old chemical name for d-glucose, an important energy source for all tissues and the sole energy source for the brain in some species such as the sheep. The term dextrose continues to be used to refer to glucose solutions administered intravenously for fluid or nutrient replacement. See also glucose.

• dextrosuria [dek″strōs-u′re- ] glucosuria.

• dextrothyroxine sodium [dek″stro-thi-rok′sin] the dextrorotatory isomer of thyroxine used as an antihyperlipoproteinemic agent in the treatment of hyperlipemia.

• dextroversion [dek″stro-vur′zh n] 1. version to the right, especially movement of the eyes to the right. 2. location of the heart in the right chest, the left ventricle remaining in the normal position on the left, but lying anterior to the right ventricle.

• df degrees of freedom.

• DF-2 see Capnocytophaga.

• DFA test direct fluorescent antibody test.

• DFB acronym for dark, firm, dry meat. Called also dark cutting beef.

• DHA docosahexaenoic acid.

• DHAP dihydroxyacetone phosphate, an intermediate of glycolysis formed as an end product of the aldol cleavage of fructose-1,6-bisphosphate.

• 24,25-DHCC 24,25-dihydroxycholecalciferol; a metabolite in calcium metabolism, formed in the kidney from 25-hydroxycholecalciferol by the activation of a 24-hydroxylase. See also dihydroxycholecalciferol.

• dhfr gene see dhfr gene.

• DHI see dairy herd improvement.

• DHIA Dairy Herd Improvement Association. Most developed countries have a DHIA dedicated to improving the productivity of their dairy cattle. Membership is optional, but fees are low because of heavy government subsidy. In the US, centers are regional and commonly measure/test/record milk production, milk fat, milk protein, Somatic Cell Count (SCC), as well as animal information on birth date, pregnancy, and number of lactations. In addition, there are options for milk testing to determine pregnancy status, to examine nitrogen (N) efficiency as Milk Urea Nitrogen, Johne’s, and Leukosis. See also dairy herd improvement.

• dhurrin [doo′rin] a cyanogenic glycoside in sorghum.

• DFP di-isopropylfluorophosphate. See isoflurophate.

• DHV deer herpesvirus.

• di- word element. [Gr., L.] two, twice.

• 2,6-di-iodo-4-nitrophenol see disophenol.

• dia- word element. [Gr.] through, between, apart, across, completely.

• diabetes [di″ -be′tēz] excessive excretion of urine, characterized by polyuria and polydipsia. See diabetes mellitus and diabetes insipidus.

  • metahypophysial d. diabetes mellitus that occurs as a result of active hyperplasia or tumor of the acidophil cells of the pituitary gland.

• diabetes insipidus [di″ -be′tēz] a metabolic disorder due to injury of the neurohypophyseal system, which results in a deficient quantity of antidiuretic hormone (ADH or vasopressin) being released or produced, resulting in failure of tubular reabsorption of water in the kidney. As a consequence, there is the passage of a large amount of urine having a low specific gravity and increased thirst. It can be acquired through infection, neoplasm, or trauma to the posterior lobe of the pituitary gland or it may be inherited or idiopathic. Called also central diabetes insipidus.

  • dipsogenic d. i. see psychogenic diabetes insipidus (below).
  • nephrogenic d. i. a form of diabetes insipidus resulting from failure of the renal tubules to reabsorb water; there is excessive production of antidiuretic hormone but the tubules fail to respond to it. Can be secondary to other conditions, including pyometra, hyperadrenocorticism, and hypercalcemia.
  • psychogenic d. i. a primary polydipsia resulting from a disorder of thirst control, or as a behavioral problem. The polyuria is secondary to the excessive water intake. Called also dipsogenic diabetes insipidus.

• diabetes mellitus [di″ -be′tēz] a broadly applied term used to denote a complex group of syndromes that have in common a disturbance in the oxidation and utilization of glucose, which is secondary to a malfunction of the beta cells of the pancreas, whose function is the production and release of insulin. Because insulin is involved in the metabolism of carbohydrates, proteins and fats, diabetes is not limited to a disturbance of glucose homeostasis alone. Diabetes mellitus has been recorded in all species but is most commonly seen in older, obese male cats and middle-aged to older, obese, female dogs. A familial predisposition has been observed in some breeds. Two classifications are recognized. In type 1, or insulin-dependent diabetes mellitus (IDDM), there is a deficiency of insulin. This is the form seen in almost all dogs and some cats with diabetes mellitus. Type 2, or non–insulin-dependent diabetes mellitus (NIDDM), is caused by a relative lack of insulin and insulin resistance. This is the form seen in most cats with diabetes mellitus. A diagnosis of diabetes mellitus is usually not made in dogs and cats until the disease is well advanced or complicated by the development of ketoacidosis. Clinical signs include polyuria, polydipsia, and weight loss despite an increased appetite. Persistent fasting hyperglycemia, glucosuria and sometimes ketonuria are present. Dogs may develop cataracts and present with an acute blindness. Cats may show gait abnormalities, hindlimb weakness, and a plantigrade stance due to diabetic neuropathy. With the development of ketoacidosis, there is anorexia, vomiting, and dehydration.

  • complicated d. m. see diabetic ketoacidosis.
  • hyperosmolar d. m. a syndrome of marked hyperglycemia and hyperosmolarity with central nervous signs, resembling diabetic coma.
  • juvenile d. m. develops in the young, typically less than 1 year of age; uncommon in dogs and cats.
  • secondary d. m. insulin resistance and hyperglycemia secondary to another disease, such as pancreatitis, hyperadrenocorticism, or acromegaly; or treatment with drugs, such as glucocorticoids or progesterone.
  • steroid d. m. altered carbohydrate tolerance is induced by glucocorticoids and progestogens. Hyperglycemia and diabetes mellitus can be associated with the administration of such drugs or naturally occurring hyperadrenocorticism.
  • transient d. m. following successful initiation of treatment, some cats regain their ability to maintain euglycemia; may be long or short term.

• diabetic [di″ -bet′ik] pertaining to or characterized by diabetes.

  • d. dermatopathy see necrolytic migratory erythema.

• diabetogenic [di″ -bet″o-jen′ik] producing diabetes.

• diabetogenous [di″ -be-toj′-n s] caused by diabetes.

• diabrotic [di″ -brot′ik] 1. ulcerative; caustic. 2. a corrosive or escharotic substance.

• diacetoxyscirpenol [di-as″ -tok″se-sur′p -nol] non-macrocyclic trichothecene mycotoxin from the fungi Fusarium spp. Causes emesis, voracious appetite, frequent passage of normal feces, and posterior paresis in pigs.

• diacetylmorphine [di″ -se″t l-mor′fēn] heroin.

• diacrisis [di-ak′rľ-sis] 1. diagnosis. 2. a disease characterized by a morbid state of the secretions. 3. a critical discharge or excretion.

• diacritic [di″ -krit′ik] diagnostic; distinguishing.

• sn-1,2-diacylglycerol [di-a″s l-glis′ r-ol] compound consisting of two long-chain fatty acids esterified to glycerol. Second messenger produced from the action of an agonist via G-proteins activating phospholipase C leading to the hydrolysis of phosphatidylinositol 4,5-bisphosphate to sn-1,2-diacylglycerol and inositol 1,4,5-trisphosphate. sn-1,2-Diacylglycerol subsequently activates protein kinase C by greatly increasing the affinity of the enzyme for calcium ions.

• diadochokinesia [di-ad″ -ko-kľ-ne′zh] the function of arresting one motor impulse and substituting one that is diametrically opposite.

• diadromous term used to describe fish that migrate between fresh and marine waters in either direction. This term includes both catadromous or anadromous fish.

• diadromy migration of fish from fresh to sea water or sea water to fresh water

• diagnose [di′ g-nōs] to identify or recognize a disease.

• diagnosis [di″ g-no′sis] a name given to a disease so that each veterinarian means the same syndrome as every other veterinarian. It is then possible to prescribe for and make a prognosis about any one case on the basis of the outcomes in a series of animals with the same diagnosis. A diagnosis may be the name of a disease with a specific etiology, or one that is only a description of the morphological identity of the disease, a pathoanatomical diagnosis, or be a syndrome that is a description of the total clinical presentation, or a single clinical sign.

  • clinical d. diagnosis based on clinical signs and laboratory findings during life.
  • computer assisted d. a computer program identifies the diseases that fit the identified abnormalities best.
  • differential d. the determination of which one of several diseases may be producing the signs observed.
  • etiological d. identifies the specific cause of the disease.
  • pathoanatomical d. diagnosis to the point of identifying the system and organ involved and the nature of the lesion, but short of identifying the cause.
  • physical d. diagnosis based on information obtained by inspection, palpation, percussion, and auscultation.
  • imaging d. a good imaging report does more than report findings. It interprets these findings as a list of differential diagnoses, or if possible up to the point of making a pathoanatomical diagnosis (see above).
  • veterinary d. diagnosis performed by a veterinarian and based on information gleaned from a variety of sources, including (1) findings from a physical examination, (2) interview with the owner or custodian of the animal, (3) veterinary history of the patient and its cohorts, (4) epidemiology, and (5) paraclinical findings as reported by pertinent laboratory tests and radiological studies.
  • zebra d. arriving at an unlikely diagnosis instead of a more common one. “When you hear hoofbeats look for horses before zebras”.

• diagnostic [di″ g-nos′tik] pertaining to or emanating from the making of a diagnosis.

  • d. disciplines the disciplines applied to the making of diagnoses. Includes clinical medicine, surgery, and reproduction and also epidemiology, pathology, microbiology, parasitology, and toxicology.
  • d. hypotheses preliminary list of potential diagnoses.
  • d. kits commercially available tests used in the diagnosis of disease. Most are intended for biochemical estimation or the qualitative detection of antigen or antibody. Many are based on an ELISA.
  • d. laboratory, veterinary d. laboratory present in most countries to provide veterinary laboratory diagnostic services, particularly with respect to regulatory diseases but, in almost all cases, also for laboratory diagnostic support for any animal disease. Most are supported, in part, by state or national funding but most also need to charge a fee for diagnostic services. In the US, accreditation is through the American Association of Veterinary Laboratory Diagnosticians (AAVLD). Regional veterinary diagnostic laboratories are established to serve the needs of farms in their proximity
  • d. plan in problem-oriented diagnosis, the systematic outline of procedures and tests to be undertaken in making a diagnosis.
  • d. points in acupuncture terminology include association points (back Shu points and alarm points, front Mu points).
  • d. test tests likely to provide information that aids in the making of a diagnosis.
  • d. trail a standard procedure for making a clinical and laboratory examination so that nothing is omitted and so that the procedure can be checked or repeated.

• diagnostician [di″ g-nos-tish′ n] an expert in diagnosis.

• diagnostics [di″ g-nos′tiks] the science and practice of diagnosis of disease.

• diagonal gait see diagonal gait.

• diagram [di′ -gram] a visual representation of information that explains the relationship between qualitative data, concepts or variables; may be taken to include charts and graphs.

  • bar d. a method of presenting data in which frequencies are displayed along one axis and categories of the variable along the other, the frequencies being represented by the bar lengths.
  • ladder d. a method of interpreting cardiac arrhythmias by using the electrocardiogram with a diagram drawn from the important points of atrioventricular conduction.
  • Lewis d. a ladder diagram of cardiac impulse formation and conduction.
  • scatter d. a graphic representation of a scatter of two variables.
  • tree d. see decision tree.
  • Venn d. a pictorial representation, usually in the form of two or more overlapping circles, of the extent to which two or more quantities or concepts have comparable or disparate characteristics.

• diakinesis [di′ -kľ-ne′sis] in the first meiotic division, it is the final step in prophase 1 and is characterized by the termination of chromosome condensation, disintegration of the nuclear envelope, and the apparent disappearance of the nucleolus.

• di-allate a thiocarbamate herbicide; chronic poisoning causes anorexia, weight loss and alopecia. No longer has approval for use in the European Union. See also tri-allate.

• dialysance [di-al′ -s ns] the minute rate of net exchange of solute molecules passing through a membrane in dialysis.

• dialysate [di-al′ -sāt] the material passing through the membrane in dialysis. In peritoneal dialysis, the fluid infused and later removed from the peritoneal cavity.

• dialysis [di-al′ -sis] the diffusion of solute molecules through a semipermeable membrane, passing from the side of higher concentration to that of the lower; a method sometimes used in cases of defective renal function to remove from the blood elements that are normally excreted in the urine (hemodialysis). The principles of dialysis are utilized in renal dialysis with a hemodialyzer (hemodialysis) and in peritoneal dialysis.

  • extracorporeal d. dialysis by a hemodialyzer. See hemodialysis.
  • peritoneal d. dialysis through the peritoneum, the dialyzing solution being introduced into and removed from the peritoneal cavity, as either a continuous or an intermittent procedure. See also peritoneal dialysis.

• dialyzer [di′ -līz″ r] an apparatus for performing dialysis; a hemodialyzer.

  • diameter [di-am′ -t r] the length of a straight line passing through the center of a circle and connecting opposite points on its circumference; hence the distance between the two specified opposite points on the periphery of a structure such as the cranium or pelvis.
  • cranial d’s, craniometric d’s imaginary lines connecting points on opposite surfaces of the cranium.
  • pelvic d. any of the diameters of the pelvis; any measurement that expresses the diameter of the birth canal in the female.

• diamfenetide, diamphenethide a fasciolicide used in sheep; effective against immature flukes but with diminishing activity as the fluke ages. An effective compound for use in prophylactic programs against Fasciola hepatica.

• diamide [di-am′īd] compound containing two amido groups.

• diamidine [di-am′ľ-dēn] 1. a compound that contains two-C (=NH)NH₂ groups (eg pentamidine). 2. a group of antiprotozoal drugs; includes phenamidine, pentamidine, diminazene, and imidocarb.

• diaminobutyric acid a neurotoxin in Lathyrus spp.

• diaminodiphenoxyalkane a schistosomicidal drug (effective in the treatment of schistosomiasis); however, it causes degeneration of pigmented retinal epithelium.

• di-allylacetamide a weedkiller. Acute poisoning is unlikely because of the large dose required. Chronic toxicity is possible.

• diaminophenylsulfone see dapsone.

• diaminopyrimidines synthetic antimicrobial agents that act as competitive antagonists in the conversion of folic acid to folinic acid. Examples are trimethoprim and pyrimethamine. Usually combined with a sulfonamide, providing sequential blockade in nucleic acid synthesis.

• diamnionic [di″am-ne-on′ik] having or developing within separate amniotic cavities, as diamnionic twins.

• diamniotic [di-am″ne-ot′ik] diamnionic.

• Diamond eye cat see Khaomanee.

• diamond skin disease [di′ -mond] see erysipelas (1).

• Diamond’s medium [di′ -mond] a culture medium especially suitable for culturing cervicovaginal mucus for the isolation of Tritrichomonas foetus.

• diamorphine [di″ -mor′fēn] heroin.

• diamphenethide diamfenetide.

• dianthrone group of primary photosensitizing plant pigment toxins, includes hypericin, fagopyrin. Called also helianthrone.

• diapause [di′ -pawz] a state of inactivity and arrested development accompanied by greatly reduced metabolism, as in many eggs, insect pupae and plant seeds. It is a mechanism for surviving adverse weather conditions.

  • embryonic d. state of dormancy used as reproductive strategy in some mammals to extend gestation period, to time birth with favorable environmental or metabolic conditions.

• diapedesis [di″ -p -de′sis] the outward passage of blood cells through intact vessel walls.

• diaphanoscope [de-af′ -no-skōp″] an instrument for transilluminating the interior of a body cavity to allow it to be visible from the exterior.

• diaphemetric [di-af′ -met′rik] pertaining to measurement of tactile sensibility.

• diaphoresis [di″ -f -re′sis] perspiration, especially profuse perspiration.

• diaphoretic [di″ -fo-ret′ik] 1. pertaining to, characterized by, or promoting diaphoresis. 2. an agent that promotes diaphoresis.

• diaphragm [di′ -fram] 1. the musculomembranous partition separating the thoracic and abdominal cavities. On its sides, it is attached to the caudal ribs; ventrally to the sternum; at the back, to the spine. The esophagus, the aorta and vena cava, and nerves pass through the diaphragm. When relaxed, the diaphragm is convex but it flattens and moves caudally as it contracts during inhalation, thereby enlarging the chest cavity and allowing for expansion of the lungs. See also respiration. 2. any separating membrane or structure. 3. a disk with one or more openings or with an adjustable opening, mounted in relation to a lens, by which part of the light may be excluded from the area. See also diaphragmatic.

  • grid d. a grid interposed between the film and the x-ray beam. See also grid (1).
  • Potter–Bucky d. see Potter–Bucky grid.
  • light beam d. an adjustable diaphragm, consisting of two pairs of lead shutters, which is used to restrict a light beam that indicates the dimensions of an x-ray beam and marks the position of the central ray.
  • pelvic d. the muscular sheet guarding the pelvic outlet made up of the coccygeus and levator ani muscles. See Table 12.2.
  • slit d. see filtration membrane.
  • urogenital d. the musculomembranous layer superficial to the pelvic diaphragm, extending between the ischiopubic rami and surrounding the urogenital ducts.

• diaphragma sellae [di″ -frag′m] a sheet of dura separating the pituitary gland in its fossa from the brain above.

• diaphragmatic [di″ -frag-mat′ik] pertaining to the diaphragm.

  • d. abscess in the cow produces a syndrome of humped back, pain on percussion over the xiphoid area, fever, and leukocytosis.
  • d. hernia in cattle, cases resulting from traumatic reticulitis show chronic ruminal tympany, distention, emaciation, anterior displacement of the heart with systolic murmur. Congenital cases in calves and those in cows due to trauma show dyspnea, displacement of the heart, and gut sounds audible in the chest. Horse cases are usually traumatic in origin and result in an acute onset of severe colic with no good distinguishing signs. In dogs and cats, uncommonly congenital but a common sequela to trauma with signs of dyspnea and pleural effusion. See also peritoneopericardial hernia.
  • d. rupture see diaphragmatic hernia (above).
  • d. septal defects include pleuroperitoneal and pericardioperitoneal defects.
  • synchronous d. flutter violent, unilateral hiccoughs occur with each heartbeat, sometimes with muscle tetany reminiscent of lactation tetany; some cases of that disease also have flutter. Acid–base imbalance is present in most cases. Observed in horses immediately after endurance racing and associated with electrolyte abnormalities. Recovery is spontaneous and following treatment with calcium solutions.
  • d. tendon the heart-shaped tendinous center of the diaphragm.

• diaphragmatocele [di″ -frag-mat′o-sēl] see diaphragmatic hernia.

• diaphragmitis [de″ -frag-mi′tis] inflammation of the diaphragm.

  D-28.

  

  Diaphragmatic hernia at post mortem showing intestines and omentum in the thoracic cavity displacing liver and stomach caudally.

• diaphyseal, diaphysial [di″ -fiz′e-l, di″-fiz′e- l] pertaining to or affecting the shaft of a long bone (diaphysis).

  • d. aclasis see multiple cartilaginous exostosis, inherited multiple exostosis.

• diaphysectomy [di″ -fiz-ek′t -me] excision of part of a diaphysis.

• diaphysis [di-af′ -sis] pl. diaphyses. 1. the portion of a long bone between the ends or extremities, which are usually articular, and wider than the shaft; it consists of a tube of compact bone, enclosing the medullary cavity. Called also shaft. 2. the portion of a bone formed from a primary center of ossification.

• diaplasis the setting of a fracture or reduction of a dislocation.

• diapophysis [di″ -pof′ -sis] a transverse process of a vertebra.

• Diaporthe toxica a toxic fungus growing on dead lupin plants (lupin stubble) and in lupin seeds producing phomopsins and causing the toxicosis, lupinosis. See also lupinosis. Phomopsin production was previously, erroneously, attributed to D. woodii (Phomopsis leptostromiformis).

• diapositive mask a mask used in subtraction radiography. It is prepared from a scout film of the site and masks the high density shadows so that the shadow created by a contrast radiograph will be highlighted.

• Diaptomus gracilis [di-ap′to-m s] a diaptomid copepod, a first intermediate host of the cestode Diphyllobothrium latum.

• diapyesis [di″ -pi-e′sis] suppuration.

• diarrhea [di″ -re′] rapid movement of fecal matter through the intestine resulting in poor absorption of water, nutritive elements and electrolytes, and producing abnormally frequent evacuation of watery droppings. The major causes are local irritation of the intestinal mucosa by infectious or chemical agents (gastroenteritis). In all types of diarrhea, there is rapid evacuation of water and electrolytes resulting in a loss of these essential substances. Base (bicarbonate) especially is depleted by diarrhea, thus producing acidosis as well as fluid volume deficit.

  • acute hemorrhagic d. syndrome (AHDS) an acute syndrome in dogs of vomiting and bloody diarrhea with dehydration and marked hemoconcentration. If not treated vigorously, it may lead to circulatory failure and death in a short time. The cause is unknown; Clostridium perfringens enterotoxin has been suspected. Formerly called hemorrhagic gastroenteritis (HGE).
  • acute idiopathic d. acute diarrhea syndromes in horses that are not immediately diagnosable or differentiable and need to be treated symptomatically pending diagnosis, such as salmonellosis, strongylosis, cyathostomiasis, Potomac horse fever, colitis-X, antibiotic-associated diarrhea (below), intestinal clostridiosis.
  • acute undifferentiated d. of the horse see acute idiopathic diarrhea (above).
  • antibiotic-associated d. results from disruption of the normal bowel flora as a result of antimicrobial therapy for any reason. May occur as moderate diarrhea or as a life threatening syndrome often with severe colitis or pseudo-membranous colitis. See also antibiotic-associated colitis.
  • antibiotic-responsive d. chronic diarrhea for which no underlying cause can be found and that is completely responsive to prolonged antibiotic treatment. Commonly affects young large-breed dogs, particularly German shepherds, in which underlying immune dysregulation is suspected. Formerly called small intestinal bacterial overgrowth (SIBO), but no true overgrowth has been demonstrated in dogs. Also called antibiotic-responsive enteropathy.
  • bovine virus d. see bovine virus diarrhea.
  • campylobacter d. watery diarrhea without other obvious signs and without other obvious cause in yearling sheep, calves, and foals. Campylobacter jejuni and C. coli have been suggested as causes. Campylobacter infection is the leading bacterial cause of diarrhea in humans in many industrialized countries and livestock and poultry products are one source. See also winter dysentery.
  • chronic undifferentiated d. of the horse chronic, watery diarrhea for long periods but the horse has normal appetite and loses weight only gradually. Esthetically displeasing to pleasure horse owners. Irreversible but not usually fatal.
  • ciliate d. colitis caused by Troglodytella in primates.
  • dietary d. a result of dietary indiscretion; occurs in all species. It is caused by the chemical or physical nature of the ingested material. The most common occurrence of the syndrome is in newborn animals, especially those who ingest too much milk. There is often a history of access to an oversupply of milk or of a recent change of source to an over-rich milk replacer or indigestible components in replacer. It is also caused by too-rapid drinking. Affected animals are bright and alert and have a normal appetite, but the feces are voluminous, soft to fluid, and evil-smelling. Secondary bacterial enteritis may ensue, but most cases recover spontaneously when the diet is adjusted. Scavenging dogs and cats (‘garbage eaters’) commonly ingest food that is spoiled or to which they are unaccustomed, resulting in various degrees of vomiting or diarrhea. Called also dietetic scours.
  • effusion d. caused by an increase in the transepithelial hydrostatic pressure gradient, such as occurs in congestive heart failure and hepatic portal hypertension.
  • large bowel d. in dogs and cats, signs referable to the site of enteric disease responsible for the diarrhea being the large intestine include tenesmus, mucus, hematochezia, and increased frequency of defecation.
  • malabsorptive d. villous atrophy, such as occurs with some viral infections, causes malabsorption diarrhea because of the reduction in area of absorptive intestinal epithelium.
  • nursery d. see nursery diarrhea.
  • osmotic d. an overload of unabsorbed osmotically active particles will attract and retain water, increasing fecal volume and causing diarrhea. Associated with maldigestion, malabsorption, overeating, excessive carbohydrates or fats. The basis for the laxative effect of magnesium sulfate, sodium sulfate or sodium phosphate.
  • pasture d. see copper nutritional deficiency.
  • porcine epidemic d. occurs in most swine-raising countries in Europe and Asia and also in North America, causes an economically significant outbreak of enteric disease with acute diarrhea, dehydration and significant mortality. Affects pigs of all ages. It is caused by porcine epidemic diarrhea virus, a coronavirus that replicates in differentiated enterocytes covering the villi of the small intestine, leading to villous atrophy and malabsorption. There are several genotypes of the virus. Called also epizootic porcine diarrhea.
  • psychogenic d. see irritable bowel syndrome.
  • secretory d. derangement of normal secretory and absorptive functions of intestinal epithelium such as occurs with bacterial enterotoxins may result in excessive secretion and a resulting diarrhea. Escherichia coli is the prime example of an infection with this effect.
  • small bowel d. in dogs and cats, signs that localize the origin of diarrhea to the small intestine include lack of tenesmus or mucus, increased fecal volume, normal to mild increase in fecal frequency, melena and weight loss.
  • undifferentiated d. of the newborn the situation in which a newborn animal (less than 7 days old) has life-threatening acute diarrhea. There is insufficient time and it would cost too much to differentiate between all of the possible causes. Added to this is the common occurrence in which there are two or more agents present, often acting in concert. Because of the need to treat these cases urgently and effectively if their lives are to be saved, it has become the practice to group them together for the purposes of treatment, mainly with fluid replacement therapy and correction of acid base imbalance.

• diarrheogenic [di″ -re″o-jen′ik] giving rise to diarrhea.

• diarrhoea diarrhea.

• diarthric [di-ahr′thrik] pertaining to or affecting two different joints; biarticular; diarticular.

• diarthrodial [di″ahr-thro′de- l] of the nature of a diarthrosis.

  • d. joint see diarthrosis.

• diarthrosis [di″ahr-thro′sis] pl. diarthroses [Gr.] a specialized form of articulation in which there is more or less free movement, the union of the bony elements being surrounded by an articular capsule enclosing a cavity lined by synovial membrane; an outmoded term for a synovial joint.

  • d. rotatoria a joint characterized by mobility in a rotary direction.

• diarticular [di″ahr-tik′u-l r] pertaining to two joints; diarthric.

• diaschisis [di-as′kľ-sis] loss of function and electrical activity in an area of the brain due to a lesion in a remote area that is neuronally connected with it.

  D-29.

  

  Diascopy.

• diascopy [di-as′k -pe] a technique for examination of erythematous skin lesions. If a clear glass slide, pressed over the lesion, causes the color to fade, there is vascular engorgement; if it does not fade, it is hemorrhage in the skin (ecchymosis).

• diastase [di′ -stās] a combination of enzymes produced during germination of seeds, and contained in malt; it converts starch into maltose and then into dextrose.

• diastasis [di-as′t -sis] 1. separation of two normally attached parts such as the separation of two normally attached bones between which there is no true joint. Also, an abnormally large separation between associated bones, as between the ribs. 2. Part of diastolic filling after the initial rapid inflow of blood into the left ventricle when LV pressures start to approach LA pressures and the speed of inflow slows. It immediately precedes atrial contraction, the final stage of diastolic filling.

• diastema [di″ -ste′m] space between teeth in a jaw creating a visible gap. See also interdental space.

• diastematocrania [di″ -stem″-to-kra′ne-] congenital longitudinal fissure of the cranium.

• diastematomyelia [di″ -stem″-to-mi-e′le-] abnormal congenital lengthwise division of the spinal cord by a bony spicule or fibrous band protruding from a vertebra or two, into two halves, each of the halves being surrounded by a dural sac.

• diastematopyelia [di″ -stem″-to-pi-e′le-] congenital median fissure of the pelvis.

• diastole [di-as′to-le] the phase of the cardiac cycle when the heart fills with blood. See also blood pressure and heart.

• ventricular d. period in which the ventricles dilate and fill with blood between contractions. Cardiac filling occurs initially by a suction effect of the ventricles and subsequently by contraction of the atria forcing blood into the ventricles.

• atrial d. the period during which the two atria are relaxing, dilating, and filling with blood.

• diastrophic [di″ -strof′ik] bent or curved; said of structures, such as bones, deformed in such manner.

• diataxia [di″ -tak′se-] ataxia affecting both sides of the body.

• diathermal, diathermic [di″ -thur′ml, di″ -thur′mik] pertaining to diathermy; permeable by heat waves.

• diathermy [di′ -thur″me] the use of high-frequency electrical currents as a form of physical therapy and in surgical procedures. Diathermy is used in physical therapy to deliver moderate heat directly to pathological lesions in the deeper tissues of the body. Surgically, the extreme heat that can be produced by diathermy may be used to destroy neoplasms, warts, and infected tissues, and to cauterize blood vessels to prevent excessive bleeding. The technique is particularly valuable in neurosurgery and surgery of the eye. See also electrosurgery.

• surgical d. electrosurgery.

• diathesis [di-ath′ -sis] an unusual constitutional susceptibility or predisposition to a particular disease, e.g., bleeding diathesis, exudative diathesis.

• diatomic [di″ -tom′ik] 1. containing two atoms. 2. dibasic.

• diatoms unicellular algae, microscopic in size, with cell walls containing silica. Members of the family Diatomaceae. Their remains accumulate as geological deposits and are mined. See diatomaceous earth.

• diatrizoate [di″ -tri-zo′āt] a radiographic contrast agent no longer in common use.

• diaveridine [di″ -ver′ľ-dēn] a folic acid antagonist used as a synergist with sulfonamides against Eimeria spp.

• diazemuls see diazepam.

• diazepam [di-az′ -pam] a benzodiazepine tranquilizer used as an antianxiety agent, a skeletal muscle relaxant, anticonvulsant, and as an appetite stimulant.

• diazinon an organophosphorus insecticide, used in ear tags for cattle and in flea collars and rinses for dogs. Called also dimpylate. See also organophosphorus compound.

• diazo- the group −N₂− linked to one organic radical, general formula R₂C=N₂.

• diazotize [di-az′o-tīz] to introduce the diazo group into a compound.

• diazoxide [di″ z-ok′sīd] a benzothiadiazine derivative that inhibits insulin release, enhances glycogenolysis and inhibits the uptake of glucose; administered orally to treat hypoglycemia due to hyperinsulinism.

• dibasic [di-ba′sik] containing two replaceable hydrogen atoms, or furnishing two hydrogen ions.

• Dibothriocephalus [di-both″re-o-sef′ -l s] see D.

• dibromoethane [di-bro″mo-eth′ān] a fungistat used to protect stored grain from weevils that causes fatal edema, fibrosis and alveolar epithelialization of the lungs when eaten by livestock.

• dibromsalan one of two bromsalans (the other is tribromsalan) that, mixed in a variety of proportions, are used as treatments for liver flukes. See also bromsalans.

• dibucaine [di′bu-kān] a long-acting amide local anesthetic used topically and intraspinally in the form of the base and as the hydrochloride salt; the latter is also used intramuscularly for infiltration anesthesia. Called also cinchocaine. Has a special characteristic of needing only a small dose (about one-fortieth the dose of procaine).

• dibutyltin dilaurate a coccidiostat once used in commercial poultry.

• d. d. poisoning feeding to calves in error causes diarrhea and polyuria.

• DIC disseminated intravascular coagulation.

• dicamba a benzoic acid herbicide of very low toxicity. Very large doses cause anorexia, weight loss, and stiffness of the hindlimbs.

• dicarboxylic acid [di″kahr-bok-sil″ik-as″id] any organic molecule containing two carboxyl groups.

• dicelous, dicoelus [di-se′l s, di-se′l s] 1. hollowed on each of two sides. 2. having two cavities.

• Dicentra [di-sen′tr ] a genus of the Fumariaceae family of plants; contain an isoquinoline alkaloid that causes a syndrome of diarrhea, incoordination and other nervous signs. Includes D. cucullaria (dutchman’s breeches), D. canadensis (squirrel corn), D. eximia (turkey corn, wild bleeding heart), D. formosa (Pacific (western) bleeding heart), D. spectabilis (dutchman’s breeches, wild bleeding heart). Called also Bikukulla spp.

• dicephalus [di-sef′ -l s] a fetus with two heads. Called also derodidymus.

• dicephalus a fetus with two heads.

• Dichapetalum [di″k -pet′ -lum] African genus of the plant family Dichapetalaceae; contain large amounts of fluoroacetate; cause very sudden death, preceded in some cases by momentary tremor. Includes D. barteri, D. braunii, D. cymosum (D. venenatum, poison leaf, gibflaar), D. deflexum, D. guineense, D. heudelotii, D. macrocarpum, D. michelsonii, D. mossambicense, D. ruhlandiii, D. stuhlmanii, D. tomentosum, D. toxicarium (ratsbane).

• Dichelobacter nodosus [di-ke′lo-bak″t r] anaerobic bacterial species that causes infectious footrot of sheep and goats, in concert with Fusobacterium necrophorum. Previously called Bacteroides nodosus.

• dichlone a fungicide, algacide, pesticide, and herbicide used to treat seeds and water.

• dichloralphenazone [di″klor- l-fen′ -zōn] a mixture of chloral hydrate and antipyrine, a sedative and hypnotic agent.

• dichlormate a carbamate fungicide.

• dichloro-diphenyl-trichloroethane DDT.

• dichlorophen [di-klor′o-f n] a phenol derivative used as a cestocide; superseded except in combination with piperazine and other compounds.

• 2,4-dichlorophenoxyacetic acid [di-klor″o-f n-ok″se- -se′tic] a selective herbicide not known to be toxic at normal use rates in agriculture. Spraying may increase nitrate content of sprayed plants to toxic levels. Gastroenteritis can be seen in all species; myotonia has been reported in dogs. Called also 2,4-D.

• dichlorovos dichlorvos.

• dichlorphenamide [di″klor-fen′ -mīd] a systemically administered carbonic anhydrase inhibitor used to reduce intraocular pressure in glaucoma. Now generally superceded by topical analogues such as dorzolamide.

• dichlorvos [di-klor′vos] a broad-spectrum organophosphorus insecticide and anthelmintic. Can be combined with polyvinyl chloride resin; when administered orally or in collars or ear tags gives a slow release effect. Use banned in European Union.

• dichorial [di-kor′e- l] dichorionic.

• dichorionic [di-kor″e-on′ik] having two distinct chorions; said of dizygotic twins.

• Dichrocephala chrysanthemifolia small perennial African shrub, in the family Asteraceae; contains an unidentified toxin that causes diarrhea and abortion; plant toxic only when there are green shoots.

• dichroism [di′kro-iz- m] the quality or condition of showing one color in reflected and another in transmitted light.

• dichromate [di-kro′māt] a salt containing the bivalent Cr₂O₇ radical.

• dichromatic [di″kro-mat′ik] pertaining to or characterized by dichromatism.

• dichromatism [di-kro′m -tiz- m] see dichromatic vision.

• Dickinson–Nunamaker procedure a surgical technique for intra-articular reconstruction of the cranial cruciate ligament that involves a modification of the Paatsama procedure in which the fascia graft based on the craniolateral tibia is placed directly into the joint and emerges through a tunnel in the lateral femoral condyle before being sutured to itself.

• S-dichlorovinyl-l-cysteine a compound thought to be the toxic agent in trichlorethylene-extracted soybean meal poisoning.

• diclazuril a benzeneacetonitrile active against coccidia in chickens when used in feed. Used also for the treatment of equine protozoal myeloencephalitis.

• diclofenac [di-klo′fen-ak] a nonsteroidal anti-inflammatory agent, which may be used topically in ophthalmic diseases and in the treatment of actinic dermatitis. Use in livestock has been associated with a decline in the population of vultures in India due renal failure caused by the accumulation of residues.

• dicloxacillin [di-klok″s -sil′in] a semisynthetic penicillinase-resistant penicillin used primarily in the treatment of infections caused by penicillinase-resistant staphylococci.

• DICOMDigital Imaging and Communications in Medicine, an industry standard for image format and communications protocol for exchange of digital images.

• dicoria double pupil.

• dicoumarol, dicumarol [di-koo′m -rol] a potent anticoagulant that acts by inhibiting the synthesis of vitamin K-dependent clotting factors (prothrombin and factors VII, IX and X) in the liver; used in the prevention and treatment of thromboembolic disorders. Produced naturally by conversion of nontoxic coumarin in moldy sweet clover hay, lespepeza hay or sweet vernal hay. Eating the hay causes blood loss due to spontaneous hemorrhage. Formerly called bishydroxycoumarin. See also Melilotus, Anthoxanthum odoratum, Kummerowia (Lespedeza) stipulacea.

• dicrocoeliasis hepatic fascioliasis due to infection with Dicrocoelium dendriticum.

• Dicrocoelium [dik″ro-se′le- m] a genus of flukes (digenetic trematodes) in the family Dicrocoeliidae.

  • D. dendriticum (syn. D. lanceolatum) a liver fluke that infects most domestic and many wild animals. Has been reported in humans. Heavy infestation causes cirrhosis and biliary obstruction and a clinical syndrome of edema, anemia, and emaciation.
  • D. hospes occurs in the bile ducts of cattle in Africa.

• dicrotic [di-krot′ik] having the characteristic of dicrotism, e.g., the dicrotic notch of the pulse.

• dicrotism [di′kr $\stackrel{⌣}{o}$ -tiz- m] the occurrence of two sphygmographic waves or elevations to one beat of the pulse.

• dictyate a stage in the development of oocytes that are arrested at the same stage of meiotic prophase; the stage varies between species.

• Dictyocaulus [dik″te-o-kaw′l s] a genus of lungworms in the family Dictyocaulidae. Includes D. cameli (camels), D. eckerti (deer).

  • D. arnfieldi primarily a lungworm of donkeys but has little clinical effect in them. The infestation in horses is also clinically innocuous and the worms do not usually mature in this species.
  • D. filaria lungworms that cause a chronic disease in small ruminants. Clinical signs are limited to persistent cough, moderate dyspnea and loss of condition. Young sheep and goats may be severely affected, occasionally fatally.
  • D. viviparus the common lungworm of cattle causes several serious diseases including verminous pneumonia, acute interstitial pneumonia, and secondary bacterial pneumonia. The infestation is widespread and affects mainly young cattle. Massive larval intakes can cause a high mortality due to a peracute syndrome of interstitial pneumonia (hoose). More moderate infestation causes a syndrome of paroxysmal coughing, moderate dyspnea, and loss of condition. A few calves may die as a result of a secondary bacterial pneumonia. Warm moist autumnal conditions are most conducive to serious outbreaks.

• dictyoma [dik″te-o′m ] see diktyoma.

• dictyosome [dik″te-o-sōm′] stack of flattened, membrane-bound vesicles. see Golgi stack.

• dicyclomine [di-si′klo-mēn] an anticholinergic agent; used as a gastrointestinal antispasmodic and for urinary incontinence caused by derusor instability.

• didactylism [di-dak′t l-iz- m] the presence of only two digits on the paws of a usually four- or five-toed animal.

• didelphia [di-del′fe- ] the condition characterized by failure of proper fusion of the caudal part of the Muellerian or paramesonephric duct resulting in double cranial vagina, double cervix, and a divided uterine fundus with two single-horned uteruses. A normal feature of the female reproductive tract in rabbits and some marsupials.

• dideoxynucleotide a synthetic molecule lacking a hydroxyl group at both the 2′ and 3′ carbons of the sugar moiety. It is used in enzymatic DNA sequencing (e.g., Sanger sequencing) and as an anti-retroviral drug (e.g., HIV). Dideoxynucleotide triphosphates (ddNTPs) are readily incorporated into the growing DNA chain, but as they lack the 3′ hydroxyl group necessary to allow chain elongation, polymerization is terminated.

• didymalgia pain in a testis.

• didymitis [did″ -mi′tis] inflammation of a testis; orchitis.

• Didymotheca cupressiformis see Gyrostemon tepperi.

• didymous [did′ -m s] occurring in pairs.

• didymus [did′ -m s] testis.

• -didymus a word termination designating a fetus with duplication of parts or one consisting of conjoined symmetrical twins.

• diecious [di-e′sh s] sexually distinct; denoting species in which male and female genitals do not occur in the same individual. In botany, having staminate and pistillate flowers on separate plants.

• Dieffenbach forceps [de′f n-bahk] small, thumb-operated spring forceps that cross over so that releasing the blades causes the tips to close.

• Dieffenbachia seguine a tropical plant in the family Araceae commonly used as a house plant; contains calcium oxalate raphide crystals, and possibly other toxins; mastication of leaves causes severe irritation of the oral mucosa, especially swelling of the tongue. Called also D. maculata, D. picta, dumbcane.

• diehard nickname for the Scottish terrier.

• dieldrin [di-el′drin] see chlorinated hydrocarbons.

• dielectric [di″ -lek′trik] said of an insulating substance through which an electric force acts by induction but not conduction.

• diembryony [di-em′bre-on″e] the production of two embryos from a single zygote.

• diencephalic [di″ n-s -fal′ik] pertaining to or arising from the diencephalon.

  • d. infundibulum funnel-shaped diverticulum of the third ventricle which contributes to the formation of the caudal surface of the adenohypophysis, the distal part forming the neurohypophysis. Also referred to as the infundibular recess.
  • d. syndrome an uncommon syndrome seen in dogs in which a lesion in the diencephalon is associated with abnormalities of the hypothalamus and hypophysis, including electrolyte disturbances, abnormal thermoregulation, abnormal thirst and hunger, diabetes insipidus, altered levels of growth and other hormones, and autonomic nervous system dysfunction.

• diencephalon [di″ n-sef′ -lon] 1. the intermediate brain that consists of the thalamencephalon, hypothalamus, and subthalamus. 2. the more caudal of the two brain vesicles formed by specialization of the prosencephalon in the developing embryo. See also brainstem.

• dienestrol [di″ n-es′trol] a synthetic estrogen, related to stilbestrol.

• Dientamoeba [di″ent- -me′b] a genus of flagellates commonly found in the colon and appendix of primates and of humans.

  • D. fragilis occurs in the large intestine of humans and monkeys. Has been associated with diarrhea but its pathogenicity is unclear.

• dieresis [di-er′ -sis] 1. the division or separation of parts normally united. 2. the surgical separation of parts.

• diesel oil a common fuel on farms. Grazing ruminants are most likely to be poisoned by diesel fuel, especially cattle who find petroleum products palatable. Obvious clinical signs are anorexia, mild bloat, vomiting and aspiration pneumonia. The feces are oily and have a characteristic smell.

• diesoline see diesel oil.

• diestral shift in vaginal cytology of the bitch, the rapid change from predominantly superficial epithelial cells to intermediate and parabasal cells that occurs at the end of estrus and the beginning of diestrus.

• diestrus [di-es′tr s] the resting period between estral periods of animals characterized by dominance of the corpus luteum and progesterone secretion. The female rejects the male, blood concentrations of estrogens are minimal, and progesterone concentrations are high. This provides a physiological state in the uterus that is most conducive for implantation and growth of the developing fetus. Diestrus is terminated by luteolytic factors, such as prostaglandin F_2α secreted by the endometrium, if pregnancy does not occur.

• diet [di′ t] the customary amount and kind of food and drink taken by an animal from day to day; more narrowly, a diet planned to meet specific requirements of the animal, including or excluding certain foods. See also winter diet.

  • acid d. diets of low alkalinity which are fed to cows to prevent bovine parturient hypocalcemia (milk fever). The diet in the 4 weeks preceding parturition, which is ordinarily alkaline, is supplemented with calcium chloride, and aluminum and magnesium sulfates, to reduce this alkalinity. See also dietary cation-anion difference.
  • bland d. typically, a highly digestible, low fat diet that is free from any irritating or stimulating foods.
  • calcium homeostatic d. a diet aimed at maintaining normal blood concentrations of calcium in recently calved cows.
  • calculolytic d. formulated to aid in the dissolution of struvite uroliths. Usually provides a low intake of protein, restricts phosphorus and magnesium, and acidifies the urine. Additional salt may also be included. These have been used successfully in dogs and cats.
  • deficient d. see nutritional deficiency disease.
  • drought feeding d. see drought feeding.
  • elemental d. contains nutrients as small-molecular-weight compounds, i.e., proteins as amino acids or peptides, carbohydrates as oligosaccharides or monosaccharides, and fats as medium-chain triglycerides. These nutrients are readily absorbed with little or no digestion. Used in the treatment of gastrointestinal disease. Called also monomeric diet.
  • elimination d. one for diagnosing food allergy, based on the sequential omission of foods that might cause the clinical signs in the patient.
  • geriatric d. may vary in composition; generally, they are formulated to provide optimal levels of high quality protein sources, lower energy intake, and increased digestibility.
  • gluten-free d. one without wheat, rye, barley, buckwheat, or oats or related products.
  • high-calorie d., high-energy d. one that furnishes more calories than needed for maintenance; used to increase body condition, in recovery from illness and for maintenance under stressful conditions.
  • high-fiber d. one relatively high in dietary fiber; in dogs and cats, used in the management of large and small bowel diarrhea, diabetes mellitus, constipation, and obesity.
  • high-protein d. one containing large amounts of high-quality protein; used in the management of dogs and cats recovering from illness.
  • home-prepared d. one prepared in the home kitchen, in contrast with commercially prepared pet foods.
  • hydrolyzed d. one in which the proteins have been hydrolyzed to small molecular weight so they are of insufficient size and structure to induce antigenic recognition. Used in the management of food allergies in dogs and cats.
  • hypoallergenic d. one formulated to avoid suspected allergens; usually used in the management of allergic skin or bowel disease.
  • liquid d. a diet limited to liquids or to foods that can be changed to a liquid state.
  • low-calorie d. one containing fewer calories than needed to maintain weight; normally used in management of obesity in dogs and cats.
  • low-fat d. one containing limited amounts of fat; used in the management of pancreatic disease, bowel disease, and obesity in dogs and cats.
  • low-fiber d. see low-residue diet (below).
  • low purine d. in dogs and cats, generally a low-meat diet.
  • low-residue d. one with a minimum of cellulose and fiber and restriction of connective tissue found in certain cuts of meat. It is prescribed for irritations of the intestinal tract, after surgery of the large intestine, in partial intestinal obstruction, or when limited bowel movements are desirable. Called also low-fiber diet.
  • low vitamin A d. one containing low concentrations of vitamin A; in dog and cat diets, this would mean little or no organ meats. The only probable indication for such a diet is in the treatment of hypervitaminosis A.
  • lower urinary tract disease d. one that promotes acidification of the urine and containing restricted magnesium and phosphorus, and sometimes increased salt.
  • monomeric d. see elemental diet (above).
  • phosphate-restricted d. one containing restricted amounts of phosphorus; used in the management of chronic renal disease.
  • polymeric d. meal replacement diets; fed to animals with almost normal gastrointestinal function. Proteins, fats, and carbohydrates are present in high molecular weight forms.
  • sodium-restricted d. used in management of congestive heart failure and systemic hypertension in dogs and cats.

• dietary [di′ -tar″e] 1. pertaining to diet. 2. a course or system of diet.

  • d. cation-anion difference prepartum has a major influence on the incidence of bovine parturient hypocalcemia (milk fever) in dairy cattle and, in the control of the disease, is manipulated so as to result in a metabolic acidosis that facilitates the mobilization of calcium. Defined as milliequivalents of (Na+K)–(Cl+S) per kg DM diet.
  • d. hepatic necrosis see hepatosis dietetica.
  • d. indigestion see indigestion.
  • d. mineral tolerance concentrations of minerals in the diet that animals will tolerate without impairing their productivity.
  • d. requirement the amount of each dietary constituent required in the diet for the animal to produce efficiently. In some individuals the requirements are abnormally high compared to the rest of the population.

• dietetic [di″ -tet′ik] pertaining to diet or proper food.

  • d. microangiopathy occurs in pigs on diets deficient in selenium and vitamin E.
  • d. scours see dietary diarrhea.

• dietetics [di″ -tet′iks] the science of diet and nutrition.

• diethyl ether [di-eth′ l] see ether (1).

• diethylcarbamazine [di-eth″ l-kahr-bam′ -zēn] an antifilarial or microfilaricidal (active against the larval stages during molting) agent used in dogs as the citrate salt for the prevention of heartworm infection. Used also for the treatment of ascarids in dogs and immature lungworms in cattle and sheep.

• diethyldithiocarbamate a carbamate insecticide; causes spinal cord tract degeneration in chickens.

• diethylene glycol [di-eth′ l-ēn gli′kol] an industrial solvent. Causes CNS depressive signs and hepatic damage, similar to ethylene glycol.

• diethylenetriamine penta-acetic acid (DTPA) [di-eth″ l-ēn-tri′-mēn pen″t- -se′tik as′id] a chelating agent; used in nuclear medicine in preparing radiopharmaceuticals, e.g., ^99mTc-DTPA. Called also pentetic acid.

• diethylstilbestrol (DES) [di-eth″ l-stil-bes′trol] a synthetic estrogen. Has been used in cattle to treat infertility, but its use is prohibited in food animals in the US. Sometimes used in dogs to treat misalliance and for urinary incontinence in ovariectomized bitches, but its use is limited by its myelotoxic effects.

• diethylthiambutene hydrochloride a synthetic opioid analgesic with an effect like that of morphine; previously used in veterinary medicine. Highly toxic to cats. Can cause convulsions if injected intravenously. Called also Themalon.

• diethyltoluamide (DEET) [di-eth″ l-tol-u′ -mīd] an insect repellent used on dogs and cats. Toxicity signs include vomiting, tremors, and seizures.

• dietotherapy [di″ -to-ther′ -pe] the scientific regulation of diet in treating disease, especially important in patients with inborn errors of metabolism and various other metabolic diseases.

• difenacoum a potent, synthetic anticoagulant rodenticide with prolonged antagonism of vitamin K. In many countries, use is restricted to licensed applicators.

• difenoxin [di″f -nok′sin] a meperidine derivative used to control diarrhea.

• Diff-Quik stain a commercial name for a Romanowsky stain which can be applied rapidly to smears of blood, aspirated cells or exudate.

• differentiation [dif″ r-en″she-a′sh n] 1. the distinguishing of one thing from another. 2. the act or process of acquiring completely individual characteristics, such as occurs in the progressive diversification of cells and tissues in the embryo, e.g., sex differentiation. 3. increase in morphological or chemical heterogeneity.

• diffraction [dľ-frak′sh n] the bending or breaking up of a ray of light into its component parts.

  • x-ray d. a method used to determine the three-dimensional structure of the single object, e.g., protein molecule, that composes the crystal. Based on recording and analyzing the diffraction pattern of an x-ray beam passing through a crystalline structure, either organic or inorganic.

• digital image a computer graphic file made up of a matrix of picture elements (pixels).

• digital image processing computer software used to modify the appearance of a digital image; used in digital radiology.

  • d. i. p. correction to replace erroneous pixel values from non-functioning image chip elements equal to the average of the surrounding pixel values; compensation of different sensitivity of detector elements in the systems by making a flat field x-ray exposure and to apply correction factors so that each detector outputs an equal signal.
  • d. i. p. image leveling determines the midpoint of the pixel values to be displayed leading to a change in the brightness of the image.
  • d. i. p. image sharpening convolution filter and unsharp mask filtering makes a blurred image; the degree of blurring is dependent on the number of pixels selected (kernel size); this new blurred image is then subtracted from the original image and the subtracted image is then added back to the original image to accentuate the edges of structures.
  • d. i. p. windowing determines the range of pixel values about the level to be displayed leading to a change in the image contrast.

• diffusate [dľ-fu′zāt] material that has diffused through a membrane.

• diffuse [dľ-fūs′] 1. not definitely limited or localized. 2. to pass through or to spread widely through a tissue or substance.

  • d. intravascular coagulation see disseminated intravascular coagulation.

• diffusing capacity [dľ-fūs′ing] the rate at which a gas diffuses across the alveolar–capillary membrane per unit difference in the partial pressure of the gas across the membrane, expressed in ml/min/mmHg. Usually tested by the inhalation of very low levels of carbon monoxide. Used to assess pulmonary function in respiratory disease.

• diffusion [dľ-fu′zh n] 1. the state or process of being widely spread. 2. the spontaneous mixing of the molecules or ions of two or more substances resulting from random thermal motion; its rate is proportional to the concentrations of the substances, and it increases with the temperature. In the body fluids, the molecules of water, gases, and the ions of substances in solution are in constant motion. As each molecule moves about, it bounces off other molecules and loses some of its energy to each molecule it hits, but at the same time it gains energy from the molecules that collide with it. The rate of diffusion is influenced by the size of the molecules; larger molecules move less rapidly, because they require more energy to move about. Molecules of a solution of higher concentration move more rapidly toward those of a solution of lesser concentration; in other words, the rate of movement from higher to lower concentration is greater than the movement in the opposite direction.

  • d. coefficient the number of milliliters of a gas that will diffuse at a distance of 0.001 mm over a square centimeter surface per minute, at 1 atmosphere of pressure. The diffusion coefficient for any given gas is proportional to the solubility and molecular weight of the gas. The diffusion coefficient for oxygen is 1.0, for carbon dioxide it is 20.3, and for nitrogen it is 0.53. The diffusion capacity of a gas varies directly with the diffusion coefficient.
  • facilitated d. mechanisms in intestinal absorption that assist the passage of those products of digestion, which cannot occur by simple diffusion, across the intestinal cell membranes. They include a carrier mechanism involving proteins, and active transport that provides energy from the breakdown of high-energy phosphate bonds.
  • Fick’s first law of d. see Fick’s first law of diffusion.
  • d. hypoxia a transient hypoxic episode after the cessation of nitrous oxide anesthesia if air is inhaled instead of pure oxygen; caused by the rapid outward diffusion of nitrous oxide and the re-introduction of nitrogen into the alveoli resulting in dilution of the oxygen that is present.

• diflorasone diacetate [di-flor′ -sōn] a corticosteroid used topically in treatment of inflammatory skin diseases.

• difloxacin a fluoroquinolone antibiotic.

• diflubenzuron an ectoparasiticide similar to lufenuron.

• diflunisal [di-floo′nľ-s l] a salicylic acid derivative that, like aspirin, has analgesic and anti-inflammatory properties.

• difluoromethylornithine see eflornithine hydrochloride.

• difluorotetrachloroethane see tetrachlorodifluorethane.

• digastric [di-gas′trik] 1. having two bellies. 2. digastric muscle. See Table 12.

• Digenea a subclass of trematodes (class Trematoda) that includes most of the flukes of veterinary importance.

• digenean pertaining to or of the nature of members of the fluke subclass Digenea.

• digenetic [di″j -net′ik] 1. having two stages of multiplication, one sexual in the mature forms, the other asexual in the larval stages. 2. belonging to the subclass Digenea (flukes).

  • d. trematodes see Digenea.

• DiGeorge syndrome [dľ-jorj′] an immunodeficiency syndrome in humans caused by a deletion in chromosome 22. Among other potential defects (e.g., heart defect, cleft palate, etc.), it is associated with thymic hypoplasia or aplasia and absence of T lymphocytes, resulting from a congenital absence of the third and fourth branchial pouches. Also referred to as 22q11.2 deletion syndrome.

• digesta alimentary tract contents undergoing digestion.

• digestant [di-jes′t nt] 1. assisting or stimulating digestion. 2. an agent capable of aiding digestion.

• digestibility the proportion of a feed or diet that can be digested by the normal animal of the subject species.

  • true d. the endogenous source of a fecal content of a feed moiety under examination is taken into account when assessing the input–output relationship of the moiety.

• digestible having the quality of being able to be digested.

  • d. energy the proportion of the potential energy in a feed that is in fact digested.
  • d. protein see digestible protein.
  • total d. nutrients see total digestible nutrients.

• digestion [di-jes′ch n] 1. the act or process of converting food into chemical substances that can be absorbed into the blood and utilized by the body tissues. 2. the subjection of a substance to prolonged heat and moisture, so as to disintegrate and soften it. Digestion is accomplished by physically breaking down, churning, diluting, and dissolving the food substances and also by splitting them chemically into simpler compounds. Carbohydrates are eventually broken down to monosaccharides (simple sugars); proteins are broken down into amino acids; and fats are absorbed as fatty acids, monoglycerides, and glycerol (glycerin). The digestive process takes place in the alimentary canal or digestive system. The salivary glands, liver, gallbladder, and pancreas are located outside the alimentary canal, but they are considered accessory organs of digestion because their secretions provide essential enzymes and other substances.

  • avian d. differs markedly from mammals in the mouth; there are no teeth, dental functions being performed by the beak and the muscular gizzard; the esophagus, in other than owls and insectivorous species, has one or two crops, dilations where ingesta are held temporarily.
  • enzymatic d. most digestive processes in monogastric animals are enzymatic brought about by enzymes secreted into the lumen of the gastrointestinal tract and enzymes located at the brush borders of the intestinal epithelium.
  • d. error any disruption of the normal digestive process; caused by abnormal ingesta, either chemically or physically, or by an error in the physiological and biochemical processes that constitute digestion.
  • gastric d. digestion by the action of gastric juice.
  • impaired d. see maldigestion.
  • intestinal d. digestion by the action of intestinal juices, bile, and pancreatic juice.
  • luminal phase d. the stage of the digestion of fats that goes on in the lumen of the intestine; as distinct from the mucosal phase that occurs in the epithelial cells.
  • pancreatic d. digestion by the action of pancreatic juice.
  • peptic d. gastric digestion by pepsin.
  • primary d. digestion occurring in the gastrointestinal tract.
  • ruminant d. characterized by the fermentative functions that are carried on in the forestomachs. Cellulose is readily digested with the output of short-chain fatty acids being the chief energy source for the animal. Nonprotein nitrogen is utilized by the ruminal bacteria for the manufacture of protein that is later available for the satisfaction of the animal’s protein needs.
  • salivary d. the change of starch into maltose by the saliva; most marked in humans.
  • d. tests see starch digestion test, lactose digestion test, gelatin digestion test.

• digestive [di-jes′tiv] pertaining to digestion.

  • d. enzymes include salivary (amylase), gastric (pepsin), pancreatic (trypsin, chymotrypsin, amylase, lipase), small intestinal mucosa (carbohydrases including isomaltase, lactase, maltase, sucrase, trehalase).
  • d. inoculant administered mostly to neonatal calves and foals, intended to provide an inoculum of beneficial bacteria and protozoa essential to proper digestion and usually picked up from the environment. In many commercial products, the irresistible temptation to include other materials, including dietary essential vitamins and minerals, clouds the effect of the inoculant, and may, as in iron poisoning in foals, cause disaster.
  • d. system the organs that have as their particular function the ingestion, digestion and absorption of food or nutritive elements. They include the mouth, teeth, tongue, pharynx, esophagus, stomach, and intestines. The accessory organs of digestion, which contribute secretions important to digestion, include the salivary glands, pancreas, liver, and gallbladder. Birds have an unusual system in that there are no teeth and no soft palate in most. There is a pregastric buffer, the crop; the stomach is separated into two organs, one secretory (the proventriculus) and one muscular (the gizzard), and the large intestine is replaced by a double cecum. The rectum empties into a cloaca, which is shared with the urogenital tract. The ruminant system is complicated by the presence of a compound stomach made up of the reticulum, rumen, omasum and abomasum, and there are no upper incisor teeth. The peculiarities of horses are the greatly distended large intestine and the absence of a gallbladder.
  • d. tract the digestive system less the ancillary organs of salivary glands, liver and pancreas; the luminal organs through which food passes. See also alimentary canal.

• digit [dij′it] a toe in cats, dogs and chickens, a foot in the horse, a claw or cleat in cattle, sheep, goats and pigs. Called also a cleat in sheep.

• digital [dij′ľ-t l] emanating from or pertaining to the digit.

  • d. cushion a wedge-shaped mass of white and elastic fibers mixed with some fat and islands of cartilage overlying the frog of the horse’s hoof and acting as a shock absorbing mechanism.
  • d. dermatitis see digital dermatitis.
  • d. pad see footpad.
  • d. palpation method of physical examination of a patient using a finger.
  • d. sheath a common synovial sheath shared, in ruminants and horses, by the superficial and deep digital flexor tendons.
  • ovine d. dermatitis see interdigital dermatitis.

• digital radiography electronic recording of an x-ray image in place of film radiography. See also digital radiography, digital subtraction radiology.

  • direct d. r. utilizes a large area selenium plate coupled with a transistor array; x-ray interaction in the selenium layer releases electrons that are used to form an electric signal that leads to generation of a radiographic-like computer image.
  • indirect d. r. x-ray sensitive fluorescent screen coupled to a light-sensitive silicone panel coupled to a transistor array, that releases electrons that are used to form an electrical signal which leads to generation of a radiographic-like computer image.
  • indirect charge-coupled device (CCD) d. r. an x-ray fluorescent screen is coupled to a light sensitive charge-coupled device (CCD) which releases electrons that are used to form an electrical signal leading to generation of a radiographic-like computer image.

• digitalin [dij″ľ-tal′in] a mixture of digitalis glycosides extracted from the seeds of Digitalis purpurea.

• Digitalis [dij″ľ-tal′is] a genus of herbs in the family Scrophulariaceae; contains digitalis-related (cardenolide) cardiac glycosides, e.g., digoxin, lanatoside. Includes D. lanata (woolly foxglove, Grecian foxglove), D. purpurea (purple foxglove). Sources of commercial digitalis.

• digitalis [dij″ľ-tal′is] dried leaf of Digitalis purpurea; used as a cardiotonic agent. All drugs prepared from this digitalis leaf are members of the same group and principles of administration are the same. The drugs vary according to speed of action and potency. Digitalis can be very effective in the treatment of various cardiac conditions, but its therapeutic range is narrow; a therapeutic dose is only about one-third less than the dose that causes intoxication. Intoxication is manifested by vomiting, diarrhea, arrhythmia and heart failure.

  • d. glycosides digitoxin, digoxin.

• digitalization [dij″ľ-t l-ľ-za′sh n] the administration of digitalis in a dosing schedule designed to produce and then maintain optimal therapeutic concentrations of its cardiotonic glycosides.

• Digitaria grass genus containing a large number of valuable species in the family Poaceae. Contains cyanogenic glycosides, can cause cyanide, and possibly oxalate, poisoning. Includes D. eriantha (D. decumbens), D. didactyla, D. saginata, D. sanguinalis. Called also crabgrass, pangola grass, summer grass.

  • D. exilis seed is used for human and animal food, and the plant for pasture or hay. Called also hungry rice, acha.

• digitation [dij″ľ-ta′sh n] 1. a finger-like process. 2. surgical creation of a functioning digit by making a cleft between two adjacent metacarpal bones, after amputation of some or all of the digits.

• digitiform [dij′ľ-tľ-form] digit-like.

• digitigrade [dij′ľ-tľ-grād″] a form of locomotion in which the animal walks only on its digits (or strictly the pads that support the proximal and distal interphalangeal joints), e.g., dogs, contrasted with plantigrade, in which the animal walks on its metatarsi, metacarpi, metapodials, e.g., bears, humans, and also contrasted with unguligrade in which the animal walks on the tips of its digits via hooves.

• digitonin [dij″ľ-to′nin] a saponin in Digitalis purpurea. It has no effect on heart muscle.

• digitoxigenin [dij″ľ-tok″sľ-je′nin] a metabolic product of the cardioactive alkaloids, digitoxin and gitoxin.

• digitoxin [dij″ľ-tok′sin] a cardiac glycoside originally obtained from Digitalis purpurea and other species of the same genus; used in the treatment of congestive heart failure. It has a longer elimination half life than digoxin and is eliminated principally by hepatic metabolism, whereas digoxin is eliminated through the kidneys.

• digitoxose [dij″ľ-tok′sōs] a desoxy sugar, a metabolic product of digitoxin and gitoxin.

• diglossia [di-glos′e- ] bifid tongue.

• diglyceride [di-glis′ r-īd] a glyceride containing two fatty acid molecules in ester linkage. Called also diacylglycerol.

• dignathus [dig-na′th s] a fetus with two lower jaws.

• digoxin [dľ-jok′sin] a cardiotonic glycoside originally obtained from the leaves of Digitalis lanata; used in the treatment of congestive heart failure, atrial fibrillation or both.

• DiGuglielmo’s syndrome [de goo-lyel′mo] erythroleukemia.

• digyny fertilization of diploid oocyte resulting in triploid zygote.

• dihematoporphyrin ether a photosensitizing agent used in the photodynamic treatment of neoplasms.

• dihydrocodeine [di-hi″dro-ko′dēn] an opioid analgesic and antitussive.

• dihydrocodeinone [di-hi″dro-ko′de-nōn] hydrocodone.

• dihydroergotamine [di-hi″dro- r-got′ -mēn] hydrogenated ergotamine, an α-adrenergic blocking agent and vasoconstrictor.

• dihydrofolate reductase [di-hi″dro-fo′lāt re-duk′tās] enzyme catalyzing the conversion of folate to 5,6,7,8-tetrahydrofolate, which is the key carrier of one-carbon units in purine and pyridime synthesis, the pathway for the breakdown of histidine and the synthesis of S-adenosylmethionine from S-adenosylhomocysteine. This enzyme is the target for methotrexate, which inhibits enzyme action, a key means of inducing remissions in acute leukemias.

• dihydrolipoic acid the reduced form of lipoic acid, an essential coenzyme of pyruvate dehydrogenase enzyme complex.

• dihydrostreptomycin [di-hi″dro-strep″to-mi′sin] an aminoglycoside antibiotic produced by the hydrogenation of streptomycin; ototoxic with damage to sensory end organs.

• dihydrotachysterol [di-hi″dro-tak-is′t -rol] a vitamin D analogue; used as an antihypocalcemic agent in the treatment of hypoparathyroidism, particularly in cats following thyroidectomy.

• dihydrotestosterone [di-hi″dro-tes-tos′t -rōn] reduced, more active form of testosterone in males, critical for development and function of male excurrent tract. 5-Alpha reductase inhibitors prevent synthesis of d. and are used for treatment of benign prostatic hyperplasia in dogs; associated with follicular atresia in the female.

• dihydroxyanthraquinone see danthron.

• dihydroxycholecalciferol [di″hi-drok″se-ko″l -kal-sif′ -rol] a group of active metabolites of cholecalciferol (vitamin D₃) numbered according to the carbon atom(s) on which a hydroxyl group is substituted. 1,25-Dihydroxycholecalciferol (calcitriol) is the most active derivative; the 25-hydroxylation occurs in the liver under the influence of substrate concentration whereas the 1-hydroxylation or 24-hydroxylation occurs subsequently in the kidney mitochondria. 1-hydroxylation is under regulation by parathyroid hormone in response to decreases in plasma calcium concentration. 1α,25-Dihydroxycholecalciferol acts like a steroid hormone stimulating calcium absorption from the small intestine and calcium mobilization from bone. 24,25-Dihydroxycholecalciferol is an essential hormone for the process of bone fracture healing.

• dihydroxycoumarin glycoside a group of plant toxins including daphnin and daphnetin in Daphne spp. and other plants.

• 3,4-dihydroxyphenylalanine [di″hi-drok″se-fen″ l-al′ -nēn] dopa.

• 1,25-dihydroxyvitamin D₃ [di″hi-drok″se-vi′t -min] see dihydroxycholecalciferol.

  • 1,25-dihydroxyvitamin D₃ glycoside [di″hi-drok″se-vi′t -min] the calcinogenic agent in Solanum glaucophyllum (S. malacoxylon) and related plants.

• diiodohydroxyquinoline iodoquinol.

• di-iodotyrosine, diiodotyrosine [di″i-o″do-ti′ro-sēn] a step in the pathway to the formation of thyroglobulin in the thyroid gland. I₂ conjugates with tyrosine to form compounds that are then coupled to form thyronines, the principal thyroid hormones.

• dikkop cardiac form of African horse sickness.

• dikoor see yellow bighead.

• diktyoma [dik″te-o′m ] a tumor of the ciliary epithelium resembling embryonic retinal tissue in structure.

• dilaceration [di-las″ r-a′sh n] 1. a tearing apart, as of a cataract. In dentistry. See discission. 2. in dentistry, an abnormal angulation or curve in the root or crown of a formed tooth.

• dilan a chlorinated hydrocarbon used as an insecticide.

• dilatation [dil″ -ta′sh n] the condition, as of an orifice or tubular structure, of being dilated or stretched beyond normal dimensions. See under anatomical location, e.g., esophageal, cardiac, intestinal, gastric, pupillary.

  • d.–torsion syndrome see gastric dilatation-volvulus.

• dilated pupil syndrome see dysautonomia. Called also Key–Gaskell syndrome.

• dilation [di-la′sh n] the act of dilating or stretching. See also dilatation.

• dilator [di-la′t r] a structure (muscle) that dilates, or an instrument used to dilate.

  • d. pupillae muscle dilator muscle of the pupil.

• diltiazem [dil-ti′ -z m] a non-dihydropyridine calcium-channel blocking agent used to produce peripheral and coronary vasodilation in the management of heart disease and as an antiarrhythmic in dogs. It is more specific for AV nodal slowing of conduction and less specific for the vascular calcium channels.

• diluent [dil′u- nt] 1. diluting. 2. an agent that dilutes or renders less potent or irritant.

  • semen d. see semen extender.

• dilution [di-loo′sh n] 1. reduction of concentration of an active substance by admixture of a neutral agent. 2. a substance that has undergone dilution.

  • limiting d. a method of obtaining a pure culture of bacteria or virus by subculturing from the highest dilution in which the organism is demonstrably present.
  • serial d. 1. the progressive dilution of a substance or infectious agent in a series of tubes or wells in a tray in predetermined ratios, e.g., 2-fold or 10-fold dilution steps. 2. a method of obtaining a pure bacterial culture by rapid transfer of a small amount of material from one nutrient medium to a succeeding one of the same volume.

• DIM days in milk.

• dimenhydrinate [di″m n-hi′drľ-nāt] an H₁-blocker antihistamine used as an antinauseant and antiemetic in the treatment of motion sickness in dogs and cats. Of limited usefulness in treating pruritus associated with allergic skin disease. Sedation is a common side effect.

• dimensional data see dimensional data.

• dimer [di′m r] chemical compound formed by the union of two identical molecules.

• D-dimer test a test for the presence of D-dimers, which are cross-linked fibrin degradation products and markers for clot lysis. Used in diagnosing and monitoring treatment for disseminated intravascular coagulation (DIC).

• dimercaprol a chelating agent used in the treatment of heavy metal poisoning. The drug forms a relatively stable compound with arsenic, mercury, gold, and certain other metals, thus protecting the vital enzyme systems of the cells against the effects of the metals. It is sometimes diluted with water and used to lavage the stomach, some of the solution being permitted to remain in the stomach. At the dose concentrations required for effect in ruminants, dimercaprol is itself poisonous. The drug has a very disagreeable skunk-like or sulfurous odor and should be handled carefully to avoid spilling. Called also British antilewisite, BAL, dimercaptopropanol.

• dimercaptopropanol see dimercaprol.

• dimercaptosuccinic acid (DMSA) an organosulfur compound used primarily to chelate lead in lead poisoned patients. Called also succimer.

• dimethicone [di-meth′ľ-kōn] a silicone oil used as a skin protective and as an antifoaming agent in the treatment of frothy bloat in ruminants.

  • activated d. see simethicone.

• dimethindene a histamine type 1 (H₁)-antagonist; an antihistamine.

• dimethoate an organophosphorus contact insecticide used principally as a premise spray; capable of causing poisoning. Chronic intake causes salivation and diarrhea in calves. Use banned in several countries.

• dimethyl phthalate (DMP) an insect repellent, sometimes used topically on dogs to discourage licking of skin lesions.

• dimethyl sulfoxide (DMSO) see DMSO.

• p-dimethylaminoazobenzene [di-meth″ l- -me″no-a″zo-ben′zēn] see butter yellow.

• dimethyldisulfide a hemolytic agent produced in the rumen by bacterial action on S-methylcysteine sulfoxide; present in Brassica spp. plants.

• dimethylnitrosamine [di-meth″ l-ni-tro′s -mēn] a potent hepatotoxin in herring meal. Chronic poisoning causes toxic hepatosis and changes reminiscent of neoplasia and the substance is now regarded as a carcinogen.

• dimethylnortestosterone see mibolerone.

• dimethylpolysiloxane dimethicone.

• dimethyltryptamine [di-meth″ l-trip′t -mēn] a group of alkaloids found in the grass Phalaris aquatica and known to be closely associated with the acute form of poisoning with this plant.

• dimetilan a chlorinated hydrocarbon used as an insecticide.

• dimetria a rare condition characterized by a double uterus.

• dimetridazole [di″m -tri′d -zōl] a nitrothiazole compound used therapeutically and prophylactically in histomoniasis in turkeys but banned for this use in many countries. Poisoning is manifested by infertility and hepatic and renal insufficiency.

• dimidium bromide a compound used in the treatment of trypanosomiasis.

• diminazene [dľ-min′ -zēn] a diamidine antiprotozoal agent used as the aceturate.

• diminishing returns the characteristic of any production system in which increases in variable inputs result in increasing reduction of total output. An indicator of when to stop making additional inputs to the system, when the input exceeds the additional output.

• Dimorphandra South American genus of plants in the legume family Caesalpiniaceae; contain an unidentified toxin that causes nephrosis in cattle. Includes D. gardneriana, D. mollis (faveira).

• dimorphic [di-mor′fik] see dimorphic fungus.

• dimorphism [di-mor′fiz- m] the quality of existing in two distinct forms.

  • sexual d. 1. physical or behavioral differences associated with sex; males and females of the same species are different in appearance. 2. having some properties of both sexes, as in the early embryo and in some hermaphrodites.

• Dimorphotheca South African genus of plants in the family Asteraceae; some species contain cyanogenic glycosides and poison livestock. Includes D. cuneata (Karoo bietou, witgousblom). Called also Osteospermum, South African daisy, bietou, madeliefies.

• dimple [dim′p l] see myotonic dimple.

• dimpylate see diazinon.

• Dina parva a leech found in the nasal cavity of aquatic birds.

• Dingmann clamp a heavy-duty bone and cartilage clamp; scissor action with ratcheted handles and curved, heavily serrated blade faces that enclose an oval space when closed.

• dingo Australian wild dog (Canis lupus dingo) a medium-sized, yellow to red dog with large pricked ears and a bushy tail. Opportunistic predator; mainly mammals, rarely farm livestock.

• dingy used as a description of fleece wool; the wool is lacking in brightness.

• dinitolmide, dinitolamide a nitrobenzamide anticoccidial agent that acts on first generation schizonts and inhibiting sporulation of oocysts.

• dinitro compounds a group of herbicides including 2,4-dinitrophenol, dinitro-orthocresol and dinoseb. Although relatively nontoxic at recommended use rates because of toxicity and environmental effects they have been banned from use in the US and most other countries. Signs of poisoning include dyspnea, sweating, thirst, weakness, prostration and death.

• dinitro herbicide effective herbicides, nontoxic unless administered in concentrate form or if the material as supplied contains a toxic contaminant.

• dinitro-o-toluamide a toxic coccidiostat; can cause ataxia, torticollis and reduced growth.

• dinitro-orthophenol relatively nontoxic wood preservative.

• dinitroaniline a group of preemergence herbicides of low toxicity for animals. Accidental poisoning causes diarrhea, nervousness, and failure to gain weight.

• dinitrochlorobenzene (DNCB) [di-ni″tro-klor″o-ben′zēn] a hapten whose application to the skin results in a contact hypersensitivity. Sometimes used to test for ability to produce type IVor delayed type hypersensitivity reactions.

• dinitrocresol see dinitro-orthocresol.

• dinitro-orthocresol (DNOC) once a valuable herbicide but it can cause deaths in animals exposed to high doses by inhalation, percutaneous absorption, or ingestion. Signs of poisoning include restlessness, sweating, dyspnea, and collapse. Ruminants are also subject to intravascular hemolysis, methemoglobinemia, and hypoproteinemia. Chronic poisoning causes cataracts. Now banned from use.

• 2,4-dinitrophenol, dinitrophenol (DNP) [di-ni″tro-fe′nol] 1. DNP; an inhibitor of oxidative phosphorylation. Acts by uncoupling electron flow from phosphorylation. Used as a haptenic immunogen in immunology. 2. A herbicide toxic to animals. Effects are similar to those of dinitro-orthocresol. See also dinitro compounds. Now banned from use.

• 4-dinitrophenol once widely used herbicide and pesticide that persists in contaminated soils and groundwater, causing health and environmental hazards. Reported as toxic to companion animals an foals with clinical signs of profuse salivation, vomiting, sweating, tremors, and convulsions followed by death. Now banned from use in the US and most countries. In humans can induce very rapid fat loss when taken orally but with considerable risk to life.

• Dinobdella [di″nob-del′ ] a leech of the class Hirudinea.

  • D. ferox found in the pharynx of ruminants and the upper respiratory tract of dogs, monkeys and humans.

• dinobdelliasis infestation of animal species with nasal leech Dinobdella ferox.

• dinoflagellates [di″no-flaj′ -lāts] minute aquatic protozoa; they produce red pigment and toxins that are taken up by shellfish without apparent ill effect, but the toxin is not metabolized, and the shellfish may poison animals if eaten.

• dinoprost prostaglandin F_2α stimulates contraction of the myometrium and luteolysis. Used as the tromethamine and administered to induce abortion or parturition, to synchronize estrus, and for the treatment of some ejaculatory disorders in the stallion.

• dinoseb a phthalmic acid derivative herbicide that has caused poisoning in range chickens when used at standard dose rates. Includes dinoseb 136. Banned for use in the US and European Union.

• dinotefuran a neonicotinoid class insecticide used to prevent fleas and ticks on dogs and fleas on cats; used in combination with pyriproxifen or permethrin.

• Dioctophyme a genus of nematodes in the family Dioctophymidae. Includes Dioctophyme renale, a very large nematode found in the kidneys and other organs of dogs and wild carnivores and occasionally ruminants. May be severely destructive and cause fatal uremia.

• dioctophymosis infection with the kidney worm Dioctophyme renale.

• dioctyl sodium sulfosuccinate (DSS) docusate sodium; used pharmacologically as a fecal softener, wetting agent and cathartic. Sometimes used as an enema to treat persistent meconium impactions in neonatal foals, but can cause irritation and excessive straining. Overdosing in horses for the treatment of impaction colic can cause deaths preceded by paralytic ileus, diarrhea, and severe dehydration.

• diode [di′od] a piece of equipment with two terminals that carries electrical current in one direction only.

• Diodontidae a family of venomous fishes closely related to the pufferfishes. Called also toadfish, porcupinefish, globefish.

• dioestrus see diestrus.

• diol an organic compound containing two hydroxy groups, a dihydric alcohol. Called also glycol.

• Dioon Central American cycad genus in the family Zamiaceae; contains highly toxic azoxyglycoside compounds causing diarrhea, posterior ataxia and hepatic necrosis in grazing animals. Includes D. edule.

• diopter (D) [di-op′t r] unit for describing refractive power of a lens, being the reciprocal of the focal length when expressed in meters.

• dioptric [di-op′trik] pertaining to refraction or to transmitted and refracted light; refracting.

• dioptrics [di-op′triks] the science of refracted light.

• dinitrotoluidine chemical compounds used as insecticides and herbicides; toxic to fish if they pollute streams.

• Diorchis nyrocae a common cestode of ducks in the family Hymenolepididae.

• dinkum oil eucalyptus oil.

• Dioscorea a plant genus with edible root tubers in the family Dioscoreaceae. Some species are poisonous due to their content of dioscorine, an alkaloid with an action like picrotoxin. Called also yams. Includes D. communis (Tamus communis, black bryony).

• dioscorine an alkaloid in the plants of Dioscorea spp. Has an action similar to picrotoxin.

• Diospyros a plant genus in the family Ebenaceae; fruit consumption is associated with phytobezoar formation, particularly in horses. Includes D. kaki, D. virginiana. Called also Japanese persimmon.

• dioxacarb a carbamate pesticide.

• dioxathion an organophosphorus insecticide used as a spray or dip mainly against ticks. The toxic concentration is about four times the therapeutic concentration.

• dioxin [di-ok′sin] a highly toxic and teratogenic chlorinated hydrocarbon that once was a trace contaminant in the herbicide 2,4,5-T. Acute poisoning causes vomiting, abortion, and anestrus. Chronic poisoning causes liver damage, especially in dogs. Congenital defects caused include cranio-facial deformity and anasarca. It is excreted in the milk.

• dioxygenases [di″ok′sľ-j n-ā-s s] enzymes that incorporate both atoms of O₂ into one substrate. Less common than mono-oxygenases. Important example is the 15-15′-dioxygenase enzyme in the small intestine that cleaves plant carotenoids containing provitamin A activity, such as β-carotene, into retinal. This enzyme is absent from felines, such as the cat, and is the reason cats are dependent on animal sources of vitamin A.

• dip 1. plunge (vat) or spray dip installations in which insecticide solutions are applied to animals, especially cattle and sheep. 2. the dipping solutions, commonly sodium arsenite, rotenone, synthetic pyrethroids, and organophosphorus preparations, many not approved in some countries. 3. to submit animals to dipping. 4. see teat dip.

  • d. stain wool fiber stained by improper dipping procedure.

• dipalmityl lecithin a surfactant present in the lungs of most species produced by alveolar type II cells and necessary for normal respiratory function.

• dipalmitylphosphatidylcholine principal constituent of the phospholipid surfactant in the lungs, the absence of which plays a large part in the development of the acidophilic hyaline membranes that characterize the pulmonary lesions in neonatal respiratory distress syndrome in newborns.

• Dipcadi glaucum African plant in the family Liliaceae (Hyacinthaceae); included in the genus Ornithogalum by some authorities; contains an unidentified toxin that causes head pressing, aimless wandering, flexed fetlocks, posterior paresis, and diarrhea. Called also D. gracilipes, D. longibracteatum, wild or poison onion, malkop-ui.

• dipeptidase [di-pep′tľ-dās] a proteolytic enzyme occurring in the pancreatic secretion of chickens, and the intestinal brush border of mammals.

• dipeptidyl aminopeptidase IV [di-pep″tľ-d l] a digestive enzyme of the small intestine enterocytes (brush border).

• dipes having two hindlimbs.

• Dipetalonema [di-pet″ -lo-ne′m] a genus of nematodes of the superfamily Filarioidea (filarioids).

  • D. dracunculoides found in peritoneal membranes of dogs and humans.
  • D. evansi found in spermatic and pulmonary artery of camels.
  • D. gracile, D. marmosetae, D. obtusa, D. tamarinae found in the peritoneal cavity of primates.
  • D. grassii occurs in the subcutaneous tissue of dogs.
  • D. loxodontis found in the African elephant. Currently called Loxodontofilaria loxodontis.
  • D. odendhali found in the subcutaneous and intermuscular tissues of California sea lion.
  • D. perstans, D. streptocerca these species are primarily parasitic in humans, other primates serving as reservoir hosts.
  • D. reconditum see Acanthocheilonema reconditum.
  • D. spirocauda found in the right heart and pulmonary artery of seals.

• diphacinone [di-fa′s -nōn] an inandione derivative anticoagulant rodenticide, similar in effect to warfarin, but with prolonged activity. Restricted use pesticide in the US. See also pindone and warfarin.

• diphallia [di-fal′e- ] the state of diphallus.

• diphallus [di-fal′ s] a rare developmental anomaly characterized by duplication of the penis. Called also diphallic terata, diphallasparatus.

• diphasic [di-fa′zik] occurring in two phases.

• diphemanil [di-fe′m -nil] an anticholinergic drug used as the methyl sulfate to inhibit gastric motility and secretion, relieve pylorospasm, control sweating and relieve pruritus.

• diphenadione [di-fen″ -di′ōn] an indandione type anticoagulant used as a rodenticide and as a counter to vampire bat predation. Effects are similar to those of warfarin. See also pindone.

• diphenamid an amide type of preemergence herbicide with very low toxicity if used at recommended concentrations. Poisoning causes anorexia, weight loss and posterior paresis.

• diphenhydramine [di″fen-hi′dr -mēn] an antihistamine (H₁ blocker), used as the hydrochloride in treatment of allergic disorders and also for its sedative, antiemetic, antitussive, local anesthetic, and anticholinergic effects. Commonly known as Benadryl.

• diphenidol [di-fen′ľ-dōl] a muscarinic antagonist used as an antiemetic.

• diphenoxylate [di″f n-ok′s -lāt] a derivative of meperidine with little analgesic effect, but used as the hydrochloride for the management of non-specific diarrhea.

• diphenylamine [di-fen″ l-am′ēn] 1. a larvicide used in mixtures applied topically to screw-worm lesions. 2. a common contaminant in phenothiazine and may cause clotting defects after dosing with phenothiazine. 3. used in a field test for nitrate/nitrite poisoning.

• diphenylhydantoin [di-fen″ l-hi-dan′to-in] phenytoin.

• 2,3-diphosphoglycerate [di-fos′fo-glis′ r-āt] see 2,3-bisphosphoglycerate.

• diphosphonates [di-fos′f -nāts] bisphosphonates.

  D-30.

  

  Necrotizing laryngitis in calf diphtheria.

• diphosphopyridine nucleotide nicotinamide-adenine dinucleotide (NAD). One of the two growth factors released from erythrocytes during the preparation of chocolate agar. Called also V-factor.

• diphosphoric acid see pyrophosphoric acid.

• diphthamide an amino acid residue formed by post-translational modification of histidine and found in eukaryotic elongation factor 2 (eEF-2). Diphtheria toxin causes its ADP ribosylation, inactivating eEF-2 and blocking mRNA translation.

• diphtheria [dif-thēr′e- ] a human disease caused by Corynebacterium diphtheriae. There is no counterpart in animals, but the name diphtheria is used in diseases that have some clinical similarity to it.

  • avian d. see fowlpox.
  • calf d. a severe, often fatal necrosis of the pharynx and larynx in calves up to 3 months of age caused by Fusobacterium necrophorum. The disease is commonly associated with poor hygienic management, especially in the feeding of milk or milk substitutes, but some losses occur in well-managed calf units, and severe outbreaks can also occur in yearling cattle in feedlots. Characteristic clinical signs include high fever, moist painful cough, severe dyspnea, nasal discharge, pain on external palpation of the larynx, and a foul smell on the breath. See also oral necrobacillosis.

• diphtheritic [dif″the-rit′ik] pertaining to features of the human disease, diphtheria.

  • d. inflammation an adherent membrane, consisting of necrotic mucosa combined with fibrinous inflammatory exudate on the affected mucosa. Removal of the exudate reveals a hemorrhagic ulcerated surface.
  • d. membrane the membrane characteristic of diphtheritic inflammation. See also diphtheritic inflammation (above).

• diphtheroid [dif′th -roid] 1. resembling the diphtheria bacillus Corynebacterium diphtheriae. See also coryneform. 2. pseudodiphtheria.

• diphyllobothriasis [di-fil″o-both-ri′ -sis] infection with Diphyllobothrium spp.

• Diphyllobothrium [di-fil″o-both′re- m] a genus of long tapeworms in the family Diphyllobothriidae.

  • D. dalliae, D. dendriticum, D. pacificum, D. strictum, D. minus, D. ursi tapeworms of fish-eating mammals including humans.
  • D. erinacei Spirometraerinacei.
  • D. latum the broad or fish tapeworm, a species found in the small intestines of humans, dogs, cats and other fish-eating mammals.

• diphyodont [di-fi′o-dont″] having two dentitions, a deciduous and a permanent; characteristic of mammals.

• dipivefrin [di-piv′ -frin] an epinephrine prodrug that used to be used as the hydrochloride in ophthalmic drops to treat glaucoma.

• Diplarrhena Southern Australian genus of plants in the family Iridaceae; probably contains cardiac glycosides; causes hemorrhagic diarrhea. Includes D. moraea, D. latifolia. Called also Diplarrena, butterfly flag, native lily.

• diplegia [di-ple′je- ] paralysis of like parts on either side of the body.

• diplobacillus [dip″lo-b -sil′ s] a short, rod-shaped organism occurring in pairs; diplobacterium.

• diplobacterium [dip″lo-bak-tēr′e- m] see diplobacillus.

• diploblastic [dip″lo-blas′tik] having two germ layers.

• diplocardia [dip″lo-kahr′de- ] a condition in which the heart appears to be partly divided by a central fissure.

• Diplococcus [dip″lo-kok′ s] former name for a genus of bacteria (family Streptococcaceae). The species have been assigned other names. See Streptococcus pneumoniae.

• diplococcus [dip″lo-kok′ s] pl. diplococci Any of the spherical bacteria occurring usually in pairs as a result of incomplete separation after cell division in a single plane.

• diplocoria double pupil.

• Diplocyclos palmatus African vine in the plant family Cucurbitaceae; may contain cucurbitacins; causes severe diarrhea. Called also Bryonopsis laciniosa.

• Diplodia maydis [dip-lo′de- ] previously D. zeae; see Stenocarpella maydis.

• diplodiosis [dip″lo-de-o′sis] poisoning caused by Stenocarpella maydis, previously called Diplodia maydis.

• diploë [dip′lo-e] the spongy layer between the inner and outer compact layers of the flat bones of the skull.

• diplogenesis [dip″lo-jen′ -sis] the production of a conjoined twins.

• Diplogonoporus [dip″lo-go-nop′ -r s] a genus of tapeworms in the family Diphyllobothriidae. Now a synonym of Diphyllobothrium.

• diploid [dip′loid] 1. having a pair of each chromosome characteristic of a species, i.e., genomes in which chromosomes occur in pairs. 2. a diploid individual or cell.

  • human d. cell vaccine see human diploid cell vaccine.
  • d. karyotype a karyotype consisting of chromosomes in pairs.

• diploidy [dip′loi-de] the state of being diploid.

• Diplolophium africanum an African plant in the family Apiaceae; contains an unidentified toxin and, if ingested in large quantities when it is green, causes dyspnea, salivation, abdominal pain, staggering, and death.

• diplomyelia [dip″lo-mi-e′le- ] lengthwise fissure and seeming doubleness of the spinal cord.

• diplonema [dip″lo-ne′m ] the double chromosomes in the diplotene stage.

• diploneural [dip″lo-noor′ l] having a double nerve supply.

• diplopia [dľ-plo′pe- ] seeing two images; double vision.

• Diplopoda [di-plop′o-d ] see Myriapoda.

• Diplopylidium [dip″lo-pi-lid′e- m] a genus of tapeworms found in dogs and cats. Belongs to the family Dipylidiidae.

• diplosomatia [dip″lo-so-ma′she- ] a condition in which complete twins are joined at some of their body parts.

• diplosomia [dip″lo-so′me- ] symmetrical conjoined twins.

• Diplostomum a genus of digenetic trematodes of the family Diplostomatidae.

  • D. spathaceum found in the intestines of gulls. The metacercaria is a cause of cataracts in fish and heavy infestations may cause severe mortalities.

• diplotene [dip′lo-tēn] the stage of the first meiotic prophase, following the pachytene, in which the two chromosomes in each bivalent begin to repel one another and a split occurs between the chromosomes.

• Diplozoon a large genus of monogean trematode parasites in the family Diplozooidae.

  • D. barbi, D. paradoxus found on the gills of freshwater fish. They cause damage to the gills and predispose to bacterial infection.

• Dipnoi see lungfish.

• dipole [di′pōl] 1. a molecule having charges of equal and opposite sign. 2. a pair of electric charges or magnetic poles separated by a short distance.

• dipped back conformation in an animal in which the normal dip between withers and croup is exaggerated. Called also swayback.

• dipping [dip′ing] application of insecticide in large volume, dilute solution over the entire body for the purpose of controlling external parasites. It may be done in a plunge bath where the animal is totally immersed and must swim to the other end, or by spray dip where the animal passes through a battery of sprays that apply spray under pressure from every direction. Local application of insecticide for local effect is also carried out by jetting, and general effects are also obtained by insecticides applied as pour-ons. See also dip, teat dipping.

  • d. cage the beasts are put into the cage one at a time and lowered into a small vat of insecticide.
  • d. vat a deep, long trough that is filled with insecticide and the animals are forced to swim through it. Called also plunge dip.

• diprenorphine an opioid antagonist used principally to reverse the effects of etorphine in captured wild animals. The reversal is complete and very quick. Called also M50-50 or Revivon.

• diprophylline a theophylline derivative used as a bronchodilator. Called also dyphylline.

• diprosopus [di-pros′o-p s] a fetus with varying degrees of duplication of the face.

• dipsotherapy [dip″so-ther′ -pe] the therapeutic limitation of the amounts of fluids ingested.

• dipsticks [dip′stiks] absorbent paper strips impregnated with reagents for testing urine or other fluid for their content of electrolytes, other solutes, and blood. The container is usually provided with a color matching scale so that a rough quantitative estimation can be made.

  D-31.

  

  Reagent strip test container and combination dipstick strip.

• Diptera [dip′t r-] an order of insects with two wings, including flies, gnats and mosquitoes.

• dipterous [dip′t r- s] 1. having two wings. 2. pertaining to insects of the order Diptera.

• dipygus [di-pi′g s] a fetus with a double pelvis.

• dipylidiasis [dip″ -lľ-di′ -sis] infection with Dipylidium caninum.

• Dipylidium [dip″ -lid′e- m] a genus of tapeworms of the family Dipylidiidae.

  • D. caninum the dog tapeworm, parasitic in dogs and cats and occasionally found in humans. Esthetically unattractive when excreted in the feces, but causes little damage other than anal irritation. Fleas and lice are intermediate hosts. Called also cucumber seed tapeworm because of the appearance of proglottids on fresh canine feces.

• dipyridamole [di″pľ-rid′ -mōl] a coronary vasodilator with antiplatelet activity.

• dipyridyl compounds highly toxic herbicides. See diquat, paraquat.

• dipyrone [di′pi-rōn] a nonsteroidal anti-inflammatory drug used as an analgesic, antispasmodic antipyretic and anti-inflammatory in horses and dogs. Can result in suppression of bone marrow causing aplastic anemia and agranulocytosis with prolonged use in some species (cats) and teratogenicity. Banned for use in humans in many countries. Known also as metamizole.

  D-32.

  

  Dipylidium caninum in the intestine of a dog at necropsy.

• diquat a hormone weedkiller that may poison animals, particularly those grazing pasture contaminated by the agent. Lesions in fatal cases include pulmonary emphysema, enteritis, abomasitis and hepatic, renal, and myocardial degeneration. Clinical signs include diarrhea and a high mortality rate.

• direction orientation within the body.

  • caudal d. toward the tail end of the body.
  • cranial d. toward the head end of the body.
  • distal d. distant from the long axis of the body.
  • dorsal d. 1. the surface directed toward the back or spine. 2. the extensor surface of the distal limbs.
  • lateral d. the surface directed away from the median plane.
  • medial d. toward the median plane (a vertical plane passing through the body from nose tip to tail tip).
  • palmar d. the flexor aspect of the foot, below the carpus, the surface directed toward the ground.
  • plantar d. below the tarsus, the surface directed toward the ground.
  • proximal d. closer to the long axis of the body.
  • rostral d. toward the head or mouth.
  • ventral d. the surface directed toward the belly or ground.

• director a long, slender, grooved instrument for guiding a knife or other surgical instrument.

• dirlotapide a novel microsomal triglyceride transfer protein inhibitor that causes reduced intestinal lipid absorption and appetite suppression; used for pharmacological treatment of obesity in humans and dogs.

• Dirofilaria [di″ro-fľ-lar′e- ] a genus of nematode parasites of the superfamily Filarioidea.

  • D. acutiuscula causes swelling in the subcutaneous fascia of the dorsolumbar area of the peccary.
  • D. conjunctivae a zoonotic infection on the eyelids of humans, due to infestation of wildlife.
  • D. corynodes occurs in monkeys.
  • D. immitis occurs in cat, dog, fox and wolf and has been recorded in humans and many other species. Transmitted by the intermediate hosts, Culex, Aedes, Anopheles and other mosquito genera. Found in the blood vessels, especially the heart and the pulmonary artery. Causes heartworm disease.
  • D. repens occurs in the subcutaneous tissues of the dog and cat, and occasionally humans.
  • D. roemeri see Pelecitus roemeri.
  • D. striata found in the bobcat.
  • D. tenuis found in subcutaneous tissues of raccoons and humans.
  • D. ursi occurs in black bears.

• dirofilariasis [di″ro-fil″ -ri′ -sis] infection with nematodes of the genus Dirofilaria. Includes subcutaneous swellings. See also heartworm disease.

• dirty face syndrome see idiopathic facial dermatitis of Persian and Himalayan cats.

• dirty mare syndrome the vaginal discharge seen in nonspecific (endo) metritis in the mare, which may be caused by a number of bacteria and opportunist fungi.

• dirty tail disease ascending urinary tract disease of koalas, caused by Chlamydia pecorum.

• dis- word element. [L.] reversal, separation. [Gr.] duplication.

• disability [dis″ -bil′ľ-te] 1. inability to function normally, physically or mentally; incapacity. 2. anything that causes disability.

• disaccharidase [di-sak′ -ri-dās″] any of a group of enzymes that are components of the brush border of the intestinal epithelium and that hydrolyze disaccharides to monosaccharides.

• disaccharide [di-sak′ -rīd] any of a class of sugars each molecule of which yields two molecules of monosaccharide on hydrolysis.

• disarming [dis-ahrm′ing] various methods of minimizing the risk of bites for personnel and other animals by nonhuman primates; most commonly, it involves crown reduction of the canine teeth, followed by root canal therapy. Not recommended for vicious dogs because it will not alter their behavior and could give their owners a false sense of security.

• disarticulation [dis″ahr-tik″u-la′sh n] amputation or separation at a joint.

• disaster medicine the practice of veterinary medicine under circumstances resulting from natural disasters. Appropriate planning usually includes provisions for emergency treatment of animal injuries, control of and temporary housing of displaced animals, reuniting lost animals with their owners, and contributions to management of public health.

• disbudding [dis-bud′ing] removal of the immature horns in young ruminants. This is a much simpler and less traumatic operation than removal of the adult horns and is usually done without an anesthetic. The usual technique is a dehorning tube or set of scoops. A hot iron has some exponents. See dehorning.

• disc [disk] an alternative spelling of disk.

  • embryonic d. a flattish area in a cleaved ovum in which the first traces of the embryo are seen. Called also germinal disk.
  • germinal d. the embryo in a hen egg.
  • olfactory d. these develop on the ventrolateral aspects of the head early in fetal development. They deepen, are surrounded by the developing nasal processes, then break through into the oral cavity and become the nasal cavities.

• discard time period following the cessation of the use of a drug that a food product, such as milk, must be discarded and not used for human consumption.

• discharge [dis′chahrj] 1. a setting free, or liberation. 2. material or force set free. 3. an excretion or substance evacuated.

  • ocular d. overflow of liquid from the ocular surface over typically the lower eyelid. May be serous, mucoid, sanguineous, or purulent in nature, or some combination of the four. Indicates either excess production, reduced drainage, or both, of one of these fluids. As with other regions, the nature of the discharge can give some indication of likely cause and chronicity, but ocular discharge is seen with the majority of ocular diseases.

• discission [dľ-sizh′ n] incision, or cutting into, as of a soft cataract.

  • d.-aspiration a surgical technique for removal of soft cataracts in which abnormal lens material is broken into small pieces and removed by aspiration. Similar to phacofragmentation.

• disc(o)- word element. [L.] relationship to a disc, or disc-shaped. See also words beginning disk(o)-.

• Discocotyle a genus of monogenetic trematode parasites of the family Discocotylidae.

  • D. sagittata a significant parasite of fish, causing serious mortalities due to damage to the gills.

• discocyte [dis′ko-sīt] a discoid-shaped red blood cell, seen normally in dogs.

• discogenic caused by derangement of an intervertebral disk.

• discoid [dis′koid] 1. disk-shaped. 2. a disk-like medicated tablet.

  • d. lupus erythematosus see lupus erythematosus.
  • d. meniscus an abnormality of the meniscus (usually the lateral one), in the stifle joint, reported in dogs. Instead of being semilunar in shape it is discoid; the frequency, clinical significance, and cause are unclear.

• discontinuous variable [dis″k n-tin′u- s] see discrete variable.

• discoplacenta a disc-shaped placenta, found in primates and rodents.

• discordance [dis-kor′d ns] the occurrence of a given trait in only one member of a twin pair.

• discreditable conduct conduct by a professional person that is likely to bring sufficient discredit to the profession generally that the public’s confidence in it is reduced. Penalties imposed by the registering authority may be as severe as deregistration.

  D-33.

  

  Vaginal discharge from a mare with placentitis.

• discrete [dis-krēt′] made up of separated parts; characterized by lesions that do not become blended.

• discretizing measurements modification of measurement data (e.g., body weight to the nearest kilogram) to make classification into discrete groups possible.

• discus [dis′k s] pl. disci [L.] 1. see disk. 2. a popular aquarium fish in the genus Symphysodon spp. It is compressed, round and brightly colored.

  • d. oophorus see cumulus oophorus.
  • d. ovigerus see cumulus oophorus.
  • d. proligerus see cumulus oophorus.

• disease [dľ-zēz′] traditionally defined as a finite abnormality of structure or function with an identifiable pathological or clinicopathological basis, and with a recognizable syndrome or constellation of clinical signs. This definition has long since been widened to embrace subclinical diseases in which there is no tangible clinical syndrome but that are identifiable by chemical, hematological, biophysical, microbiological, or immunological means. The definition is used even more widely to include failure to produce at expected levels in the presence of normal levels of nutritional supply and environmental quality. For specific diseases, see under the specific name, e.g., Aujeszsky’s disease, Bang’s disease, foot-and-mouth disease.

  • air-borne d. the causative agent is transmitted via the air without the need for intervention by other medium. See also wind-borne disease.
  • atypical d. a form of a disease that differs significantly in clinical signs or pathological lesions from classical or textbook forms of the disease, e.g., bovine atypical interstitial pneumonia.
  • d. carrier see carrier, vector.
  • clinical d. see clinical (3).
  • d. cluster a group of animals with the same disease occurs at an unusual level of prevalence for the population as a whole. The cluster may be in space, with high concentrations in particular localities, or in time, with high concentrations in particular seasons or in particular years.
  • communicable d. infectious disease in which the causative agents may pass or be carried from one animal to another directly or indirectly on inanimate objects or via vectors.
  • complicating d. one that occurs in the course of some other disease as a complication.
  • constitutional d. one involving a system of organs or one with widespread signs.
  • contagious d. see communicable disease (above).
  • d. control reducing the prevalence of a disease in a population, including eradication, by chemical, pharmaceutical, quarantine, management including culling, or other means or combinations of means.
  • d. control programs at the national or regional level, organized routines specifying agents, control strategies, administration, time and personnel allocations, community support, funding, participation of corporate or government agencies, animal and animal product disposal.
  • deficiency d. a condition due to dietary or metabolic deficiency, including all diseases caused by an insufficient supply of essential nutrients.
  • demyelinating d. any condition characterized by destruction of myelin.
  • domestic d. indigenous to the country.
  • egg-borne d. an infectious disease of birds in which the agent is spread via the egg.
  • emerging d’s. diseases that are emerging or exploding in any area of the world, either as de novo diseases or ones whose boundaries are expanding. Examples would be Ebola virus and West Nile virus. Followed by an emerging number of veterinary, medical and microbiological journals. The emergence of human, plant, and animal diseases is the focus of the Federation of American Scientists and the internet web site of the International Society for Infectious Diseases, ProMED-mail (www.promedmail.org).
  • endemic d. see endemic.
  • environmental d. control control by changing the environment, e.g., draining a swamp, ventilating a barn.
  • epidemic d. see epidemic.
  • etiological d. classification diseases arranged in the order of their etiological agents, e.g., bacterial, mycoplasma.
  • exotic d. a disease that does not occur in the subject country. Said of infectious diseases that may be introduced, e.g., rabies is exotic to the UK, contagious bovine pleuropneumonia is exotic to the US.
  • focal d. a localized disease.
  • d. forecasting the monitoring of specific biological and environmental risk factors to predict the risk that a disease will occur or that its intensity will increase. An example would be the use of climatic data to predict the risk for fascioliasis in sheep and cattle.
  • foreign animal d, diseases that are not known to exist in the US; called also exotic diseases.
  • fulminant d. an explosive outbreak in a group or a rapidly developing, peracute development of a disease in an individual. Called also fulminating.
  • functional d. any disease involving body functions but not associated with detectable organic lesion or change.
  • generalized d. one involving all or many body systems; often said of infectious diseases in which there is spread via the bloodstream. See also systemic disease (below).
  • glycogen d. any of a group of genetically determined disorders of glycogen metabolism, marked by abnormal storage of glycogen in the body tissues. See also glycogen storage disease.
  • heavy chain d. see heavy-chain disease.
  • hemolytic d. of newborn see alloimmune hemolytic disease of the newborn.
  • hemorrhagic d. of newborn see neonatal hemorrhagic disease.
  • d. history that part of a patient’s history which relates only to the disease from which the patient is suffering.
  • holoendemic d. most animals in the population are affected.
  • hyperendemic d. the rate of infection is steady, but high.
  • hypoendemic d. the rate of infection is steady and only a few animals are infected.
  • immune complex d. see immune complex disease.
  • infectious d. one caused by small living organisms including viruses, bacteria, fungi, protozoa and metazoan parasites. It may be contagious in origin, result from nosocomial infections or be due to endogenous microflora of the nose and throat, skin, or bowel. See also communicable disease (above).
  • manifestational d. classification diseases arranged in the order of their clinical signs, epidemiological characteristics, necropsy lesions, e.g., sudden death diseases.
  • mesoendemic d. the disease occurs at an even rate and a moderate proportion of animals are infected.
  • metabolic d. see metabolic diseases.
  • molecular d. any disease in which the pathogenesis can be traced to a single, precise chemical alteration, usually of a protein, which is either abnormal in structure or present in reduced amounts. The corresponding defect in the DNA coding for the protein may also be known.
  • multicausal d. 1. a number of causative agents are needed to combine to cause the disease. 2. the same disease can be caused by a number of different agents.
  • multifactorial d. see multicausal disease (above).
  • new d. disease not previously recorded. May be variants on an existing disease, e.g., infectious bovine rhinotracheitis, or escapes from other species, e.g., the Marburg virus disease of humans.
  • notifiable d. a disease of which any occurrence is required by law to be notified to government authorities, see reportable disease, scheduled disease.
  • occupational d. one caused by exposure to substances or agents at the workplace.
  • organic d. due to or accompanied by structural changes.
  • pandemic d. a very widespread epidemic involving several countries or an entire continent.
  • quarantinable d. a disease that the law requires to be restricted in its spread by putting the affected animals, farms or properties on which it occurs in quarantine.
  • reportable d. see reportable disease.
  • d. reservoir any animal or fomite in which an infectious disease agent is preserved in a viable state or multiplies and upon which it may depend for survival.
  • scheduled d see scheduled diseases.
  • secondary d. 1. a disease subsequent to or a consequence of another disease or condition. 2. a condition due to introduction of incompatible, immunologically competent cells into a host rendered incapable of rejecting them by heavy exposure to ionizing radiation.
  • self-limited d. see self-limited.
  • sex-limited d. disease limited in its occurrence to one or other sex. See also sex-linked.
  • sexually transmitted d. (STD) a disease that can be acquired by sexual intercourse.
  • slaughter d. control see slaughter (2).
  • sporadic d. occurring singly and haphazardly; widely scattered; not epidemic or endemic. See also sporadic bovine encephalomyelitis, sporadic leukosis, sporadic lymphangitis.
  • storage d. see storage disease.
  • d. syndrome see syndrome.
  • systemic d. sufficiently widespread in the body to cause clinical signs referable to any organ or system, and in which localization of infection may occur in any organ.
  • transboundary animal d. highly contagious animal diseases that have the potential to spread very rapidly irrespective of national borders. Examples are rinderpest and foot and mouth disease.
  • d. triangle interaction between the host, the disease agent, and the environment.
  • vector-borne d. one in which the pathogenic microorganism is transmitted from an infected individual to another individual by an arthropod or other agent, sometimes with other animals serving as intermediary hosts. Vector-borne infectious diseases are emerging or resurging as a result of factors such as insecticide and drug resistance and climate change.
  • d. wastage loss of income generated by production of milk, eggs, fiber, or loss of capital value because of diminution in the patient’s value.
  • wasting d. any disease marked especially by progressive emaciation and weakness.
  • zoonotic d. disease capable of spread from animals to humans. See also zoonosis.

• disease-free animals a term for animals born and reared in an uncontaminated environment from uninfected parents and guaranteed to be free of infection. More guarded titles are usual, e.g., hysterectomy produced, artificially reared, specific pathogen free.

• disengagement [dis″ n-gāj′m nt] emergence of the fetus, or part thereof, from the vaginal canal.

• disequilibrium [dis-e″kwľ-lib′re- m] unstable with respect to equilibrium.

• dish development [dish] development of radiographic film in the simplest equipment, developing trays.

• dished face less than normal growth of the facial bones so that the lateral silhouette of the face is depressed. Called also stag face.

• dishing [dish′ing] a fault in a horse’s gait in which one or both forefeet is thrown outward when moving forward.

• dishorning [dis-horn′ing] an older surgical term for dehorning.

• disinfect [dis″in-fekt′] to free from pathogenic organism, or to render the potential pathogens inert.

• disinfectant [dis″in-fek′t nt] a chemical agent that destroys infective agents. Usually applied to inanimate objects as they are too toxic to be used on living tissues. Disinfectants may vary in their efficacy against different infectious agents and also in their activity in the presence of organic matter.

• disinfection [dis″in-fek′sh n] the act of disinfecting.

  • terminal d. disinfection of a loose box or cage and its contents at the termination of a disease.
  • d. time the time required for a disinfectant to achieve its maximum effect. It is influenced by the material being disinfected, the agent’s targets and potency of the disinfectant.

• disinfestants see insecticide.

• disinfestation [dis″in-f s-ta′sh n] destruction of insects, rodents or other animal forms present on the animal or its harness or in its surroundings, and that may transmit disease.

• disintegrant [dis-in′t -gr nt] an agent used in pharmaceutical preparation of tablets, which causes them to disintegrate and release their medicinal substances on contact with moisture.

• disjunction [dis-junk′sh n] the act or state of being disjoined. In genetics, the moving apart of bivalent chromosomes at the first anaphase of meiosis.

• disk [disk] a circular or rounded flat plate. See also disc, intervertebral disk.

  • articular d. a pad of fibrocartilage or dense fibrous tissue present in some synovial joints such as that between the ulna and the carpus of carnivores and primates. As specialized intra-articular structures, they differ from articular plates in that they have nerve and blood supplies.
  • choked d. papilledema.
  • d. explosion the lesion produced by a sudden extrusion of non-degenerate nucleus pulposus from intervertebral disks into the cervical vertebral canal as a result of trauma.
  • intra-articular d. articular disk.
  • optic d. the optic nerve head or that part of the optic nerve visible funduscopically where nerve fibers running from the brain turn approximately at right angles to spread over the retina.
  • slipped d. the popular name for prolapse of the nucleus of an intervertebral disk.

• disk-diffusion test see antimicrobial sensitivity test.

• diskectomy [dis-kek′t -me] excision of an intervertebral disk.

• diskiform in the shape of a disk.

• diskitis [dis-ki′tis] inflammation of a disk, especially of an intervertebral disk.

• diskogenic discogenic.

• diskography [dis-kog′r -fe] radiography of the vertebral column after injection of radiopaque material into an intervertebral disk.

• diskolysis lysis of an intervertebral disk. See also intervertebral disk disease.

• diskospondylitis [dis″ko-spon-d -li′tis] a destructive, inflammatory and proliferative process involving intervertebral disks, their associated endplates and vertebral bodies; best described in pigs and dogs.

• dislocation [dis″lo-ka′sh n] 1. displacement of a bone from a joint. Signs include loss of motion, temporary paralysis of the involved joint, pain and swelling, and sometimes shock. Some dislocations, especially of the hip, are congenital, usually resulting from a faulty construction of the joint. 2. displacement of the lens in the eye. See lens luxation.

  • complete d. one in which the surfaces are entirely separated.
  • compound d. one in which the joint communicates with the outside air through a wound. More commonly referred to as an open dislocation.
  • pathological d. one due to disease of the joint or to paralysis of the muscles.
  • simple d. one in which there is no communication with the air through a wound.

• dismemberment [dis-mem′b r-m nt] amputation of a limb or a portion of it.

• dismutase any of a group of enzymes that have the ability to catalyze the reaction of two molecules of the same compound to yield two molecules in different oxidation states.

• disodium EDTA [di-so′de- m] see edetate.

• disomus [di-so′m s] synencephaly.

• disophenol (DNP) an injectable anthelmintic for hookworms in cats and dogs and Haemonchus contortus in sheep. Larger than normal doses cause somnolence, prostration and sometimes death. Transient cataract is also recorded as a toxic sequel. See also nitrophenol.

• disoprofol see propofol.

• disopyramide [di″so-pir′ -mīd] an oral antiarrhythmic agent, a class Ia (fast sodium channel blocker) anti-arrhythmic that prolongs the action potential and can have negative inotropic effects.

• disorder [dis-or′d r] a derangement or abnormality of function. Used as a euphemism when it is not certain that the abnormality is in fact a disease, or when public relations suggest that the word disease is likely to be inflammatory or upsetting.

• disorganization [dis-or″g n-ľ-za′sh n] the process of destruction of any organic tissue; any profound change in the tissues of an organ or structure which causes the loss of most or all of its proper characters.

• disorientation [dis-or″e- n-ta′sh n] the patient appears to suffer a loss of proper bearings, or a state of mental confusion as to time, place, or identity.

  • cetacean d. see stranding.

• dispensary [dis-pen′s -re] any place where drugs or medicines are stored and dispensed.

• dispensatory [dis-pen′s -tor-e] a book that describes medicines and their preparation and uses.

• D. of the United States of America a collection of monographs on unofficial drugs and drugs recognized by the Pharmacopeia of the United States (USP), the Pharmacopoeia of Great Britain, and the National Formulary (NF), also on general tests, processes, reagents, and solutions of the USP and NF, as well as drugs used in veterinary medicine.

• dispensing [dis-pen′sing] provision of drugs or medicines as set out properly on a lawful prescription. A prescription can only be filled, the drugs supplied, by a registered pharmacist, veterinarian, dentist, or member of the medical profession. The law requires that a prescription be written only for patients that are in the veterinarian’s care. Provision of drugs or medicines as set out properly on a lawful prescription.

• dispermy [di′sp r-me] the fertilization of one egg by two sperm.

• dispersal sale sale of an entire herd or flock; implies that the breeder is not retaining breeding animals and that the purchaser will now have the advantage of controlling that genotype.

• disperse [dis-p rs′] to scatter the component parts, as of a tumor or the fine particles in a colloid system; also, the particles so dispersed.

• dispersion [dis-pur′zh n] 1. the act of scattering or separating; the condition of being scattered. 2. the incorporation of one substance into another. 3. a colloid solution.

• Dispharynx see Synhimantus.

• displaced see displacement.

• displacement [dis-plās′m nt] removal to an abnormal location or position.

  • d. of abomasum see left, right abomasal displacement.
  • fracture d. the movement of fractured bone fragments away from their relatively normal alignment.
  • inherited d. of molar teeth see inherited displacement of molar² teeth.
  • left dorsal colon d. see left colon displacement.
  • liver d. see liver displacement.

• display work station in digital radiology, the computer, image software and monitor to enable the display and adjustment of digital images.

• disposition [dis″p -zīsh′ n] setting in place.

  • d. curve the graphic representation of changes in the blood concentration of a drug after administration.
  • drug d. delivering a drug into its appropriate location in the body and in an appropriate concentration.

• disproportion [dis″pro-por′sh n] a lack of the proper relationship between two elements or factors.

  • fetopelvic d. abnormally large size of the fetus in relation to the maternal pelvis (fetomaternal dysproportion), leading to difficulties in delivery.

• dissect [di-sekt′] to cut apart, or separate; especially, the exposure of structures of a cadaver for anatomical study.

• dissection [dľ-sek′sh n] 1. the act of dissecting. 2. a part or whole of an organism prepared by dissecting. 3. passage of blood between layers of the wall of a blood vessel.

  • blunt d. separation of tissues along natural lines of cleavage, by means of a blunt instrument or finger.
  • sharp d. separation of tissues by means of the sharp edge of a knife or scalpel, or with scissors.
  • water beam d. the use of a high-pressure jet of saline to remove parenchymal cells, retaining more resistant structures such as ducts, capsule and vessels.

• disseminated [dľ-sem′ľ-nāt″ d] scattered; distributed over a considerable area.

• Disse’s space small lymph-carrying spaces between the liver sinusoids and hepatocytes.

• dissociation [dľ-so″se-a′sh n] the act of separating or the state of being separated.

  • atrial d. independent beating of the left and right atria, each with normal rhythm or with various combinations of normal rhythm, atrial flutter, or atrial fibrillation.
  • atrioventricular d. independent pacemakers in the atria and ventricles with result that atrial depolarization does not reliably precede and cause ventricular depolarization.
  • electromechanical d. normal cardiac electrical activity is detected on surface ECG but there is no concomitant mechanical activity (contraction) in the heart.
  • hepatocyte d. hepatocytes becomes detached from their neighboring cells, either generally or locally.

• dissolution [dis″o-loo′sh n] 1. the process in which one substance is dissolved in another. 2. separation of a compound into its components by chemical action. 3. liquefaction. 4. death.

• dissolve [dľ-zolv′] 1. to cause a substance to pass into solution. 2. to pass into solution.

• distad [dis′tad] in a distal direction.

• distaff the female line in the pedigree of an animal.

• distal [dis′t l] remote; farther from any point of reference. See also direction.

  • d. convoluted tubule the part of the renal tubular system interposed between the nephron loop and the arched collecting tubule. See also convoluted tubules.
  • d. interphalangeal joints see Table 10.
  • d. phalanx the third phalanx of digits with three bones, but the terminal phalanx of digits which contain more than three bones such as those of cetacean flippers and avian toes.
  • d. sesamoid navicular bone in the horse.
  • d. tarsal bones the tarsal bones that abut against the metatarsals.

• distance [dis′t ns] the measure of space intervening between two objects or two points of reference.

  • critical d. see flight distance (below).
  • flight d. the distance that agricultural and wild animals like to keep between themselves and a threat of danger. The distance varies with the degree of wildness of the animals and the circumstances. Called also the circle of safety, critical, fright, or guard distance. Important in planning animal handling facilities, yards, zoos, and the like. Neglect of the need to provide adequate space in which an animal can escape will lead to them damaging themselves by running into fences.
  • guard d. see flight distance (above).
  • interocclusal d. the distance between the occlusal surfaces of the maxillary and mandibular teeth with the mandible in physiological rest position.
  • interocular d. the distance between the eyes, usually used in reference to the interpupillary distance (the distance between the two pupils when the visual axes are parallel).
  • social d. average distance between animals in a community. An expression of the concentration of the animals in the environment.

• distemper [dis-tem′p r] a name for several infectious diseases of animals.

  • avian d. see Newcastle disease.
  • canine d. an acute viral disease of dogs caused by a morbillivirus; characterized by high morbidity and high mortality, ocular and nasal discharge, vomiting, diarrhea, coughing, dyspnea, and various progressive neurologic signs. In addition, some dogs develop ‘hard pads’ (hyperkeratosis of the footpads), persistent muscle twitches (myoclonus), optic neuritis, and later retinal atrophy, enamel hypoplasia (distemper teeth—see below), or a chronic encephalitis. Interstitial pneumonia and demyelinating encephalomyelitis are common pathological features. Also occurs in other Canidae as well as Procyonidae, Ursidae, Mustelidae and Hyaenidae. The disease can be prevented by vaccination at a young age. Called also Carré’s disease.
  • equine d. see strangles.
  • feline d. see feline panleukopenia.
  • phocine d. a disease first observed in European harbor seals in 1988 caused by a morbillivirus; clinical signs are similar to those of canine distemper.
  • d. teeth the pitted, discolored teeth that may result when young dogs are infected with distemper virus prior to the eruption of their permanent teeth. Other insults to enamel formation at this age may also be responsible for this defect.

• distention [dis-ten′sh n] the state of being distended, or stretched out or enlarged; the act of distending. For individual local distentions, see the location, e.g., abomasal distention.

• distichia [dis-tik′e- ] aberrant eyelashes (cilia) formed from follicles within the Meibomian gland so as to emerge through the gland openings at the eyelid margin and therefore usually touching and irritating the corneal surface.

• distichiasis [dis″tľ-ki′ -sis] having distichia; can be clinically irrelevant or cause varying degrees of keratoconjunctival irritation or ulceration.

• distillate [dis′til-āt] a product of distillation.

• distillation [dis″tľ-la′sh n] vaporization; the process of vaporizing and condensing a substance to purify the substance or to separate a volatile substance from less volatile substances.

  • fractional d. separation of volatilizable substances into a number of fractions, based on their different boiling points.

• distiller’s pertaining to the by-products of the distillation of spirits.

  • d. grains one of the residues of fermentation for the production of spirits. Contains most of the protein of the original grain and is an excellent supplement to diets of heavy milking cows.
  • d. solubles the dehydrated thin stillage from whisky manufacture. Contains a high concentration of B vitamins.

• distobuccal [dis″to-buk′ l] pertaining to or formed by the distal and buccal surfaces of a tooth.

• distoclusion [dis″to-kloo′zh n] a skeletal malocclusion, relating to the length of the lower jaw (i.e., mandibular distoclusion, also called class 2 malocclusion: abnormal rostrocaudal relationship between the dental arches in which the lower dental arch occludes caudal to its normal position relative to the upper dental arch).

• distomatosis [dis″to-m -to′sis] see fascioliasis.

  D-34.

  

  Distemper teeth.

  D-35.

  

  Distichiasis.

• distomiasis [dis″to-mi′ -sis] infection due to trematodes or flukes. See also fascioliasis.

• Distomum hepaticum see Fasciola hepatica.

• distortion [dis-tor′sh n] the state of being twisted out of normal shape or position.

• distoversion a dental malocclusion in which a tooth that is in its anatomically correct position in the dental arch, but that is abnormally angled in a distal direction.

• distraction [dis-trak′sh n] 1. diversion of attention. 2. separation of joint surfaces without rupture of their binding ligaments and without displacement. 3. surgical separation of the two parts of a bone after it is transected.

  • d. index a measure of hip laxity calculated by obtaining the laxity index and distraction index from a series of pelvic radiographs of a dog. A unitless number from 0 to 1, with higher numbers reflecting greater laxity. See also PennHIP.
  • d. osteogenesis the development of new bone growth in an area subjected to gradual tension stress by the deliberate separation of fragments by traction.

• distress [dis-tres′] physical or mental anguish or suffering.

  • r. distress labored breathing suggestive of air hunger. Ineffective respiration.

• distribution [dis″trľ-bu′sh n] the arrangement of numerical data. The arrangement may be in accordance with magnitude, a frequency distribution, or in relation to geographical location, a spatial distribution.

  • age d. see age distribution.
  • bimodal d. the distribution has two regions of high frequency of observations separated by a zone of low frequency.
  • binomial d. a probability distribution associated with two mutually exclusive outcomes.
  • cluster d. a nonrandom distribution with observations aggregating about geographic or temporal variables. May be deceptive and merely reflect the distribution of an uneven population.
  • frequency d. a table or graph of the frequency of occurrence of each value of a variable.
  • Gaussian d. see normal distribution (below).
  • hypergeometric d. may apply to sampling without replacement of a finite population.
  • lognormal d. a distribution that is normal when the log values of the variable are considered.
  • normal d. a graph of the distribution appears as a bell-shaped curve which is symmetrical on the two sides of the vertical axis through the peak of the curve. Called also gaussian distribution.
  • parent d. the distribution (population) that was originally sampled.
  • Poisson d. see Poisson distribution.
  • regular d. distributed at regular intervals of time or space; all values within its given interval are equally likely.
  • sex d. an increase in frequency in one sex, which includes neutered males and neutered females. Called also sex-linked or sex-associated.
  • skewed d. a distribution in which the curve illustrating it is not symmetrical but has a long tail on one or other side of the graph.
  • spatial d. variations in distribution related to position in space, e.g., close to the door of a barn.
  • t-d. see t-test.
  • temporal d. variation in distribution related to time, e.g., occurrence of disease incidents after visits by veterinarians, inseminators, feed salesmen.

• distributive circulatory failure see vasogenic shock.

• disturbance [dis-tur′b ns] a departure or divergence from that which is considered normal.

• disturbed places areas of pasture seriously impacted by livestock action such as winter-feeding areas or gateway area where normal pasture species are replaced by weeds and annual grasses.

• disulfoton an organophosphorus pesticide.

• DIT di-iodotyrosine.

• diterpene highly irritant plant diterpenoid esters, e.g., daphnane, tigliane, ingemane.

• diterpenoid alkaloid a group of complex plant chemicals with similar structure to that of a terpene. Includes well-known toxins, e.g., aconitine, barbitine, lycoctinine, delphine, heteratisine.

• dithiazanine a broad-spectrum anthelmintic and microfilaricide used for the treatment of heartworm in dogs; also used for treatment of Strongyloides and Spirocerca spp. Called also dizan.

• dithiocarbamates fungal seed dressing unlikely to be poisonous for animals.

• dithizone 1. a chelating agent used in the treatment of thallium poisoning, but has its own toxicity, causing blindness in dogs. A very sensitive test agent for small amounts of metals, e.g., lead. Also called dithizon. 2. a very sensitive test agent for small amounts of metals, e.g., lead. Called also dithizon.

• Dittrichia graveolens plant in the family Asteraceae; contains a toxic oil and causes dermatitis, diarrhea, enteritis. Called also Inula graveolens, stinkwort, cape khaki weed.

• di-ureido isobutane (DUIB) a nitrogen-rich industrial by-product, used as a feed supplement but can be poisonous to ruminants if fed in more than small amounts and in a diet deficient in carbohydrate. The toxic effect is that of ammonia poisoning as experienced with urea feeding. See also urea. Suspect also of producing dermatitis with pruritus in cattle.

• diurese [di″u-rēs′] the act of effecting diuresis.

• diuresis [di″u-re′sis] increased excretion of the urine.

  • cold d. occurs in hypothermia as a result of peripheral vasoconstriction, hyperglycemia and decreased renal tubular absorption.
  • osmotic d. due to increased concentration of solutes that are not reabsorbed in the proximal tubules and that, by osmotic pressure, cause water to be retained. See also osmotic diuretic.
  • postobstruction d. due to the diuretic effect of urea and electrolytes retained during the period of obstruction.
  • water d. ingestion and excretion of an excess of water, without a corresponding amount of sodium; involves expansion of plasma volume, increased left atrial pressure, and inhibition of ADH. See also obligatory water diuresis.

• diuretic [di″u-ret′ik] 1. increasing urine excretion or the amount of urine. 2. an agent that promotes urine secretion.

  • aldosterone antagonist d. affects tubular function by blocking the sodium retention activity of aldosterone. See also spironolactone.
  • aminouracil d’s a group of heterocyclic compounds similar to xanthines and with similar effects. See xanthine diuretics (below).
  • benzothiazide d’s drugs that exert their effect on the proximal part of the renal tubule preventing resorption of sodium. Called also thiazide diuretics. The best known members of the group are chlorothiazide and its derivatives.
  • carbonic anhydrase inhibitor d’s drugs that exert their effect on tubular resorption in the kidney by inhibiting carbonic anhydrase. These compounds are used preferentially for the treatment of chronic glaucoma because the formation of aqueous humor is highly dependent on carbonic anhydrase. See also acetazolamide.
  • loop of Henle d’s drugs that affect the resorption of sodium in the ascending loop of Henle. Called also loop diuretic. See also furosemide (frusemide) and ethacrynate sodium.
  • mercurial d. no longer used; the mode of action is to interfere with tubular enzyme systems so that tubular resorption is blocked. Overuse causes permanent renal damage.
  • osmotic d’s drugs that produce a very rapid loss of sodium and water by inhibiting their reabsorption in the kidney tubules and the loop of Henle. Mannitol is clinically the most useful of these diuretics, but it has some serious side effects, such as pulmonary edema and congestive heart failure.
  • potassium-retaining d’s drugs that appear to act directly on renal tubular function. See also triamterene.
  • xanthine d’s drugs that stimulate cardiac activity but also have a direct effect on the renal tubules. See also theophylline.

• diurnal [di-ur′n l] pertaining to or occurring during the daytime, or period of light.

• diuron a phenylurea herbicide of low toxicity but capable of poisoning animals if given in very large amounts. Causes anorexia, weight loss, and muscular weakness.

• Diutina rugosa a yeast formerly classified as Candida rugosa. Associated with mastitis in cattle.

• divalent [di-va′lent] 1. bivalent. 2. carrying an electronic charge of two units.

• divergence [di-vur′j ns] a moving apart, or inclination away from a common point.

• diverticular [di″v r-tik′u-l r] pertaining to or resembling a diverticulum.

• diverticulectomy [di″v r-tik″u-lek′t -me] excision of a diverticulum.

• diverticulitis [di″v r-tik″u-li′tis] inflammation of a diverticulum, especially inflammation involving diverticula of the intestine. Weakness of the muscles of the bowel leads to the formation of diverticula, small blind pouches lined by intestinal mucosa in the lining and wall, usually following blood vessels. Inflammation may occur as a result of collections of bacteria or other irritating agents trapped in the pouches and perforation may occur. In horses and pigs, these are associated with muscular hypertrophy of the small intestine.

  • d. and ileitis see porcine proliferative enteropathy.

• diverticulogram [di″v r-tik′u-lo-gram] a radiograph of a diverticulum.

• diverticulosis [di″v r-tik″u-lo′sis] the presence of diverticula in the absence of inflammation. See diverticulitis.

• diverticulum [di″v r-tik′u-l m] pl. diverticula [L.] a circumscribed pouch or sac occurring normally or created by herniation of the lining mucous membrane through a defect in the muscular coat of a tubular organ.

  • auditory tube d. see guttural pouch.
  • dorsal urethra d. a small pouch dorsal to the urethra in the male ruminant.
  • esophageal d. a congenital or acquired localized dilatation or outpouching of the esophageal wall in which food and liquids may accumulate. Pulsion (or pressure) diverticula result from increased intraluminal pressure and protrusion of mucosa through the muscular wall. Traction diverticula are created by periesophageal inflammation, fibrosis, and adhesions to surrounding structures. Vascular ring anomalies are a common cause of anterior thoracic esophageal diverticula in dogs. Epiphrenic are those located between the heart base and diaphragm. Clinical signs include dysphagia and regurgitation, and esophageal obstruction by impacted food may occur.
  • intestinal d. a pouch or sac formed by hernial protrusion of the mucous membrane through a defect in the muscular coat of the intestine.
  • nasal d. the part of the horse’s nostril dorsal to the alar fold leads into this blind pouch, which is lined with skin. Called also false nostril.
  • pressure d. see esophageal diverticulum (above).
  • pulsion d. see esophageal diverticulum (above).
  • rectal d. weakness and rupture of the muscular layer of the rectal wall allows formation of a pocket. Most commonly seen in dogs in association with perineal hernia. There is straining and an obvious bulge beside the anus.
  • stomach d. a small pouch at the left end of the pig’s stomach, close to the esophageal entry into the stomach.
  • suburethral d. lies below the opening of the urethra of the cow.
  • traction d. see esophageal diverticulum (above).
  • d. tubae auditivae see guttural pouch.

• diving [di′ving] the act of submerging underwater. See diving reflex.

• divulsion [dľ-vul′sh n] the act of separating or pulling apart.

• divulsor [dľ-vul′s r] an instrument for dilating a stricture in any part of the body, commonly the urethra.

• dizygotic [di″zi-got′ik] pertaining to or derived from two separate zygotes (fertilized ova); said of twins.

• dizygous [di-zi′g s] dizygotic.

• DJD degenerative joint disease, See osteoarthritis.

• dk symbol, deca-.

• DKA diabetic ketoacidosis.

• dl- chemical prefix (small capitals) denoting that the substance is an equimolecular mixture of two catamorphs, one of which corresponds in configuration to d-glyceraldehyde, the other to l-glyceraldehyde.

• dL, dl decaliter; a metric unit of volume; equals 10 L.

• D_Lco diffusing capacity of carbon monoxide across the alveolar membrane in the lung.

• D_Lo₂ diffusing capacity of the lung across the alveolar membrane.

• DLA dog leukocyte antigen.

• DLE discoid lupus erythematosus.

• DLH domestic longhair (cat).

• DM 1. dry matter. 2. abbreviation used for diabetes mellitus.

• DMI dry matter intake.

• DMAC a combination cancer chemotherapy protocol that uses dexamethasone, melphalan, actinomycin D, and cytosine arabinoside; used in the treatment of lymphoma.

• DMNA dimethylnitrosamine.

• DMP dimethyl phthalate.

• DMSA dimercaptosuccinic acid.

• DMSO dimethyl sulfoxide, an industrial solvent that has the ability to penetrate plant and animal tissues and to preserve living cells during freezing. It has bacteriostatic, anti-inflammatory, analgesic, radioprotective, fibrinolytic, and vasodilative properties, and it inhibits cholinesterase and granulation tissue. DMSO also has been used as an agent to increase the penetrability of other substances. For example, DMSO is mixed with another medication and applied topically to facilitate local delivery of the medication. It is also administered intravenously in horses with inflammatory diseases of the central nervous system to relieve inflammation and the associated increase in intracranial pressure.

• DMT dimethyltryptamine.

• DNA deoxyribonucleic acid.

  • DNA binding proteins are of two general types: histone proteins that are part of the unit structure of chromosomes called nucleosomes and nonhistone proteins that are present in small amounts and include regulatory proteins.
  • chromosomal DNA see chromosome.
  • circular DNA a DNA molecule that is a closed-ring structure, found in mitochondria, and some prokaryote chromosomes, plasmids, and viruses.
  • closed DNA complexes the first of two kinetically distinct steps required for RNA polymerase to initiate transcription in which the RNA polymerase binds electrostatically to the closed promoter complex where DNA isdouble stranded. The second step involves the isomerization of the promoter complex where the DNA is opened into a transcription bubble.
  • DNA construct a DNA molecule that has been inserted into a cloning vector.
  • copy DNA (cDNA) called also complementary DNA. See cDNA.
  • DNA deletion see deletion.
  • DNA double helix see double helix.
  • duplex DNA double-stranded DNA. See deoxyribonucleic acid.
  • end labeling DNA methods for labeling DNAwith radioisotopes or other detectable marker molecules at the ends using the terminal transferase 3′-labeling or polynucleotide kinase for 5′-labeling.
  • episomal DNA that present in a cell as extra chromosomal; exemplified by plasmids of prokaryotic cells. See plasmid.
  • eukaryotic DNA see deoxyribonucleic acid.
  • exogenous DNA the DNA that has been introduced into a host by cloning.
  • DNA fingerprint see restriction fragment length polymorphism (RFLP).
  • DNA glycosylases enzymes involved in the excision-repair mechanisms for DNA.
  • heteroduplex DNA duplex DNA with strands from different origins.
  • DNA gyrase [ji′rās] see gyrase.
  • DNA library a collection of cloned DNA molecules from a genome.
  • DNA ligase [li′gās] an enzyme that repairs breaks or nicks in the DNA backbone, for example, joining Okazaki fragments during DNA replication; essential in recombinant DNA technology for DNA cloning.
  • DNA methylome a map of cytosine methylation sites in a cell DNA that has epigenetic effects.
  • DNA microarray an ordered set of oligonucleotides immobilized on a microscope slide or other solid surface used for the detection of cognate nucleotide sequences such as the pattern of gene expression in a particular cell population by hybridization with fluorescently labeled cDNA prepared from total mRNA isolated from the cells.
  • mobile DNA a DNA sequence that can move from one location within a genome to another. Called also jumping genes or transposon. See also retrotransposon and transposable genetic elements.
  • open DNA complex a local opening of about 10 base pairs formed at the transcription initiation site following the electrostatic binding of RNA polymerase holoenzyme to the promoter region. Called also transcription bubble.
  • DNA polymerase [p -lim′ r-ās] of Escherichia coli; has three distinct enzymatic activities: (a) a 5′ to 3′ polymerase activity which, under the direction of a template DNA, catalyzes the addition of mononucleotide units, produced from deoxynucleoside 5′-triphosphates, to the 3′-hydroxyl terminus of a primer chain; (b) a 5′ to 3′ exonuclease active only on duplex DNA; (c) a 3′ to 5′ exonuclease primarily active on single-stranded DNA that can selectively remove mismatched terminal nucleotides, thus carrying out a proofreading function. Additionally, it catalyzes both the pyrophosphorolysis of DNA, a reaction that is the reverse of polymerization, and pyrophosphate exchange that represents a repetitive sequence of nucleotide addition and pyrophosphorolysis.
  • DNA probe see probe (2).
  • DNA repair a series of enzymatic mechanisms whereby errors or damage to one of the two DNA strands are removed by excision and replaced by correct nucleotides using the undamaged strand as template. The mechanisms include removal of lesions of depurination and DNA glycosylases that recognize altered bases.
  • repeat DNA, repetitive DNA includes (a) satellite DNA and so-called (b) interspersed repeated DNA sequences. The latter are interspread throughout the chromosomes in hundreds of thousands of individual copies, each about 300 nucleotides long; they are, unlike satellite DNA, transcribed.
  • satellite DNA serially repeated DNA sequences of one or a few nucleotides with a repeat length of up to 250 nucleotides that are not transcribed and commonly located in the heterochromatin associated with the centrometric regions of chromosomes.
  • selfish DNA a mobile DNA element that appears to have no function except to replicate itself. Part of junk DNA.
  • DNA sequencing determining the order of nucleotides in DNA from which amino acid in a polypeptide chain can be predicted. Numerous technologies include Maxim-Gilbert, dideoxy, and more recently developed massively parallel systems utilized in proprietary technologies, including 454 and Solexa systems.
  • single-copy DNA the fraction of DNA that contains most of the proteincoding genes and reassociates most slowly.
  • single-stranded DNA produced when double-stranded DNA is denatured or found naturally in some viruses.
  • spacer DNA non-coding DNA sequence situated between genes; used particularly for the non-coding DNA that separates the repeated copies of the ribosomal RNA genes. Called also intergenic spacer.
  • supercoiled DNA the double helix is itself twisted.
  • superhelical DNA a twisted structure formed by circular DNA molecules. See also supercoiled DNA (above).
  • DNA transcription see deoxyribonucleic acid.
  • DNA translation see deoxyribonucleic acid.
  • unique DNA DNA sequences that occur only once in the haploid genome.
  • DNA viruses contain a single molecule of DNA that is either double or single stranded. Parvoviruses and circoviruses are single stranded, hepadnaviruses are partially double stranded, and all others are double stranded. DNA virus families are: Poxviridae, Asfarviridae, Herpesviridae, Adenoviridae, Papillomaviridae, Polyomaviridae, Parvoviridae, Circoviridae, and Hepadnaviridae.
  • Z-DNA an alternative structural form of DNA that differs from the more commonly occurring B- and related A-form in that the helix is left handed compared with the right-hand helixes of B- and A-forms. Z is for zig-zag. The functional significance of Z-DNA is unknown but may be related to strain relief in regions of DNA replication.

• DNA fingerprint [fing′g r-print] a set of distinct DNA fragments created from a sample of cellular DNA that is based on the distribution of highly variable small repetitive elements called minisatellites. The pattern of minisatellites is unique to each individual (with the exception identical twins). DNA fingerprinting is used in genetic research, paternity testing, family genealogy, agriculture, and forensics. Called also DNA profiling. see also restriction fragment length polymorphism (RFLP).

• DNasedeoxyribonuclease. See deoxyribonuclease.

• DNCB dinitrochlorobenzene.

• DNOC dinitro-orthocresol.

• DNP 2,4-dinitrophenol.

• DOA dead on admission (arrival).

• DOB abbreviation for date of birth; used in medical records.

• Doberman pinscher, Dobermann a medium-sized (66–88 lb), lean, muscular dog with very short hair that is usually black with brown markings around the face and on the legs, but occasionally black, red, fawn blue coat. The tail is docked to a short length and where practiced, the normally pendant ears are cropped. The breed is often used for police or guard work. It is subject to cervical spondylomyelopathy (wobbler syndrome), color mutant alopecia, generalized demodicosis, chronic active hepatitis, cardiomyopathy, progressive juvenile nephropathy, von Willebrand disease, and degeneration of the bundle of His. Outside North America called Dobermann.

  • dancing D. disease a very slowly progressive, painless neuromuscular disease in which affected dogs periodically flex one hindleg when standing. Hindleg weakness and atrophy of the gastrocnemius muscle eventually develops. In some cases, both hindlegs are affected with flexion and extension of alternating hindlegs, hence the name.
  • miniature D. p. see Miniature pinscher.

• dobutamine [do-bu′t -mēn] a β1-adrenergic agonist, with weak β2 activity, and α1 selective activity, but no action at dopamine receptors and used clinically in cases of cardiogenic shock to increase heart contractility and cardiac output

• DOC desoxycorticosterone.

• DOCA desoxycortosterone acetate.

• dock¹ [dok] 1. the amputation of a tail; occasionally required for removal of a diseased or damaged tail. Tail docking is commonly performed in dogs, usually in accordance with breed standards that strictly define length, particularly in the spaniel and terrier breeds. Also occasionally done in some draft and harness horses. In both species, the practice is now being viewed as unnecessary and discouraged by many authorities. An almost universal procedure in lambs, for the avoidance of fly strike and carried out by farmers at marking time. Also, a common husbandry practice in pastoral dairy herds where tails full of sloppy feces are unwelcome industrial hazards to farmhands working in pit-type milking parlors, especially on cold mornings. Claimed to reduce the risk for leptospirosis in milkers and to improve udder cleanliness. Amputation is by hot docking iron or by the application of a tight elastic or by the application of a rubber band and is conducted shortly after birth, at weaning or shortly before springing heifers enter the herd. Severe tail docking, the practice of removing the tail close to the point of attachment to the body, used for exhibition purposes in some breeds, increases the risk for rectal prolapse. The practice of docking tails in dairy cattle is banned in many countries. 2. the solid part of a horse’s tail. 3. dock, docked; reduction in price received for an animal at sale because of some defect or problem with the animal, e.g., presence of horns.

• dock² group of plants in the family Polygonaceae. Called also dock sorrel, Rumex spp. Includes bladder dock (R. vesicarius), clustered dock (R. conglomeratus), curled (curly) dock (R. crispus), sour dock, garden sorrel (R. acetosa), swamp dock, Browne’s dock (R. brownii), veined dock (R. venosus).

• docking protein [dok′ing] non-catalytic, intracellular adapter protein in cell signaling that provides a site for assembly of signaling complexes. a ribonucleoprotein particle for targeting proteins to the endoplasmic reticulum (eukaryotes) or plasma membrane (prokaryotes). See signal recognition particle (SRP).

• docking [dok′ing] tail amputation. See dock¹.

  • d. ring see elastrator.

• docosahexaenoic acid an omega-3 (n-3) fatty acid found in the diet or derived from eicosapentaenoic acid (EPA). Cold water fish oils are an especially rich source. See also omega-3 (n-3) fatty acids.

• DOCP desoxycorticosterone pivilate.

• doctor [dok′t r] 1. a practitioner of the healing arts, as one graduated from a college of medicine, osteopathy, dentistry or veterinary medicine and licensed to practice. 2. a holder of a diploma of the highest degree from a university, qualified as a specialist in a particular field of learning.

• docusates [dok′u-sāts] anionic surfactants used as the calcium, sodium or potassium salts as fecal softeners; see dioctyl sodium sulfosuccinate (DSS).

• dodder see Cuscuta.

• doddler calf an inherited, congenital, lethal defect of the nervous system in Hereford calves characterized by continuous clonic convulsions, nystagmus and pupillary dilatation, all present at birth.

• dodine dodecylguanidine acetate, an agricultural fungicide; causes irritation of skin and mucosae; ingestion causes vomiting and diarrhea.

• Dodonaea viscosa a plant in the family Sapindaceae; an unidentified toxin causes liver necrosis and neural astrocyte damage in cattle in South America. Called also sticky hopbush.

• doe an adult female goat or deer; among deer, it is especially common usage in the roe, fallow, muntjac and Chinese water deer species. In the larger species the term cow is used.

• dog [dog] 1. a member of the family Canidae of the order Carnivora. Includes the domestic dog, Canis familiaris, many wild dogs, foxes, fennecs, jackals and wolves. 2. the term is also used by dog people to mean the entire male dog. There is no other name for him as there is in the other species. See also canine.

  • assistance d. one that has been specifically trained to assist a disabled person and certified by an organization that is a full member of Assistance Dogs International or International Guide Dog Federation, the accrediting bodies for assistance dog organizations worldwide. Defined by Assistance Dogs International as an overall term that includes guide dogs for the blind and the visually impaired, hearing dogs for the deaf and hard of hearing, and service dogs for people with disabilities other than those related to vision or hearing. See also service animals, emotional support animals.
  • barkless d. see Basenji.
  • d.-catcher a loop of rope at the end of a pole, with the end of the rope at the holding end of the pole. The loop goes over the dog’s head and is pulled tight.
  • domestic d. classified as hound, gun dog, terriers, nonsporting dog, working dogs, draft² animals, toy breeds. See also individual dog breeds.
  • d. erythrocyte antigen (DEA) see dog erythrocyte antigen.
  • guide d. one trained as an aid to the mobility of a visually impaired person. Guide dogs do not ‘take’ their owners to specific destinations, but respond to commands given for directions. They are of particular value in avoidance of obstacles, both on the ground and overhead. Many breeds have been used for this purpose, but German shepherd dogs and Labrador retrievers are the most common. Called also seeing-eye dogs. See also International Guide Dog Federation.
  • gun d. one of the group of domestic dogs developed for use in hunting fowl. The dogs work with the hunter by detecting the scent of birds on the ground, then indicating their location (setters, pointers) or flushing them from the undergrowth, or by retrieving the fallen bird (retrievers). Called also sporting dogs.
  • hearing d. one trained to respond to certain sounds such as a telephone bell or door knocker and to alert a person with impaired hearing.
  • d. kennel a small box-like unit for housing a single dog, or an establishment that boards dogs, or breeds them or maintains a colony, e.g., a pack of hounds, or a stable of Greyhounds.
  • d. leukocyte antigen (DLA) complex the major histocompatibility complex in dogs.
  • d. murrain chronic selenium poisoning in pastured ruminants. An Irish expression.
  • d. pox a papular balanoposthitis and vaginitis described in young dogs; a viral etiology is suspected, but has never been confirmed.
  • seeing-eye d. see guide dog (above).
  • wild d. includes dingo, Siberian wild dog, the South American bush dog, the maned wolf, Cordillera fox, crab-eating fox, Azara’s fox. See also fox, jackal, wolf.

• dog-ear a defect in skin created when an elliptical surgical incision is too short or one side is longer than the other.

• dog-sitting posture sitting on the haunches like a dog. When cattle or horses sit for long periods on their haunches with the foreparts of their body off the ground and their forelimbs extended like a dog, and if there is difficulty in rising, there may be a musculoskeletal or neurological problem in the area of the pelvis and caudal vertebral column. This dog-sitting posture adopted for short periods by horses and associated with other signs indicative of abdominal pain is usually associated with impaction of the large bowel and pressure on the diaphragm. Also seen with hind limb paresis and paralysis.

• dog-srangling vine see Cynanchum.

• dogbane [dog′bān] see Apocynum cannabinum.

  • spreading d.Apocynum androsaemifolium.

• Dogo Argentino a large, muscular mastiff-type dog used for hunting large game. It has a large head, thick neck, short white haircoat, which may be sparse in warm climates. Called also Argentino mastiff. It is listed as a dangerous breed and importation is prohibited in Australia.

• Dogue de Bordeaux a French breed of dogs resembling the Bull mastiff. The head is massive with a short nose; the coat is short and dark auburn or fawn in color. Called also French mastiff.

• Döhle body [dur′l ] bluish cytoplasmic inclusion of neutrophils made up of retained aggregates of rough endoplasmic reticulum. It is evidence of mild toxic change in the neutrophil. Low numbers can be seen in normal cats.

• dol [dōl] antiquated unit of pain intensity.

• dolasetron [do-las′ -tron] a 5-HT₃ antagonist used as primarily an antiemetic, particularly in association with cancer chemotherapy.

• Dole pony a small Norwegian horse, 14.2–15.2 hands high, most of which are black or brown. Called also Dole-Gudsbrandsdal.

  • D. p. trotter a pony related to Dole pony but lighter in weight and used for harness racing.

• dolich(o)- word element. [Gr.] long.

• dolichocephalic [dol″ľ-ko-s -fal′ik] having a narrow, long head. Characteristic of some dog breeds, e.g., Collie, Borzoi, Greyhound.

  D-36.

  

  Dog-sitting posture in a horse with colic.

• dolichofacial [dol″ľ-ko-fa′sh l] having a long face.

• dolichol [dol′ľ-kol] long-chain lipid molecules consisting of varying numbers of isoprene units and containing an alcohol group. Links oligosaccharide to asparagine residues in proteins via a pyrophosphate bridge; an example of protein glycosylation.

• dolichopellic [dol″ľ-ko-pel′ik] having a long pelvis from cranial to caudal.

• dolicomorphic [dol″ľ-ko-mor′fik] having a long, thin, asthenic body type.

• dollar spots subcutaneous plaques characteristic of the second stage of dourine caused by Trypanosoma equiperdum. See dourine.

• doll’s eye the fixation of the eye in midorbit, unresponsive to vestibular stimulation. Seen in brainstem injury due to damage to the medial longitudinal fasciculus.

  • d. e. reflex symmetrical deviation of the eyes when the head is moved in different positions, always returning to center, but at a slower rate and without the normal siccades expected with a normal oculocephalic reflex. Seen with lesions of the inner ear or brainstem, especially the pons and midbrain. Called also doll’s head reflex.

• doll’s head reflex see doll’s eye reflex.

• dolomite a limestone with a high concentration of magnesium. Used as a mineral supplement for animals. Called also dolomitic limestone.

• dolophine [do′lo-fēn] see methadone.

• dolor [do′lor] [L.] pain; one of the cardinal signs of inflammation.

• dolorific [do″lor-if′ik] producing pain.

• dolorimeter [do″lor-im′ -t r] an instrument for measuring pain threshold. A stimulus (heat, pressure, electrical) of increasing intensity is applied and the intensity required to induce a response is recorded. Called also algesiometer and algometer.

• dolphin a member of the suborder Odonotoceti of the order Cetacea and closely related to whales and porpoises; includes the Amazon and Ganges freshwater dolphins, the common dolphins (Delphinus spp.), bottlenose dolphins (Tursiops truncatus), and the Arctic dolphin, more commonly called the beluga whale.

• domain [do-mān′] 1. region of a protein with a characteristic tertiary structure and function; homologous domains may occur on different proteins. 2. regions of the heavy chain of immunoglobulins. See C_H domain, C_L domain.

  • transmembrane d. for any membrane-bound protein or glycoprotein, those amino acid sequences that traverse and are present in the cell membrane. In receptor biology, transmembrane domains are distinguished from the extracellular ligand binding domains, cytoplasmic domains, and from immunological domains.

• domed forehead bulging of the forehead; in the newborn, it is usually indicative of congenital hydrocephalus or of achondroplastic disease as in dwarfism. A domed forehead is also a sign of prematurity in foals. See also meningocele.

  D-37.

  

  Domed forehead of a premature foal.

• domestic pertaining to an environment managed by humans.

  • d. animals animals accustomed to living in a domestic environment.
  • d. cat often used to describe mongrel or crossbred cats, either shorthaired or longhaired.

• domiciliary [dom″ľ-sil′e-ar″e] pertaining to a household.

  • d. calls professional veterinary calls made to patients at their owners’ residences. Called also house calls.

• dominance [dom′ľ-n ns] 1. the supremacy, or superior manifestation, in a specific situation of one of two or more competitive or mutually antagonistic factors or animals. 2. in genetics, alleles that fully express their phenotype when present in the heterozygous state; see also codominance.

  • d. aggression behavior by an animal that asserts its dominance over another or a human, such as competing for food, resisting control measures, or assuming dominant postures.
  • d. deviation a deviation from gene additive action due to dominance.
  • incomplete d. in a heterozygote, where one allele is not completely expressed over its paired different allele, resulting in a third phenotype.
  • location dependent d. behavior in which an animal is dominant when in its home territory, but it becomes subordinate outside that territory.
  • d. relationship probability of relatives having the same genotype.

• dominant [dom′ľ-n nt] 1. exerting a ruling or controlling influence; in genetics, capable of expression when carried by only one of a pair of homologous chromosomes. 2. a dominant allele or trait. If a defect, appearance in all heterozygotes and homozygotes tends toward the trait being self-limiting because of culling or death. See also gene, dominance.

  • d. X-linked inheritance see X-linked.

• domination the relationship between animals and humans in which little consideration is given to the rights of the animals. The prevailing sentiment is one of proprietary domination.

• domino effect a complication of cervical disk surgery in which compressive lesions develop at the next interspace.

• domperidone [dom-per′ľ-dōn] a dopamine receptor antagonist used as an antiemetic and an appetite stimulant. It is also used to treat agalactia in periparturient broodmares that consumed ergot alkaloids in endophyteinfested fescue grass or hay.

• DON see deoxynivalenol.

• Don horse golden chestnut Russian light horse.

• Donati vertical mattress suture a variation on the vertical mattress suture pattern in which the suture material penetrates the skin on only one side. On the other side it is intracutaneous.

• donkey a member of the family Equidae, Equus africanus asinus or Equus asinus, descended from the wild ass of which there are still many varieties. Characteristically gray to sable in color, short of stature, long, floppy-eared, and with a bray as a call instead of a whinny. Many have a dorsal and shoulder stripes. The male participates in the development of the mule and the female in the production of the hinny. Males are jacks, females are jennies. Called also ass, burro.

  D-38.

  

  Don horse.

  D-39.

  

  Donkey.

  • d. foot an upright, narrow foot with a small sole area and usually a poorly developed frog. Works well on a donkey, but in a horse expected to do fast, hard work, it causes chronic mild lameness. All four feet are affected.
  • d. hide gelatin see ejiao.

• Donnan equilibrium [don′ n] the state of equilibrium that exists at a semipermeable membrane when it separates two solutions containing electrolytes, the ions of some of which are able to permeate the membrane and the others not. The distribution of the ions in the two solutions becomes complicated so that an electrical potential develops between the two sides of the membrane, and the two solutions have different osmotic pressures. Called also Gibbs–Donnan equation or equilibrium.

• donor [do′n r] 1. an organism that supplies living tissue to be used in another body, as an animal that furnishes blood for transfusion, or an organ for transplantation. 2. a substance or compound that contributes part of itself to another substance (acceptor).

• Donskoy cat a breed of Russian cat characterized by hairlessness, caused by a dominant gene mutation.

• dopa [do′p ] l-3,4-dihydroxyphenylalanine. Key intermediate in two pathways; the production of melanins from tyrosine catalyzed by the copper-containing enzyme, tyrosinase, to produce dopa, or the biosynthesis of catecholamines catalyzed by the action of tyrosine. It is used in manganese poisoning. Precursor of dopamine able to cross the blood–brain barrier. Called also l-dopa and levodopa. Used as a therapeutic agent for condition of dopamine deficiency such as Parkinson’s disease.

• dopamine [do′p -mēn] a compound, hydroxytyramine, produced by the decarboxylation of dopa; an intermediate product in the synthesis of norepinephrine. It is a neurotransmitter in the central nervous system; administered intravenously to correct hemodynamic imbalance in shock syndrome.

  • d. agonist compounds that bind with and stimulate dopamine receptors. Includes bromocriptine, cabergoline, pergolide and l-deprenyl (selegiline).
  • d. β-hydroxylase enzyme catalyzing the synthesis of norepinephrine from dopamine. A copper-containing mono-oxygenase requiring vitamin C (ascorbic acid).

• dopaminergic [do″p -mēn-ur′jik] activated or transmitted by dopamine; pertaining to tissues or organs affected by dopamine.

• dopexamine a β₂-andrenergic receptor agonist with positive inotropic effects.

• doping [do′ping] the illicit administration of drugs or other agents to racing animals with the intention of altering their physical performance, either adversely or positively. Called also sting.

• doppellender, doppellendigkeit [dop′ l-en″d r] [Ger.] see myofiber hyperplasia.

• Doppler [dop′l r] named after Christian Doppler (1803–1853), an Austrian physicist and mathematician.

  • duplex D. imaging see Doppler ultrasound.
  • D. effect the relationship of the apparent frequency of waves, as of sound, light and radio waves, to the relative motion of the source of the waves and the observer. The frequency increases as the two approach each other and decreases as they move apart. The Doppler effect can be experienced when a train whistle or automobile horn produces a continuous sound as it approaches and passes a listener. The pitch of the sound suddenly falls as the source passes the listener.
  • D. shift the change in frequency that occurs when high-frequency sound waves are reflected from a moving surface; the basis for Doppler ultrasound.

• Doppler ultrasound [dop′l r] that in which measurement and a visual record are made of the shift in frequency of the ultrasound beam proportional to the blood-flow velocity in underlying vessels. Also used to assessment movement as in tissue Doppler of the myocardium.

  • color flow D. u. a form of pulse wave Doppler in which the energy of the returning echoes is displayed as an assigned color; by convention echoes representing flow toward the transducer are seen as shades of red, and those representing flow away from the transducer are seen as shades of blue. The color display is usually superimposed on the B-mode image, thus allowing simultaneous visualization of anatomy and flow dynamics.
  • continuous wave D. u. a technique in which the transducer emits and receives the ultrasound beam continuously, enabling the measurement of high-velocity blood flow, such as occurs through heart valve stenoses.
  • duplex D. u. a form of image display in which both spectral and color flow images are seen simultaneously. This facilitates accurate anatomical location of the blood flow under investigation.
  • D. u. flow meter a device for measuring blood flow that transmits sound at a frequency of several megahertz downstream along the flowing blood. Some of the sound waves are reflected by the moving red blood cells back toward the transducer. The difference in pitch between the transmitted and reflected sounds is produced as an audible tone and is proportional to the velocity of blood flow. The flow meter can be incorporated into a stethoscope so that qualitative and quantitative measurements of the flow of blood through arteries and veins can be obtained. The Doppler flow meter is capable of recording very rapid pulsatile changes in flow as well as steady flow.
  • power D. u. a form of pulse wave Doppler in which the integral of the power spectrum is estimated and color coded. The colors indicate that blood flow or other motion is present but display no information of flow direction or velocity. The color display is usually superimposed on the Bmode image, thus allowing simultaneous visualization of anatomy and the flow dynamics. Useful for regions of low blood flow.
  • pulse wave D. u. a technique in which the transducer emits ultrasound in pulses. Blood flow velocities so measured are limited to around the physiologic range (up to approximately 1.5 m/s) but the depth from which the returning echoes originate can be accurately determined.
  • spectral D. u. a form of ultrasound image display in which the spectrum of flow velocities is represented graphically on the y-axis and time on the x-axis; both pulse wave and continuous wave Doppler are displayed in this way.

• doramectin a macrocyclic lactone parasiticide; one of the avermectins used as an antiparasitic agent in agricultural animals.

• Dorgi a designer dog produced by crossing a Dachshund and a Pembroke Welsh Corgi; a favorite of Queen Elizabeth II.

• doripenem a β-lactam antibiotic of the carbapenems class.

• Dormer South African dual-purpose sheep with fleece of 22- to 24-micron fiber diameter. Produced by crossing Merino and Dorset Horn breeds.

• dormitory effect the apparent influence on promoting estrus in bitches when they are housed with other intact bitches who are cycling.

• dormouse small, omnivorous, arboreal rodent with a furred tail in the family Gliridae with characteristics of both mice and squirrels. Most species are nocturnal and may hibernate many months per year. They are often heavily parasitized by ticks and are important reservoirs for the spirochete that causes Lyme disease.

• dornase [dor′nāz] a shortened term for deoxyribonuclease; also a word termination, as in streptodornase.

• Doronicum hungaricum European plant in the family Asteraceae; contains an unidentified toxin that causes paralysis and convulsions. Called also wild sunflower.

• Dorper South African meat sheep bred by crossing Blackhead Persian with Dorset horn sheep; white with black head, black feet, and a hairy, carpetwool fleece.

• dorsad [dor′sad] toward the back.

• dorsal [dor′s l] directed toward or situated on the back surface, the surface facing away from the ground; opposite the ventral.

• dorsalgia [dor-sal′j ] pain in the back.

• dorsalis [dor-sa′lis] [L.] dorsal.

• Dorset short white wool, meat sheep, with large, curled horns; widely used as fat lamb sire. Wool is medium-fine at 27 microns. There are horned and polled varieties.

• Dorset Down English short wool, meat sheep, polled, with brown face and legs originating from Hampshire ewes crossed with Southdown rams. Now a minority breed.

• dorsiflexion [dor″sľ-flek′sh n] backward flexion or bending, as of the neck.

• dors(o)- word element. [L.] the back; in animals, the upper aspect of the body.

• dorsocephalad [dor″so-sef′ -lad] toward the back of the head.

• dorsolateral [dor″so-lat′ r- l] pertaining to the back and side.

  • d. tract a group of nerve fibers in the lateral funiculus of the spinal cord that cap the dorsal column.

• dorsopalmar [dor″so-pal′m r] the passage of an x-ray beam from the dorsal aspect of the forelimb to the palmar aspect. Its use is limited distal to the antebrachiocarpal joint.

• dorsoplantar [dor″so-plan′t r] passage of an x-ray beam from the dorsal aspect of the hindlimb to the plantar aspect. Its use is limited to distal to the tarsocrural joint.

• dorsoventral [dor″so-ven′tr l] 1. pertaining to the back and belly surfaces of a body. 2. passing from the back to the belly surface.

  • d. projection in radiology, the image resulting from passage of the x-ray beam from the dorsal to the ventral side of the body.

• dorsum [dor′s m] pl. dorsa [L.] 1. the back; the superior surface of a body or body part, as of the paw or foot. 2. the aspect of an anatomical structure or part corresponding in position to the back; posterior in bipeds.

• dorzolamide [dor-zo′l -mīd] a topical carbonic anhydrase inhibitor used in the treatment of glaucoma.

• dosage [do′s j] 1. in pharmaceutical terms is the determination and regulation of the size, frequency, and number of doses. 2. genetically speaking, refers to the number of copies of a particular gene present in the genome; gene duplications or gene deletions can alter the gene dosage.

  • d. compensation compensation, by random X-inactivation, of the dosage of X-linked gene material in the cells of males and females; typically only one X chromosome remains active in any given cell regardless of sex.

• dose [dōs] the quantity to be administered at one time, as a specified amount of medication or a given quantity of radiation.

  • absorbed d. that amount of energy from ionizing radiation absorbed per unit mass of matter, expressed in Grays.
  • air d. the intensity of an x- or gamma-ray beam in air, expressed in coulombs per kilogram.
  • booster d. an amount of immunogen (vaccine, toxoid, or other antigen preparation), sometimes smaller than the original amount, injected at an appropriate interval after primary immunization to enhance and sustain the immune response to that immunogen.
  • curative d. (CD) a dose that is sufficient to restore health or resolve clinical signs; mostly used in pharmacologic studies.
  • divided d. a fraction of the total quantity of a drug prescribed to be given at intervals, usually during a 24-hour period, for example, the total daily dose, divided into two doses, one given in the morning, the other in the evening.
  • d. equivalent limits the limits of ionizing radiation set for radiation workers and the general public by the International Commission on Radiological Protection.
  • fatal d. lethal dose.
  • d. fractions in radiation therapy, the small doses given to reach the total radiation dose during the treatment period.
  • infectious d. 50 (ID₅₀) that amount of pathogenic microorganisms that can be expected to result in infection of 50% of the test subjects. Called also the median infectious dose.
  • infective d. (ID) that amount of pathogenic microorganisms that will cause infection in susceptible subjects.
  • lethal d. (LD) the amount of toxin or drug that is fatal to an animal.
  • d. level the amount administered per unit of body weight, for example, X mg/kg body weight.
  • loading d. the initial larger dose of a drug given to reach effective fluid and tissue concentrations quickly; also called also the priming dose.
  • maintenance d. the smaller doses needed to maintain effective concentrations in body fluids and tissues after the loading dose has achieved the therapeutic concentration.
  • maximum permissible d. see dose equivalent limits (above).
  • median curative d. (CD₅₀) a dose that resolves clinical signs in 50% of test animals.
  • median effective d. (MED) the dose that produces the desired effect in 50% of the test animals.
  • median lethal d. (MD₅₀) the quantity of an agent that killed 50% of the test subjects; in radiology, the amount of radiation that is lethal, within a specified period, in 50% of individuals in a large group or population.
  • minimum lethal d. (MLD) the lowest dose that caused death in the test subjects.
  • d. rate the amount administered per unit of time.
  • d. response 1. the incremental change in the subject per unit of additional dose. The response as a function of the dose. 2. the frequency of occurrence of a disease as the intake of the suspected risk factor increases.
  • skin d. 1. the air dose of radiation at the skin surface, comprising the primary radiation plus backscatter 2. the absorbed dose in the skin.
  • tolerance d. the largest quantity of an agent that may be administered without harm.

• dose-related see dose response.

• dosimeter [do-sim′ -t r] an instrument used to detect and measure exposure to radiation.

  • d. badge see film badge.
  • thermoluminescent d. (TLD) a radiation safety badge worn by personnel. Contains materials that trap electrons; later measured to determine the amount of exposure.

• dosimetry [do-sim′ -tre] scientific determination of amount, rate and distribution of radiation emitted from a source of ionizing radiation. See film badge.

• dosing injuries [do′sing] injuries inflicted on patients with dosing equipment. Includes buccal and pharyngeal injuries with balling guns, dosing syringes, drenching guns, esophageal and nasal tubes, gags, and specula.

• double-blind study [dub′ l blī nd] a study of the effects of a specific agent in which neither the administrator nor the recipient, at the time of administration, knows whether the active or an inert substance is given.

• double gee see Emex australis.

• double scalp palpable osteoporotic thinning of the cranial bones in young sheep on inadequate diet. Called also cappi.

• double-seeded emu bush see Gyrostemon tepperi.

• douche [doosh] [Fr.] a stream of water or air directed against a part of the body or into a cavity.

  • air d. a current of air blown into a cavity, particularly into the tympanum to open the eustachian tube.
  • vaginal d. irrigation of the vagina to cleanse the area, to apply medicated solutions to the vaginal mucosa and the cervix.

• dough stage a stage in the maturation of a cereal crop when the seeds are soft and immature but fully formed. This is the optimum time to convert the crop into hay or ensilage.

• dourine [doo-rēn′] a sexually transmitted trypanosomiasis of horses, donkeys and mules and endemic in parts of Africa and Asia, including Russia, caused by Trypanosoma equiperdum, characterized primarily by inflammation of the external genitalia, but with progressive infection, edema of the ventral abdominal wall, muscle weakness, incoordination and paralysis. Severe loss of condition may be followed by emaciation to the point where euthanasia is necessary. Urticaria-like plaques called silver dollar spots occur on the skin in some forms of the disease.

• douroucouli see owl monkey.

• dove a bird that together with the pigeon forms the large bird family Columbidae. There appears not to be a clearcut distinction between the two groups and some types have alternative names, one of them a pigeon, the other one a dove. They vary in color, typically having a stout body, short legs and neck, and the legs are clean of feathers.

• dowel [dou′ l] a slim cylinder of bone consisting of two plates of cortical bone separated by an internal sandwich of cancellous bone. Used for fusing bones or reconstructing large bones.

• down feather [doun] small feathers whose barbs do not unite to form a closed vane, thus giving it a fluffy appearance. See also feather.

  D-40.

  

  Chronic wasting and poor body condition in a horse with dourine.

• down regulation [doun″reg-u-la′sh n] means of controlling hormone action where the number of hormone receptors at the cell surface is decreased by internalization of the receptor complex.

• down staging the use of chemotherapy or radiation therapy prior to surgery to reduce the pathological stage of a neoplasm. See also staging (2).

• downer a non-ambulatory animal, one not able to stand, which may result from a variety of causes including broken limb bones, neurological diseases, muscular disease, or terminal systemic disease. The term is particularly used for animals that are presented for slaughter. Historically, these animals have been accepted or rejected for slaughter subject to preslaughter veterinary examination to determine cause and acceptability. Currently, in many countries, it is now illegal for downer animals to be bought, sold, transported, or slaughtered for human consumption. This is, in part, because of risk for human exposure to bovine spongiform encephalopathy in downer cattle. However, with all animal species, a major public concern is one of animal welfare, because the facilities in abattoirs, or in some cases the culture, is inadequate to handle these animals in a humane fashion.

• downer cow syndrome a commonly fatal condition of dairy cows closely associated with the unsuccessful treatment of cases of hypocalcemic parturient paresis and manifest with inability to rise from sternal or lateral recumbency. At postmortem examination, there is a variety of contributing lesions including especially ischemic necrosis of the muscles of the thigh, damage to major nerves to the hindlimb, traumatic separation of muscles and tendons, hip dislocation, and hepatic and myocardial degeneration.

  • prepartum d.c.s. preparturient cows that become recumbent and are unable to rise. Occurs occasionally in beef and dairy cows; associated with hypocalcemia, severe prepartum weight loss and ketosis in beef cattle, and hydrallantois in both cattle types.

• downhill vagina the cranial vagina is lower than the vestibule so that drainage is inadequate; results in urine pooling, urovagina, and urometra.

• Downs sheep a group of breeds of British shortwool or mutton breeds of sheep of local origins in England. All are polled and most have some Southdown blood. Raised primarily for meat. Includes Dorset Down, Southdown, Oxford Down, Suffolk, Hampshire, Shropshire.

• downstream [doun′strēm] a term used in molecular biology to describe nucleotides of a nucleic acid molecule that lie in the 3′ direction from a particular reference point, such as the site of initiation of transcription. See also upstream.

• doxacurium [dok″s -ku′re- m] a long-acting, nondepolarizing muscle relaxant.

• doxapram [dok′s -pram] an analeptic and respiratory stimulant that acts within the central nervous system; it has been used to reverse sedation, the antagonism is not specific.

• doxepin [dok′s -pin] a tricyclic antidepressant and potent histamine type 1(H₁₎-receptor blocker, similar to amitriptyline, used in the treatment of pruritus in dogs and cats.

• doxorubicin [dok″so-roo′bľ-sin] an antineoplastic antibiotic obtained from Streptomyces sp. that binds to DNA and inhibits synthesis of nucleic acids and cell division. Commonly used chemotherapeutic agent in veterinary medicine. The side effects include bone marrow depression, alopecia, and cardiac toxicity.

• doxycycline [dok″se-si′klēn] a second-generation, lipid-soluble orally active tetracycline derivative with greater activity against anaerobes and intracellular bacteria and a longer half-life. Used as the monohydrate.

• doxylamine [dok-sil′ -mēn] an antihistamine used in the treatment of allergic reactions in cattle.

• Doyen forceps [dwah-yah′] lightly compressive, long-bladed, curved forceps and a rachet handle designed for intestinal compression. The blade faces are lightly grooved along their length. Called also Gillman forceps.

• DP designated person.

• DPG diphosphoglycerate.

• DPN diphosphopyridine nucleotide. Also known as nicotinamide adenine dinucleotide (NAD⁺).

• Dr. Doctor.

• dr dram.

• Dr. Larson’s teat tube a plastic, self-retaining tube with a blunt end and side holes which acts as a permanent drain for the quarter. It has a screwon cap so that the drainage can be arrested. Good for retaining patency after teat surgery.

• Dromaius novaehollandiae see emu.

• Drabkin’s solution a solution containing potassium ferricyanide and potassium cyanide; used in a technique for hemoglobin estimation.

• drachm archaic spelling for dram.

• dracunculiasis, dracunculosis [dr -kung″ku-li′-sis, dr -kung″ku-lo′sis] infection and infestation by nematodes of the genus Dracunculus.

• Dracunculus [dr -kung′ku-l s] a genus of spiruroid nematode parasites in the family Dracunculidae. Includes D. alii, D. dahomensis, D. globocephalus, D. ophidensis (all in reptiles), D. fuelleborni (in opossum), and D. lutrae (in otter).

  • D. insignis a spiruroid nematode infesting dogs and wild carnivores. Causes cutaneous lesions and ulcers, sometimes internal lesions, e.g., in heart and vertebral column. Called also dragon, fiery dragon, or guinea worm.
  • D. medinensis a thread-like worm widely distributed in North America, Africa, the Near East, East Indies, and India; frequently found in the subcutaneous and intermuscular tissues of humans and also in dogs, sometimes horses and cattle. Causes cutaneous nodules and subsequently ulcers.

• draft¹ a potion or dose.

• draft² 1. the hauling of vehicles, implements, and other loads. 2. separation of a group of animals into different classifications, e.g., those for sale and those to be kept for breeding. Commonly a procedure performed in a drafting race or chute and through a drafting gate.

  • d. animals includes dogs, horses and other Equidae, oxen, reindeer, yak, elephant, water buffalo.

• draft horses see draft² animals.

• Dräger vaporizer a precision vaporizer; is temperature compensating and calibrated to deliver precise concentrations of halogenated gas anesthetics.

  • North American D. v. a mechanical ventilator that operates as a flow generator and controller.

• dragon see Dracunculus insignis.

• drain [drān] 1. to withdraw liquid gradually. 2. any device by which a channel or open area may be established for exit of fluids or purulent material from a cavity wound, or infected area.

  • active d. continuous or intermittent suction is used for greater efficiency in fluid removal.
  • cigarette d. a drain made by drawing a small strip of gauze or surgical sponge into a tube of gutta-percha or rubber.
  • passive d. relies on gravity and must be placed in a dependent position.
  • Penrose d. a thin tube of latex rubber; secretions drain around, not through this tube.
  • sump d. a drainage system in which a small air tube is located inside the lumen or wall of a larger tube that drains fluid from a cavity.
  • underwater d. the external opening of the drainage tube is immersed in a sealed container of water; used for drains from the pleural cavity to collect drainage yet maintain a mild negative pressure.

• drainage [drān′ j] systematic withdrawal of fluids and discharges from a wound, sore or cavity.

  • d. angle iridocorneal angle.
  • capillary d. that effected by strands of hair, catgut, spun glass, or other material of small caliber that acts by capillary attraction.
  • closed d. drainage of an empyema cavity carried out with protection against the entrance of outside air into the pleural cavity.
  • open d. drainage of an empyema cavity through an opening in the chest wall into which one or more rubber drainage tubes are inserted, the opening not being sealed against the entrance of outside air.
  • peritoneal d. drainage of the peritoneum; limited by the rapid formation of adhesions and can only be accomplished with lavage or through an open cavity.
  • suction d. a source of continuous or intermittent negative pressure is used to maintain drainage in various sites, particularly negative pressure in the pleural cavity. A syringe and valve, one-way valve, vacuum tube, or underwater drain can be used for this purpose.
  • d. systems see drain.
  • tidal d. drainage of the urinary bladder by an apparatus that alternately fills the bladder to a predetermined pressure and empties it by a combination of siphonage and gravity flow.
  • d. tubes see drain.

• Draize test used by pharmaceutical and chemical companies to test the acute toxicity of products in the eyes of animals, usually albino rabbits. Now abandoned as the result of active opposition by a number of individuals and animal welfare organizations.

• drake [drāk] 1. male duck. 2. Lolium temulentum.

• Drakensberger a black breed of cattle used for meat and dairying, produced in South Africa. Called also Black Africander.

• dram [dram] a unit of weight in the avoirdupois (27.344 grains, 1/16 ounce) or apothecaries’ (60 grains, 1/8 ounce) system; symbol.

• fluid d. a unit of liquid measure of the apothecaries’ system, containing 60 minims, and equivalent to 3.697 ml. See Table 2.3. Abbreviated fl. dr.

• drape the cloth used to cover the animal for surgery leaving exposed only that part of the body that has been aseptically prepared and is actually required for the surgical procedure. Applying the drapes is called draping.

• draping [drāp′ing] covering the animal with sterile drapes for surgery leaving exposed only that part of the body that has been aseptically prepared and is actually required for the surgical procedure. Creates the surgical field.

• Draschia [dră′she- ] a genus of the worm family of Habronematidae. Includes D. megastoma (syn. Habronema megastoma) found in often large intramural nodules in the stomach wall of horses.

• drastics [dras′tik] a term used to describe highly irritant laxatives.

• drawer sign a clinical test of joint stability, particularly the stifle (knee).

  • cranial (anterior) d. s. cranial, nonrotary movement of the proximal tibia in relation to the distal femur. Normally restricted by the cranial (anterior) cruciate ligament and used as a diagnostic test for rupture of that structure.
  • caudal (posterior) d. s. instability of the stifle joint with caudal movement of the proximal tibia in relation to the distal femur; normally restricted by the intact caudal (posterior) cruciate ligament. This movement is used as a test in the diagnosis of rupture of that ligament in the dog.
  • shoulder d.s. used in the diagnosis of bicipital tenosynovitis in dogs

• drawing knife see hoof knife.

• Drechslera [dreks′l -r] genus of molds in the phylum Ascomycota; includes D. biseptata, D. campanulata. Most are now classified as Bipolaris spp. or Exserohilum spp.

  • D. rostrata a fungus isolated from nasal cavities of cattle affected by enzootic nasal granuloma. Now called Exserohilum rostratum.
  • D. spicifera an obsolete name for Bipolaris spicifera. The imperfect state of Cochliobolus spicifera. Associated with phaeohyphomycosis in animals.

• drench [drench] 1. to give medicines in liquid form by mouth and forcing the animal to drink. See also drenching. 2. medicines given as a drench.

  • saline d. an orally administered preparation of electrolytes in water used in racehorses but more particularly in endurance and event horses in which heavy electrolyte losses in sweat are likely. A variety of formulations is used but all contain sodium, potassium, calcium, and magnesium ions; some also contain glucose.

• drenching farmer’s term for the administration of medicines as solutions or suspensions in water by mouth with a drench bottle, gun, or funnel.

  • d. bit to be included in a bridle as a bit. Has a hollow tube instead of a solid bit, with perforations, and an inlet to which a funnel is fitted. The drench material is poured into the funnel and exits into the mouth.

    D-41.

    

    Drepanocytes (sickle cells) in a blood film from a normal deer.

  • d. gun injury laceration of the oral mucosa or fauces or pharynx with the nozzle of the gun, due usually to over-vigorous attempts to use the gun as a device to open the jaws or over-vigorous insertion.

• Drentsche patrijshond a medium-sized Dutch spaniel with medium length, white coat with large brown plates (spots). Called also Dutch partridge dog.

• drepanocyte [drep′ -no-sīt] a sickle cell; occur commonly in the preparation of normal deer blood.

• drepanocytosis [drep″ -no-si-to′sis] occurrence of drepanocytes (sickle cells) in the blood.

• dressage the dressing of a riding horse as distinct from the training of a racing horse. The term has come to include formal training and competition in a standard arena and with standard furniture for jumps and a standard layout for the course to be followed. The formal training comprises a complex series of exercises in deportment for the horse and rider. They require great precision in execution so that the quintessence of the training is the lightness of the commands and controls and the degree to which the horse and rider are collected in their movements.

• dressed seed corn cereal grain intended for seed and treated with antifungal agents; it is often fed to livestock when it is not needed for seed and may cause poisoning. See seed dressing.

• dressed weight weight of a carcass of an animal being prepared for use as meat; the head, lower limbs, skin (with the exception of poultry, which have, however, been defeathered), and viscera (except kidney) have been removed.

• dressing [dres′ing] 1. any of various materials used for covering and protecting a wound. A pressure dressing is used for maintaining constant pressure, as in the control of bleeding. A wound dressing is used to protect and promote the healing of an open wound. A protective dressing is applied to shield a part from injury or from septic infection. 2. of a carcass of meat see carcass dressing.

  • biological d. skin grafts.
  • butterfly d. an adhesive dressing used to hold wound edges together.
  • dry d. support and pressure bandages not applied to moist wounds.
  • line d. (2) a system of handling carcasses in an abattoir. The carcasses move along an overhead chain line past a series of stations where the dressing and meat inspection is done.
  • occlusive d. 1. a surgical dressing applied to close off an aperture, e.g., a trephine opening into a maxillary sinus. 2. a dressing used on the skin that retains moisture and heat while increasing the concentration and absorption of medication being applied.
  • on-the-rail d. (2) abattoir dressing of carcasses while they are still suspended from an overhead monorail and workers are stationed at key points along the chain.
  • d. percentage (2) see carcass yield.
  • wet d. soaking of a bulky dressing to aid in cleansing, drainage, and débridement of a wound. May be applied intermittently or continuously.

• dressing-out percentage see carcass yield.

• Drever a short-legged, long-bodied scent hound from Sweden with characteristics of the Dachshund and the Beagle. Used for deer hunting in Sweden and Norway.

• dribblers steers in feedlots with incomplete urethral obstruction by urinary calculi so that they pass small amounts of urine frequently. In some of these cases the calculus has an irregular shape and permits the passage of some urine.

• dried fruit mite itch see Carpoglyphus.

• drift [drift] chance variation; in genetics, the random changes in gene frequencies in a population.

  • antigenic d. see antigenic drift.
  • d. lambing a strategy in which ewes that have lambed are periodically removed from a flock of lambing ewes by moving the unlambed ewes on to the next paddock or field.

• drifting sideways the patient moves gradually to one side when attempting to walk in a straight line.

• drill¹ [dril] (Mandrillus leucophaeus) one of the Old World monkeys; in the same genus as mandrills, which it resembles. It has the characteristic ridged and grooved nasal bones, but with a black face, and bright red skin on the rump. An endangered species.

• drill² in dentistry, a mechanical device used for removing dental hard tissue, firm soft tissue, and restorative and other materials. See also bur.

• Drimia an African-Mediterranean plant genus in the family Liliaceae (Hyacinthaceae); contain bufadienolide cardiac glycosides; causes abdominal pain, cardiac irregularity, diarrhea, dyspnea, and sudden death.

• drinking water [drin′king] supply of water available to animals for drinking supplied via nipples, in troughs, dams, ponds, and larger natural water sources; an insufficient supply leads to dehydration; it can be the source of infection, e.g., leptospirosis, salmonellosis, or of poisoning, e.g., fluorine, sodium chloride.

• Drinkwater mouth gag a mouth gag for use in cattle and horses. Made of cast aluminum, it consists of two wedges, one for each side of the mouth, which are pushed up between the upper and lower molars. The reflex clamping of the jaws ensures that they are retained. Gives access to the pharynx and the incisors are in full view.

• drip [drip] the slow, drop-by-drop infusion of a liquid.

  • postnasal d. drainage of excessive mucous or mucopurulent discharge from the postnasal region into the pharynx.
  • d. rate pumps a mechanical device used to deliver a constant rate of intravenous fluids. It applies pressure to the fluid line through a set of rollers.

• dripping [drip′ing] 1. continuous discharge of an exudate or secretion. 2. rendered beef fat.

• drive census [drīv] collection of data about a population by herding them all together, making a complete muster for an area.

• driving disease [drīv′ing] see ovine pulmonary adenomatosis.

• dromedary The one-humped Arabian camel (Camelus dromedarius), widely distributed in North Africa and the Middle East, with an introduced feral population in Australia. See Camelus.

• dromotropic [drom″o-tro′pik] pertaining to dromotropy.

• dromotropy affecting conductivity of a nerve fiber; it may be positive or negative.

• dronabinol a synthetic form of the cannabinoid, tetrahydrocannabinol (THC). Used as an anti-emetic and appetite stimulant

• Droncit [dron′cit] a proprietary name for praziquantel.

• dronkgras see Melica decumbens.

• drooling the discharge of saliva from the mouth. A normal feature in some breeds of dogs such as Saint Bernard, Newfoundland, and English bulldog, presumably because of their loose, pendulous lips. In other animals it can be a sign of abnormalities of swallowing, painful oral lesions, diseased teeth, esophageal disease, nausea, hepatic encephalopathy, some intoxications, and disorders of salivary glands with hypersialosis.

• drooping quarters see goose-rumped.

• droperidol [dro-per′ľ-dol] a butyrophenone tranquilizer once used as a narcoleptic preanesthetic and, in combination with fentanyl citrate, as a neuroleptanalgesic.

• droplet [drop′l t] very small drop of fluid.

  • d. nuclei the finite particles of matter that are transmitted from animal to animal.

• dropout a patient that becomes inaccessible or ineligible to follow-up procedures.

• dropped said of an anatomical part that has fallen below its usual position.

  • d. abdomen pendulous abdomen due to muscle weakness or rupture of prepubic tendon.
  • d. elbow results from injury to the axillary and/or thoracodorsal nerves and paralysis of the flexors of the shoulder. Occurs in injuries to the brachial plexus or its roots, such as avulsion. See also radial paralysis.
  • d. jaw see mandibular neuritis.
  • d. muscle rupture of the gracilis muscle.
  • d. sole a lesion only in the horse. Loss of connection between the hoof wall and pedal bone result in downward (distal) displacement of the pedal bone within the hoof, causing loss of the usual concavity of the sole. Associated with laminitis and loss of integrity of the sensitive laminae.
  • d. toe rupture of the extensor tendons and dorsal elastic ligament of a toe in a dog; especially common in racing Greyhounds.
  • d. udder see mammary suspensory ligament rupture.
  • d. wrist ventriflexion and weakness of the hand in primates with severe demineralization because of dietary deficiency of vitamin D alone or in combination with calcium.

• dropper [drop′ r] 1. a pipette or tube for dispensing liquids in drops. 2. a wooden or metal spreader holding the wires in a farm fence apart.

• droppings [drop′ingz] a term commonly applied to feces.

• dropsical [drop′sľ-k l] affected with or pertaining to dropsy.

• dropsy [drop′se] an abnormal accumulation of serous fluid in a body cavity or in the cellular tissues; called also hydrops, edema. See also edema, fetal anasarca.

  • fetal d. see fetal anasarca.
  • fetal sacs d. see hydrallantois, hydramnios.
  • placenta d. placental edema; usually accompanies placentitis or fescue toxicosis.
  • tropical fish d. associated with bacterial infections, particularly Aeromonas or Pseudomonas spp. Called also pinecone disease because of the appearance of the distended abdomen with protruding scales.

• dropwort [drop′wort] see water dropwort.

• Drosanthemum genus of southern African plants in the family Aizoaceae; contain soluble oxalates that may cause nephrosis. Includes D. floribundum (vygie).

• Drosera genus of insectivorous plants in family Droseraceae; some species may cause cyanide poisoning. Called also sundews.

• drought feeding feeding of cattle and sheep on minimal diets to maintain life during periods of poor rainfall and pasture growth. Requires judgment to avoid animals reaching an irreversible stage of inanition.

• drought-resistant pasture types or animal breeds that survive better than others during periods of low rainfall.

• Droughtmaster a red, polled or horned breed of beef cattle produced in Australia by crossing Brahman and Shorthorn breeds.

• droving 1. moving cattle or sheep from one place to another by driving them slowly on foot along roadways or stock routes. 2. in less temperate climates the same exercise conducted by truck is called droving.

• drowning [droun′ing] death from suffocation resulting from aspiration of water or other liquid substance or fluid. Drowning occurs because the liquid prevents effective ventilation of the lungs.

  • dry-d. asphyxiation, but with little or no inhalation of water as a result of persistent laryngospasm.
  • near-d. see near-drowning.
  • secondary d. pulmonary edema can occur some time after a near-drowning due to loss of surfactant.

• drug [drug] 1. any medicinal substance. 2. a narcotic. 3. to administer a drug.

  • d. administration includes aerosol, oral, transtracheal infusion, subcutaneous, intramuscular, intravenous, intrauterine, intraperitoneal, intraarticular, intramammary, intrathecal, subconjunctival, percutaneous, percutaneous intraruminal, gas inhalation. Mass medication via feed or drinking water or, in the case of captive fish, in the tank water. For feral animals individual dosing by projectile dart is usual, for group therapy administration by bait is possible.
  • d. allergy immune-mediated hypersensitivity to a drug molecule. Ranges from mild urticaria to anaphylactic shock.
  • animal d. a drug specifically tested for, and recommended for use in, animals. A legal point of importance if an animal dies as a result of an unusual or allergic reaction to medication with a drug not licensed for use in animals.
  • d. augmented swine dysentery pigs receiving prophylactic medication are more severely affected by the disease than untreated pigs.
  • bactericidal/bacteriostatic d. see antibiotic.
  • d. binding binding of a drug to a large molecule in the tissues or fluids, e.g., binding to protein in the blood, may affect the metabolism of the drug, especially its rate of excretion.
  • chemotherapeutic d. see chemotherapy.
  • d. combinations a pharmaceutical strategy of combining several drugs into one formulation to provide for a specific requirement, e.g., an antibiotic combined with an anti-inflammatory agent in a mastitis ointment. Has the disadvantage that the dose of one drug is determined by the dose of the other.
  • controlled d. availability and use of the drug is controlled by law. The control is at various levels of intensity depending on the degree of danger associated with the uncontrolled use of each drug.
  • d. delayed swine dysentery swine dysentery appears several days after treatment is discontinued.
  • d. delayed-augmented swine dysentery after successful treatment during an attack of swine dysentery a more severe form of the disease occurs after treatment ceases.
  • d. diminished swine dysentery the disease is reduced in severity as a result of treatment but is not eliminated.
  • d. eruption an eruption or solitary skin lesion caused by a drug. See also dermatitis medicamentosa.
  • d. hypersensitivity see drug allergy (above).
  • mutagenic d’s one that affects the DNA of the target organism, with the hazard of creating new strains of microorganisms with increased pathogenicity.
  • new animal d. a drug intended for use for animals other than man that is not generally recognized by qualified experts as safe and effective for use under the condition prescribed, recommended, or suggested in its labeling.
  • d. residue the amount of the drug that can be detected in tissues at specified times after administration of the drug ceases. See also drug tolerance.
  • d. resistance said mainly of antibacterial drugs and of microorganisms that are unaffected by the drug while most organisms of its species are susceptible. The resistance may be inherent or secondary to frequent exposure at sublethal concentrations. Resistance of an animal to a specific drug, e.g., to insulin, can also occur in this way.
  • d. resistant swine dysentery medication of the feed is not effective and diarrhea and deaths occur despite treatment.
  • d. safety margin the magnitude of the difference between the dose required to produce a maximum therapeutic effect and that which produces a toxic effect. Registering authorities require this information.
  • scheduled d’s. a drug subject to controls that regulate who may possess, prescribe or use it. In most countries, drugs are classified into different schedules according to accepted medical use and potential for abuse. In the US, the Controlled Substances Act places all substances into one of five schedules. For example, heroin and lysergic acid diethylamide (LSD) are Schedule I substances;coughmedicines with codeine are examples of Schedule V drugs. The schedule number determines who may prescribe it and the requirements for storage in a veterinary pharmacy.
  • d. selectivity capacity to produce a single, specific effect.
  • teratogenic d. produces a toxic effect on the fetus at a particular phase of development resulting in a fetal malformation.
  • veterinary prescription d. a drug that may not be dispensed without the prescription of a licensed veterinarian and that bears the label statement: “CAUTION: Federal law restricts this drug to use by or on the order of a licensed veterinarian.”

• drug-induced any effect, whether intended or unexpected, beneficial or detrimental, that is caused by the administration of a drug. See also iatrogenic.

• drug–nutrient interaction alterations in nutritional status can affect drug metabolism; some drugs can affect nutritional status.

• druggist [drug′ist] pharmacist; chemist.

• drumstick [drum′stik] a spherical shape with a single, long extension or conversely, a long stick with a knob on the end.

  • d. lobe a lobe attached by a thin strand of nuclear membrane to the nucleus of a varying percentage of neutrophils in females. Contains the Barr body. Called also sex bud.
  • d. spore the characteristic spherical, terminal spore of Clostridium tetani.

• drunken horse grass Achnatheruminebrians.

• druse crystals a crust of small crystals lining the sides of a cavity.

• drusen [droo′z n] 1. hyaline excrescences in Bruch’s membrane, particularly of primates; usually due to aging. 2. rosettes of granules occurring in the lesions of actinomycosis. Called also sulfur granules.

• dry [dri] a state of dehydration or relative deficiency of water.

  • d. bench 1. that part of a radiographic dark room where film and cassettes are handled, i.e., there is no chance of film being contaminated by chemicals. 2. a slang expression for simulated research work, for reported experiments that were not actually done.
  • d. cow see dry cow.
  • d. ice solidified carbon dioxide; in an icebox, it produces temperatures of about −76°F (−60°C).
  • d. lot livestock, usually cattle, are kept in a small area with a firm floor but no roof or walls. All food and water are brought to them. Refers usually to dairy herds. See also feedlot.
  • d. mash a method of feeding poultry. Essentially a mixture of grain and supplements.
  • d. sow house/room area where sows are housed and fed between mating and farrowing. Called also gestation barn.

• dry coat see anhidrosis.

• dry cow one not lactating.

  • close up d.c. a cow approximately 2 weeks from calving, usually housed separately to facilitate different feeding and close to the milking parlor so there is easy and frequent observation.
  • far-off d. c. cows more than 2 weeks from calving.

• dry herd see dairy herd.

• dry matter (DM) plant or animal tissue residue after it has been heated to a constant weight and all of the moisture in the sample has been driven off by gentle heat.

  • d. m. basis a method of expressing the concentration of a nutrient or poison in a feed, by expressing its concentration in terms of the dry matter content.
  • d. m. intake the feed intake, usually per day, expressed in terms of its dry matter content. Dry matter intake is the most critical factor in evaluating nutritional adequacy of a diet but is difficult to determine in group feeding situations.

• dry period the period during the lactation cycle when the cow is not lactating, i.e., the period between the end of one lactation and the beginning of the next.

  • d. p. colostrum see dry period secretion (below).
  • d. p. secretion after lactation ceases in normal cows the milk in the udder changes to a thin watery fluid, then disappears altogether in some, then a thick, honey-like secretion appears, then to a very thick opalescent colostrum and finally the normal custard-like colostrum.
  • d. p. treatment treatment of the udder of dairy cows during the dry (nonlactating) period. This is an important part of most bovine mastitis control programs in the removal of subclinical infections that have established during the lactation, and reduction of new infections occurring during the dry period. This is effected by treating each quarter of the udder with a long-acting, broad-spectrum antibiotic preparation immediately after the last milking of a lactation. The strategy is highly effective against the common contagious bacterial causes of mastitis, including Staphylococcus aureus, Streptococcus agalactiae. Most control programs treat all quarters of all cows at drying off (blanket treatment); some treat only infected quarters (selective treatment).

• dry sheep equivalent (DSE) a unit of animal feed based on how much more or less feed each animal requires compared with that required by one dry (not lactating) sheep. The same system can be used to estimate the nutritive value of a paddock of pasture or a shed full of hay. Based on the figure of a daily requirement for 7.2 megajoules of metabolizable energy for a 2-year-old dry sheep weighing 45 kg; e.g., a dairy cow milking 20 kg milk/day has a dry sheep equivalent of 23; a beef calf of 200-kg body weight has a DSE of 4.

• dryfarming farming without the aid of irrigation.

• drying off the management technique of ceasing to milk cows that are still lactating. Dairy herd management is greatly facilitated if cows can be dried off abruptly when the milk yield has fallen below a profitable level or the ensuing parturition is close. Cows with subclinical mastitis are likely to suffer an attack of clinical mastitis if milking is ceased abruptly, especially if the milk yield is still high. The risks of new infections during the dry period are also greater with abrupt drying off, and this may be significant if the prevalence of quarter infection in the herd is high. Precautions against these problems include a short period of once-daily milking and severe restriction of food and water intake and use of dry period treatment. Another problem arising at drying off, or at cessation of milking to improve the appearance of the cow, is that of anaphylaxis or milk allergy. This takes the form of urticaria and dyspnea about 24 hours after milking is stopped.

  • d. o. anaphylaxis see milk allergy.
  • d. o. chronic quarters infusion of an escharotic agent, e.g., silver nitrate, copper sulfate solution into the individual chronically affected quarter, leaving it for a short period, then evacuating the quarter and if necessary perfusing it with normal saline.

• drylot see dry lot.

• Drymaria a plant genus of the family Caryophyllaceae; contain an unknown toxin which causes tremor, diarrhea and liver and kidney lesions. Includes D. arenarioides (alfombrilla), D. cordata, D. diandra (tropical chickweed), D. pachyphylla (drymary).

• drymary Drymariapachyphylla.

• Dryopteris [dri-op′t -ris] a genus of the fern family Aspleniaceae; rhizomes contain a toxin thought to be a thiaminase and which causes somnolence, stumbling gait and blindness due to encephalopathy in sheep and cattle. Includes D. affinis (D. borreri), D. carthusiana (buckle fern), D. filix-mas. Called also male fern.

• Drysdale New Zealand carpetwool sheep derived from Romney Marsh by mutation; wool fiber diameter 35–45 microns, white face and dark hooves; rams are horned, ewes polled.

• Ds chemical symbol, darmstadtium.

• ds double-stranded; used in reference to nucleic acid.

• dsDNA double-stranded DNA.

• DSE dry sheep equivalent.

• DSH domestic shorthair (cat).

• DSMA disodium monomethanearsonate; once used organic arsenical herbicide. Can cause poisoning similar to inorganic arsenic. See also arsenic poisoning.

• dsRNA double-stranded RNA.

• DSS dioctyl sodium sulfosuccinate.

• DTH delayed type hypersensitivity.

• DTIC dacarbazine.

• DTM dermatophyte test medium.

• DTPA diethylenetriamine penta-acetic acid.

• Du Mai see Governing Vessel.

• dual-purpose applies to any animal but usually refers to cattle (meat and milk), sheep (wool and meat) and fowl (eggs and meat). Dual-purpose cattle breeds include Dairy shorthorn, Dexter, Meuse-Rhine-Yssel, Red poll Simmental, South Devon, and welsh black.

• dubbing see decombing.

• dubnium (Db) a chemical element, atomic number 105, atomic weight 262.

• Dubin–Johnson syndrome [doo′b n jon′s n] hereditary chronic nonhemolytic jaundice thought to be due to defective excretion of conjugated bilirubin and certain other organic anions by the liver; a brown coarsely granular pigment in hepatic cells is pathognomonic. A very similar disease occurs in Corriedale and Southdown sheep. See also inherited photosensitization.

• Duboisia [doo-boi′se- ] Australian genus of the plant family Solanaceae.

  • D. hopwoodii contains the piperidine alkaloids nicotine and nor-nicotine. Called also pituri, pitchery.
  • D. leichhardtii, D. myoporoides contain pyridine alkaloids, e.g., hyoscine, hyoscyamine, with atropine-like actions. Poisoning signs include somnolence, tremor, thirst, dilatation of pupil, and incoordination. Called also corkwood.

• Duchenne dystrophy [du-shen′] see Duchenne muscular dystrophy.

• duck [duk] a member of the family Anatidae that includes many genera of ducks, geese and swans. See Anas platyrhynchos, Aylesbury, Rouen, Indian runner, Khaki Campbell, Pekin, Muscovy.

  • d. bush, d. plantGomphocarpus physocarpus. See also Asclepias.
  • d. virus hepatitis a highly contagious and fatal disease of young ducklings caused by duck hepatitis Avirus type 1 (DHAV-1) in the genus Avihepatovirus. Affected ducklings are lethargic, incoordinate, and rapidly develop convulsions. The disease is characterized by hepatitis of sufficient severity to kill the birds within a few hours of signs of illness first being observed. A disease notifiable to the OIE (see Table 20).
  • new d. disease see Riemerella anatipestifer.
  • d. plague see duck plague.
  • d. septicemia see Riemerella anatipestifer.
  • d. sickness type C botulism.
  • d. virus enteritis see duck plague.

• duck-billed platypus see platypus.

• duck egg drop syndrome virus (DEDSV) a newly emerging pathogenic flavivirus isolated from ducks in China that causes in severe egg drop syndrome in domestic poultry.

• duckling [duk′ling] baby duck.

• duckmole see platypus.

• duct [dukt] a passage with well-defined walls, especially a tubular structure for the passage of excretions or secretions. See also ductus.

  • accessory pancreatic d. the duct of the dorsal pancreatic primordium that opens on the minor duodenal papilla. Called also Santorini’s duct or duct of Santorini.
  • allantoic d. see urachus.
  • alveolar d. one of the final branches of the bronchial tree consisting of a tube whose walls are composed of alveoli.
  • bile d., biliary d. the passages for the conveyance of bile in and from the liver. See also bile duct.
  • cochlear d. an endolymph-filled spiral membranous tube in the bony canal of the cochlea that separates the scala tympani below, the scala vestibuli above, and that begins in a blind extremity (the vestibular caecum) and contains the spiral organ of Corti in its floor.
  • common bile d. a duct formed by the union of the cystic and hepatic ducts. See also bile duct.
  • cystic d. the passage connecting the gallbladder neck and the bile duct.
  • efferent d. any duct that gives outlet to a glandular secretion.
  • ejaculatory d. the duct formed by union of the ductus deferens and the duct of the vesicular glands (seminal vesicles), opening into the prostatic urethra on the colliculus seminalis. Found in the horse and ruminants.
  • endolymphatic d. a canal connecting the membranous labyrinth of the ear with the endolymphatic sac.
  • epididymal d. developed from the first part of the mesonephric duct.
  • excretory d. one through which the secretion is conveyed from a gland.
  • d. of Gartner see Gartner’s ducts.
  • hepatic d. the excretory duct of the liver, or one of its branches in the lobes of the liver. See also bile duct.
  • incisive d. one of a pair of ducts perforating the palate and that communicate between the mouth and the vomeronasal organ within the nasal cavity; they are thought to conduct chemicals for olfactory appraisal by the vomeronasal organ.
  • intralobar d. ducts within lobes that provide drainage for secretions of lobes of glands.
  • intralobular d. ducts found within lobules that provide drainage for secretions of lobules of glands.
  • lacrimal d. one of the excretory ducts of the lacrimal gland. See also lacrimal apparatus.
  • lacrimonasal d. nasolacrimal duct.
  • lactiferous d. ducts conveying the milk secreted by the lobes of the mammary gland to the lactiferous sinuses or to the teats.
  • lobar d. drains the secretions from the lobes of gland, connecting with the main excretory duct.
  • lobular d. drains the secretions of lobules of glands.
  • lymphatic d. any of the larger lymph drainage vessels, e.g., thoracic duct.
  • lymphatic d. (left) thoracic duct.
  • lymphatic d. (right) a vessel draining lymph from the cranial right side of the body, receiving lymph from the right subclavian, jugular and mediastinal trunks when those vessels do not open independently into the right brachiocephalic vein.
  • mammary d. lactiferous ducts.
  • mandibular d. drainage duct of the mandibular salivary gland.
  • mesonephric d. see mesonephric duct.
  • metanephric d. the embryonic ureter.
  • müllerian d. see müllerian duct.
  • nasal d. see nasolacrimal duct (below).
  • nasolacrimal d. the tear duct leading from the lacrimal sac to open on the floor of the nasal vestibule. See also lacrimal apparatus.
  • nasopalatine d. see incisive duct (above).
  • pancreatic d. the main excretory duct of the pancreas, which usually opens with the bile duct on the major duodenal papilla; may be a single duct, or two ducts that join, or two independent ducts opening into opposite sides of the intestine. See also bile duct. Called also Wirsung’s duct.
  • papillary d’s (kidney) the straight excretory or collecting portions of the renal tubules, which descend through the renal medulla to a renal papilla or renal crest.
  • papillary d. (teat) the duct leading from the teat sinus to the exterior; see teat canal.
  • paramesonephric d. müllerian duct.
  • parotid d. the duct by which the parotid gland empties into the mouth vestibule opposite the upper molars. See also parotid glands.
  • perilymphatic d. see aqueduct of cochlea.
  • pronephric d. the early embryonic duct from the primitive kidney which leads into the mesonephric duct in the embryo’s later stages.
  • prostatic d’s minute ducts from the prostate, opening into or near the prostatic sinuses on the dorsal wall of the urethra.
  • salivary d’s the ducts of the salivary glands.
  • semicircular d’s the long ducts of the membranous labyrinth of the ear.
  • sublingual d. the excretory ducts of the sublingual salivary glands.
  • submandibular d. the duct that drains the submandibular gland and opens at the sublingual caruncle. Called also submaxillary duct.
  • submaxillary d. submandibular duct (above).
  • tear d. nasolacrimal duct.
  • thoracic d. a duct beginning in the cisterna chyli and emptying into the venous system at the junction of the left subclavian and left jugular veins. It acts as a channel for the collection of lymph from the portions of the body caudal to the diaphragm and from the left side of the body cranial to the diaphragm.
  • thyroglossal d. the transient, non-patent duct, from the thyroid gland to the floor of the pharynx that is the legacy of the development of the thyroid from the floor of the pharynx.
  • vitelline d. see Meckel’s diverticulum.

• ductile [duk′til] susceptible of being drawn out without breaking.

• ductless [dukt′l s] having no excretory duct.

  • d. glands the endocrine glands.

• ductule [duk′tūl] a minute duct.

  • efferent d’s. drainage pathways from the rete testis that pierce the testicular capsule and join the head of the epididymis.

• ductuli biliferi smaller bile ducts accompanying the branches of the portal vein.

• ductuli efferentes connect the rete testis with the ductus epididymis.

• ductulus [duk′tu-l s] pl. ductuli [L.] ductule.

• ductus [duk′t s] pl. ductus [L.] duct.

  • d. arteriosus a fetal blood vessel that joins the aorta and pulmonary artery. Abnormal persistence of an open lumen after birth results in a patent ductus arteriosus. Called also persistent or patent ductus arteriosus.
  • d. choledochus see bile duct.
  • d. deferens the excretory duct of the testis, which is a continuation of the epididymal duct and which in horses and ruminants joins the excretory duct of the vesicular gland (seminal vesicle) to form the ejaculatory duct; called also vas deferens.
  • d. epididymis the duct that, in combination with connective tissue and muscle, forms the head, body and tail of the epididymis and continues as the ductus deferens.
  • d. epoophori longitudinales see Gartner’s ducts.
  • d. reuniens the joining channel between the cochlea and sacculus of the membranous labyrinth of the inner ear.
  • d. venosus a major blood channel that develops through the embryonic liver from the left umbilical vein to the caudal vena cava and closes within a few days after birth. If it remains patent, a congenital portacaval anastomosis is created. See patent ductus venosus.

• Dudley nose lay term for nasal depigmentation.

• Dugaldia hoopesii Heleniumhoopesii.

• dugaldin a toxic glycoside in Helenium.

• Dugbe orthonairovirus a tickborne bunyavirus infection of cattle in West Africa; related to Nairobi sheep disease virus.

• dugite see brown snake.

• dugong a herbivorous marine mammal (Dugong dugon), the only member of the family Dugongidae. Massive (10–13 ft long, weighing 600 lb) with a fusiform silhouette, well-developed forelimbs, but no hindlimbs or dorsal fin.

• DUIB di-ureido isobutane.

• duiker, duyker small to medium (up to 50 lb) African antelope with short, straight horns; includes Cephalophus and Philantomba spp. and Sylvicapra grimmia (common duiker).

• dulaa a saclike pouch of the soft palate, capable of being inflated, everted through the mouth and gargled through by the male camel when in rut. Also called a gulah

• Dulbecco’s medium [dool-bek′o] a phosphate-buffered saline solution used for embryo collection in a variety of species.

• dullness [dul′nis] 1. a quality of sound elicited by percussion, being short and high-pitched with little resonance. 2. a state of consciousness in which the animal’s movements are sluggish and its response to external stimuli is one of indifference.

  • cardiac d. the area of the precordium over which a dull percussion sound is elicited.

• dumb [dum] mute. Commonly said of animals generally, but they do have the capacity for vocal communication

• dumbcane Dieffenbachia seguine.

• dumdum fever [dum′dum] see leishmaniasis.

• dummy [dum′e] state of depressed consciousness in which the still mobile animal walks continuously and compulsively, head down, stumbling gait, walking into fixed objects, head presses when it meets a fixed object, when trapped in a narrow place is incapable of backing out, walks into human habitation that it would ordinarily shun. May walk in circles. Does not respond to ordinary stimuli, does not eat or drink. Caused by encephalitis, hepatic encephalopathy, subacute lead poisoning. Called also blind staggers, dummy syndrome, neonatal encephalopathy. See also neonatal maladjustment syndrome.

  • d. calf syndrome thought to be a behavior problem inherited in some breeds; the newborn calf is bright and alert but lacks teat seeking and teat sucking reflexes.
  • d. disease said of lambs born with hydranencephaly due to intrauterine infection with bluetongue virus, usually the vaccine strain.

• dumping [dump′ing] 1. shortening the toe of the hoof by rasping down the outside wall; creates a weakness of the wall and is a defect in a shod horse. 2. heavy mechanical compression of a standard bale of wool to about half of its normal size and clamping by metal bands; used to facilitate export shipment.

• dumping syndrome [dump′ing] a complex of abnormal vasomotor signs associated with eating and the rapid emptying of hyperosmolar gastric contents into the proximal small intestine; believed to be due to the shift of fluid into the gut lumen, intestinal distention, and contraction of plasma volume.

• DUMPS a lethal inherited disorder of Holstein and Japanese Black cattle that causes infertility. The name is an acronym of Deficiency of Uridine MonoPhosphate Synthetase, the enzyme that participates in the reaction that converts orotate to uridine 5′-monophosphate. Individuals having the homozygous recessive genotype die at about 40 days of gestation.

• dun a coat color, generally a yellow varying from gray-yellow to light yellow, always with a brown stripe from the wither to the tail butt.

• Duncan applicator [dung′k n] a device used for the control of ticks in game animals; as the animal licks bait feed in the center of the device it receives a dose of pour-on insecticide.

• dung [dung] feces. Called also manure, droppings, scat.

• Dunker a medium-sized scenthound, popular in Norway. It is a powerfully built dog with a short coat, pendulous ears, and long tail. The short coat may be tan with black saddle and white markings, or the black may be splotched (merled). Called also Norwegian hound.

• dunkop the pulmonary form of African horse sickness.

• dunnart (Sminthopsis spp.) small, mainly insectivorous dasyurid marsupials, native to Australia and Papua New Guinea.

• duodenal [doo″o-de′n l, doo-od′-n l] of or pertaining to the duodenum.

  • d. glands glands in the submucosa of the duodenum, opening into the small intestine; called also Brunner’s glands.
  • d. reflux retrograde movement of duodenal contents, either into the stomach where it has been incriminated as a cause of vomiting and gastric hyposecretion, or into the pancreatic duct and parenchyma as a factor in the etiology of acute pancreatitis.
  • d. ulcer peptic ulcer of the duodenum. See also ulcer.

• duodenectomy [doo″o-d -nek′t -me] excision of the duodenum, total or partial.

• duodenitis [doo-od″ -ni′tis] inflammation of the duodenum. A cause of colic in horses. In cattle, occurs from damage caused by the migration of the young amphistomes from the duodenum in infestations with Calicophoron spp. See paramphistomiasis, equine duodenitis-proximal jejunitis.

• duodenocholedochotomy [doo″o-de″no-ko″led-o-kot′ -me] incision of the duodenum and common bile duct.

• duodenoenterostomy [doo″o-de″no-en″t r-os′t -me] anastomosis of the duodenum to some other part of the small intestine.

• duodenography [doo″o-d -nog′r -fe] radiography of the duodenum.

• duodenohepatic [doo″o-de″no-h -pat′ik] pertaining to the duodenum and liver.

• duodenoileostomy [doo″o-de″no-il″e-os′t -me] anastomosis of the duodenum to the ileum.

• duodenojejunostomy [doo″o-de″no-j -joo-nos′t -me] anastomosis of the duodenum to the jejunum.

• duodenorrhaphy [doo″o-d -nor′ -fe] suture of the duodenum.

• duodenoscopy [doo″o-d -nos′k -pe] endoscopic examination of the lumen of the duodenum.

• duodenostomy [doo″o-d -nos′t -me] surgical formation of a permanent opening into the duodenum. May be for the purpose of introducing a tube for post-pyloric feeding.

• duodenotomy [doo″o-d -not′ -me] incision of the duodenum.

• duodenum [doo″o-de′n m, doo-od′-n m] the first or proximal portion of the small intestine, extending from the pylorus to the jejunum. It plays an important role in digestion of food because the bile and pancreatic ducts empty into it. See also digestive system.

• duplex DNA double-stranded DNA. See deoxyribonucleic acid.

• duplication [doo″plľ-ka′sh n] a doubling; in genetics, the presence of an extra segment of chromosome.

• dupp a syllable used to represent or mimic the second sound heard at the apex of the heart in auscultation. See also heart sounds.

• dura mater [doo′r ma′t r] [L.] the outermost, toughest and most fibrous of the three membranes (meninges) covering the brain and spinal cord.

• dural [doo′r l] pertaining to the dura mater.

  • d. ossification see dural ossification.
  • d. sinuses, d. venous sinuses venous spaces between the layers of dura that collect cerebrospinal fluid and return it to the vascular system.

• durango root see Datisca glomerata.

• Duranta erecta an American plant in the family Verbenaceae; fruits and leaves contain unidentified toxins causing tetanic seizures and enteritis in mammals and birds. Called also D. repens, pigeonberry, golden dewdrop, Sheena’s gold, Geisha girl.

  D-42.

  

  Duroc pig.

• Durham tube [door′ m] an inverted glass tube in bacterial carbohydrate fermentation tests. Used to detect gas production.

• Durikainema macropi a nematode parasite of the superfamily Muspiceoidea found in the venous system of some kangaroo species.

• Durham’s tube [door′ m] a jointed tracheotomy tube.

• duroarachnitis inflammation of the dura mater and arachnoid.

• Duroc Jersey red pigs with prick ears lopped over halfway up. Produced by the merging of two breeds, Duroc and Jersey, in the US. Called also Duroc.

• durotomy incision of the dura mater.

• durum a class of awned hard wheat that refers to the resistance of the grain to milling. Used for pasta.

• dust [dust] heavy dust such as in dust storms or volcanic fallout may contaminate animal feed sufficiently to cause sand colic in horses. Ruminants seem not to be much affected.

  • d. balls equine intestinal foreign bodies composed of plant fibers with a superficial coating of dense minerals. Because of their light weight they are often evacuated with the feces.
  • d. inhalation important risk factor in etiology of coccidioidomycosis (corral dust), chronic obstructive pulmonary disease in horses (feed dust in stables).
  • d. rhinotracheitis dusty feed fed in a confined space such as a stable can cause chronic coughing due to rhinotracheitis in cattle.

• dusting powders [dus′ting] a popular form of applying antibacterial substances to wounds and external parasiticides to the skin in animals.

• dusty miller Seneciocineraria.

• Dutch black pied cattle black and white dual-purpose cattle from Holland.

• Dutch rabbit a very hardy, trouble-free, small (less than 5 lb), breed of rabbits with a dense coat of fine fur; white saddle, feet and face markings, and almost any other color elsewhere, including tortoiseshell, chocolate and yellow.

• Dutch sheepdog see Schapendoes.

• dutchman’s breeches Dicentracucullaria, D. spectabilis, Thamnosmatexana.

• dutchman’s pipe Aristolochia spp.

• Duttonella [dut″o-nel′ ] a subgenus of the genus Trypanosoma. Includes T. vivax and T. uniforme.

• Duvenhage virus a member of the Lyssavirus genus, isolated from fruit-eating bats in which it causes a disease similar to rabies.

• Duverny’s glands [du-v r-na′] see Bartholin’s glands.

• DV dorsoventral.

• DVM Doctor of Veterinary Medicine.

• dwarf [dworf] an abnormally undersized animal or plant. See also dwarfism.

  • d. bay Daphnemezereum.
  • d. cattle see dwarfism.
  • dolichocephalic d. dwarf with a long, narrow head.
  • long-nosed d. homozygous recessive dwarf defect in American Angus cattle in which affected calves have shortened limbs but normal body size, diminished endochondral ossification, and premature calcification of chondrocytes. Called also long-headed dwarf.

• dwarfing genes alleles at different loci in chicken chromosomes that generate chickens with a much lower body weight at maturity.

• dwarfism [dworf′iz- m] the state of being a dwarf; underdevelopment of the body. Dwarfism may be the result of a developmental anomaly, of nutritional or hormone deficiencies, or of other diseases. See also achondroplasia, cretinism.

  • achondroplastic d. an inherited defect in cattle caused by defective cartilage growth that is effectively lethal because the calves do not grow well and die before 6 months of age. Typical signs are short legs, large, wide, short head, protruding lower jaw, depression of the maxilla with obstruction of respiration, and stertorous breathing. The tongue protrudes and the eyes bulge, the abdomen is distended, and there is chronic bloat. Urine concentrations of glycosaminoglycans are much higher than normal in some of the calves. Called also snorter dwarfs. The condition has also been seen in dogs and cats. See also achondroplasia.

    D-43.

    

    Six-month-old male German shepherd dog with pituitary dwarfism.

  • chondrodystrophic d. with hydrocephalus see bulldog calves.
  • constitutional d. a proportional dwarfism due to a generalized genetic defect.
  • disproportionate d. the skeleton is dystrophic, the soft tissues are normal. The animal is pot-bellied, dyspneic, and the tongue protrudes. Characteristic of achondroplastic and chondrodystrophic dwarfs.
  • German shepherd dog d. an autosomal recessive inherited juvenile panhypopituitarism, caused by a mutation in the LHX3 gene, resulting in deficiency of all anterior pituitary hormones except ACTH. Affected puppies appear normal at birth but soon show a reduced rate of growth, retention of deciduous teeth and puppy hair, alopecia, delayed closure of epiphyseal growth plates, infantile genitalia, and shortened life span.
  • pituitary d. see German shepherd dog dwarfism (above).
  • primordial d. general proportional dwarfism of all organs of the kind that has produced Kerry cattle and Miniature pinschers.
  • proportional d. a recently described congenital miniature condition in Angus and Angus crossbred cattle, characterized by extremely small stature and proportionate growth. Inherited in a dominant manner with incomplete penetrance. See also primordial dwarfism (above).
  • thyroid d. hypothyroidism in an immature animal causes retarded growth and development of bones with disproportionate dwarfism. See cretinism.

• dwarfism–joint hypermobility inherited disproportionate dwarfism in some cattle breeds with abnormal joint mobility caused by a collagen defect in joint cartilage.

• dwelling an abnormality of gait in a horse in which there is a momentary hesitation before the foot is placed on the ground.

• Dx abbreviation for diagnosis; used in medical records. See DDx.

• DXA duel energy x-ray absorptiometry; a form of x-ray technology used most commonly to measure bone mineral content (density), but also used in small animals to measure total body composition, ie fat and lean body mass.

• Dy chemical symbol, dysprosium.

• dyclonine hydrochloride [di′klo-nēn] a bactericidal and fungicidal topical anesthetic agent.

• dye [di] any of various colored substances containing auxochromes and thus capable of coloring substances to which they are applied; used for staining and coloring, as test reagents, and as therapeutic agents.

  • acridine d. acriflavine and proflavine are antiseptic dyes.
  • azo d. dyes like scarlet red and phenazopyridine are used as antiseptics to be applied topically or as urinary antiseptics.
  • diagnostic d. several diagnostic test procedures involve the administration of a dye and determination of the rate of excretion, either by measuring concentrations remaining in the body or amounts excreted in the urine, feces, etc.
  • d. dilution method the standard method of measuring circulating plasma or extracellular fluid volume; based on the degree of dilution of a physiologically inert dye, such as Evan’s Blue dye (T-1824), sodium thiocyanate or inulin, injected intravenously.
  • vital d. see vital stain.

• dynamics 1. the scientific study of forces in action; a phase of mechanics. 2. the motivating or driving forces, physical or moral, in any field.

• dynamite a commercially available explosive containing ammonium nitrate, which has caused nitrate poisoning in cattle.

• dynamization a strategy for promoting bone healing in fractures by allowing some movement or compressive loading. Usually achieved by the removal of some pins from an external fixator.

• dynamograph [di-nam′o-graf] a self-registering dynamometer.

• dynamometer [di″n -mom′-t r] an instrument for measuring the force of muscular contraction.

• dyne [dīn] the metric unit of force, being that amount that would, during each second, produce an acceleration of 1 cm/s in a particle of one gram mass.

• dynein [di′nēn] group of motor proteins in cells that uses energy from ATP to produce movement. Axonemal dyneins are found in the axonemes of cilia and flagella and cause motility by enabling the sliding of microtubules in these structures. Cytoplasmic dyneins are found in all animal cells and are involved in organelle transport and centrosome assembly.

• dynorphins [di-nor′finz] a family of endogenous opioid peptides associated with inhibition of excitatory neurotransmission.

• dyphylline [di′f l-in] see diprophylline.

• dys- word element. [Gr.] bad, difficult, painful, disordered.

• dysadrenalism, dysadrenia [dis″ -dren′l-iz- m] any disorder of adrenal function, whether of decreased or heightened function.

• dysarthrosis [dis″ahr-thro′sis] 1. deformity or malformation of a joint. 2. dysarthria.

• dysautonomia [dis″aw-to-no′me- ] dysfunction of the autonomic nervous system characterized by constipation, megaesophagus with regurgitation, dilated pupils, protrusion of the nictitating membranes, dry nasal and buccal mucosae, reduced laryngeal secretions and bradycardia. Seen in cats, dogs, horses, and rabbits, more commonly in the UK and US. The cause is unknown, although a toxicoinfection with Clostridium botulinum Type C has been proposed. Called also Key-Gaskell syndrome, feline dysautonomia, canine dysautonomia, grass sickness, dilated pupil syndrome, feline autonomic polyganglionopathy.

  • equine d. see grass sickness.

• dysbacteriosis 1. possibly a bacterial disease; classified as a bacterial disease but its authentication is dubious. 2. Disease caused by an imbalance of the normal flora of the organ or part of the organ.

• dysbarism [dis′b r-iz- m] any clinical syndrome caused by difference between the surrounding atmospheric pressure and the total gas pressure in the various tissues, fluids, and cavities of the body, including such conditions as barosinusitis, barotitis media, or expansion of gases in the hollow viscera.

• dysbasia [dis-ba′zh ] difficulty in walking, especially that due to a nervous lesion.

• dysbetalipoproteinemia [dis-ba″t -lip″o-pro″te-ne′me-] the accumulation of abnormal β-lipoproteins in the blood.

• dyscephaly [dľ-sef′ -le] malformation of the cranium and bones of the face.

• dyschezia [dis-ke′zh ] difficult or painful evacuation of feces from the rectum. Characteristic of distal colonic or rectal disease.

• dyschondroplasia [dis″kon-dro-pla′zh ] see enchondromatosis.

  • tibial d. a mass of hypertrophic cartilage develops in the proximal end of the tibiotarsal bone in young broilers and turkeys. May cause lameness and limb deformity.

• dyschromia [dis-kro′me- ] any disorder of pigmentation of the skin or hair.

• dyscoria [dis-kor′e- ] abnormal shape or form of the pupil.

• dyscorticism [dis-kor′tľ-siz- m] disordered functioning of the adrenal cortex.

• dyscrasia [dis-kra′zh ] a morbid condition, usually referring to an imbalance of component elements.

  • blood d. any abnormal or pathological condition of the blood.
  • bone marrow d. see bone marrow dyscrasia.

• dysecdysis [dis-ek′dľ-sis] abnormal shedding of the skin of reptiles. In captive reptiles usually due to inadequate or inappropriate husbandry.

• dysembryoma [dis-em″bre-o′m ] see teratoma.

• dysentery [dis′ n-ter″e] any of a number of disorders marked by inflammation of the intestine, especially of the colon, with abdominal pain, tenesmus, and frequent stools often containing blood and mucus. The causative agent may be chemical irritants, bacteria, protozoa, viruses, or parasitic worms. See also lamb dysentery, swine dysentery, winter dysentery, coccidiosis, salmonellosis, canine parvovirus, colitis-X, trichuriasis, Entamoeba histolytica infection.

  • amebic d. see amebic dysentery.
  • swine d. see swine dysentery.

• dyserythropoiesis [dis- -rith″ro-poi-e′sis] abnormal red cell formation with disorderly maturation.

  • d. dyskeratosis–progressive alopecia probably inherited congenital anemia of Polled Hereford cattle.

• dysesthesia [dis″es-the′zh ] 1. impairment of any sense. 2. abnormal perception of a sensory stimulus. Assumed to occur in animals.

• dysfibrinogenemia [dis-fi-brin″o-j -ne′me-] the presence of abnormal fibrinogens in the body. An inherited dysfibrinogenemia occurs in humans and has been reported in a Collie dog and a family of Borzois. The associated bleeding tendency is mild in dogs.

• dysfunction [dis-funk′sh n] disturbance, impairment or abnormality of functioning of an organ.

• dysgalactia [dis″g -lak′te-] disordered milk secretion.

• dysgammaglobulinemia [dis-gam″ -glob″u-lin-e′me-] a selective deficiency of one or more, but not all, class of immunoglobulin. A hereditary dysgammaglobulinemia has been recorded in chickens.

• dysgenesis [dis-jen′ -sis] defective development; malformation.

• dysgenic [dis-jen′ik] genetically harmful, defective, or disadvantageous.

• dysgerminoma [dis″j r-mľ-no′m] a solid, often radiosensitive, malignant ovarian neoplasm derived from undifferentiated germinal cells; the counterpart of seminoma of the testis.

• dysglycemia [dis″gli-se′me- ] any disorder of blood sugar levels.

• dysgnathia [dis-na′the- ] any oral abnormality extending beyond the teeth to involve the maxilla or mandible, or both. See also brachygnathism, prognathism.

• dysgonic [dis-gon′ik] seeding badly; said of bacterial cultures that grow poorly.

• dyshematopoiesis [dis-he″m -to″poi-e′sis] defective formation of elements of the blood.

• dyshesion [dis-he′zh n] 1. disordered cell adherence. 2. loss of intercellular cohesion; a characteristic of malignancy.

• dyshidrosis [dis″hľ-dro′sis] any disorder of the eccrine sweat glands.

• dyshidrosis tropicale see sweating sickness.

• dyskaryosis [dis-kar″e-o′sis] abnormality of the nucleus of a cell characterized by a hyperchromatic nucleus or irregular nuclear chromatin distribution.

• dyskeratoma [dis-ker″ -to′m] a dyskeratotic tumor.

  • warty d. benign proliferation of the epithelium seen in dogs; the lesions are wart-like papules with a hyperkeratotic, umbilicated center.

• dyskeratosis [dis-ker″ -to′sis] abnormal, premature or imperfect keratinization.

• dyskeratotic [dis-ker″ -tot′ik] pertaining to or of the nature of dyskeratosis.

• dyskinesia [dis″kľ-ne′zh ] impairment of the power of voluntary movement.

  • ciliary d. see primary ciliary dyskinesia.
  • paroxysmal d. abnormalities of movement occurring in episodes. Scottie cramp is an example.

• dyslipoproteinemia [dis-lip″o-pro″te-ne′me- ] Any of a range of disorders in blood lipoproteins, including both lower and higher than normal concentrations and abnormalities in the composition of lipoprotein particles. Plays a role in the pathogenesis of cardiovascular disease. Also known as dyslipidemia.

• dyslochia [dis-lo′ke- ] disordered lochial discharge.

• dysmaturity [dis-m - ′ľ-te] the condition of being small or immature for gestational age; said of fetuses that are the product of a pregnancy involving placental dysfunction. See also prematurity and dysmaturity in foals.

  • congenital hypothyroid d. syndrome of foals occurs predominantly in the prairie provinces of Canada and the Pacific Northwest and is manifest by prolonged gestation, dysmaturity, and limb deformity due to delayed ossification of the carpal bones. Histologically, but not grossly, there is thyroid hyperplasia. In Canada, the syndrome has been associated with high nitrate concentrations in feed, but in the western US, epidemiological data suggest it occurs in late-foaling mares and results from ingestion of goitrogenic winter annual mustard species in the latter 3 months of gestation.

• dysmelia [dis-me′le- ] malformation of a limb or limbs due to disturbance in embryonic development.

• dysmetria [dis-me′tre- ] abnormal rate or range of movement of one or more limbs. A characteristic of cerebellar lesions.

• dysmorphism [dis-mor′fiz- m] 1. appearing under different morphological forms. 2. an abnormality in morphological development.

• dysmorphogenesis giving rise to dysmorphism.

• dysmyelination [dis″mi- -lin-a′sh n] see hypomyelination.

  • spinal d. affects American brown Swiss cattle and apparent when the calf is born with lateral recumbency, opisthotonos, and spastic extension of the limbs. Some calves show muscular atrophy.

• dysmyelinogenesis any abnormality of myelin formation. Includes hypomyelinogenesis, as occurs in congenital tremor of piglets, and puppies and calves.

• dysmyelopoiesis [dis-mi″ -lo-poi-e′sis] see myelodysplasia.

• dysmyelopoietic syndromes see myelodysplasia.

• dysmyotonia [dis″mi-o-to′ne- ] muscular dystonia; abnormal tonicity.

• dysodontiasis [dis″o-don-ti′ -sis] difficulty or irregularity in the eruption of teeth.

• dysontogenesis [dis″on-to-jen′ -sis] defective embryonic development.

• dysorexia [dis″o-rek′se- ] impaired or deranged appetite.

• dysostosis [dis″os-to′sis] defective ossification; a defect in the normal ossification of fetal cartilages.

• dysoxia a state in which oxygen availability limits metabolism with an immediate fall in phosphorylation potential.

• dyspancreatism disorder of function of the pancreas.

• dyspepsia [dis-pep′se- ] specifically, impairment of digestion, but commonly applied to subjective feelings of indigestion in humans.

• dysphagia [dis-fa′je- ] difficulty in swallowing.

  • cricopharyngeal d. see cricopharyngeal achalasia.
  • esophageal d. difficulty in swallowing due to esophageal malfunction.
  • gastroesophageal d. impaired passage of the bolus through the caudal esophageal sphincter.
  • neuropathic d. may be caused by lesions of the glossopharyngeal or vagus nerves or associated nuclei of the caudal medulla oblongata.
  • oral d. abnormal prehension and mastication.
  • oropharyngeal d. abnormalities in mastication and pharyngeal contraction may be caused by hypoglossal nerve dysfunction, polyneuropathy, polymyositis, meningitis, brainstem lesions, and generalized neuromuscular disease.

• Dysphania a genus in the plant family Chenopodiaceae; may cause cyanide poisoning. Includes D. glomulifera (red crumbweed), D. rhadinostachya (Chenopodium rhadinostachyum, mouse-tailed crumbweed), D. littoralis (red crumbweed).

• dyspigmentation [dis-pig″m n-ta′sh n] any abnormality of pigmentation of the skin or hair.

• dysplasia [dis-pla′zh ] an abnormality of development; in pathology, a developmental abnormality leading to alteration in size, shape, and organization of adult cells.

  • black hair follicular d. see canine black hair follicular dysplasia.
  • canine hip d. see hip dysplasia.
  • occipital d. congenital enlargement of the foramen magnum dorsally, often asymptomatic but possibly associated with hydrocephalus, cerebellar herniation, or spina bifida in some dogs. Observed most often in toy breeds.
  • vertebral and spinal dysplasia (VSD) inherited congenital defect of Holstein calves characterized by vertebral (specifically tail) deformities and neurological dysfunctions with gait abnormalities of the hind limbs. See also complex vertebral malformation.

• dysplastic [dis-plas′tik] emanating from or pertaining to abnormality of development.

• dyspnea [disp-ne′ , disp′ne-] the sensation of shortness of breath or air hunger. evident in animals as labored or difficult breathing; a sign of a variety of disorders and is primarily an indication of inadequate ventilation or low fraction of oxygen in inhaled air. Manifest as hypoxemia with or without hypercapnia.

  • expiratory d. the dyspnea is primary during the expiratory phase of respiration. Usually associated with lower airway obstruction.
  • inspiratory d. the dyspnea is primarily during the inspiratory phase of respiration. Usually associated with upper airway obstructions and sometimes disorders of the pleura.

• dyspnoea dyspnea.

• dyspoiesis a disorder of formation; as of blood cells.

• dyspragia [dis-pra′je- ] painful performance of any function.

  D-44.

  

  Sixteen-year-old cat with dyspnea and open mouth breathing caused by thoracic effusion due to feline infectious peritonitis.

• dyspraxia [dis-prak′se- ] partial loss of ability to perform coordinated movements.

• dysprosium (Dy) [dis-pro′se- m] a chemical element, atomic number 66, atomic weight 162.50.

• dysproteinemia [dis-pro″tēn-e′me- ] disorder of the protein content of the blood.

• dysraphism [dis-rāf′iz- m] incomplete closure of a raphe, e.g., of the neural tube. The defect may be complete or partial.

  • spinal d. an inherited defect in Weimaraner dogs and reported in many other breeds. From an early age, affected puppies show varying degrees of ‘bunny hopping’, symmetrical and simultaneous use of the back legs, often overextending them before stepping forward. More severe defects have associated musculoskeletal abnormalities and may be a cause of perinatal death. In Weimearaners, inheritance is autosomal recessive; genetic testing for the mutated NKX2-8 gene is available.
  • sternal d. congenital split of the sternum; may be associated with peritoneopericardial diaphragmatic hernia.

• dysrhythmia [dis-rith′me- ] disturbance of rhythm.

  • paroxysmal d. a cardiac rhythm disturbance having a sudden onset and termination.

• dysspermia [dis-spur′me- ] impairment of the spermatozoa or of the semen.

• dysstasia [dis-sta′sh ] difficulty in standing.

• dyssynergia [dis″sin-ur′je- ] muscular incoordination of any cause

  • detrusor urethral d. a disorder of urination caused by a lack of coordination between contraction of the detrusor muscle and relaxation of the urethra; the urine stream is weak and intermittent, with dribbling. Usually idiopathic, occurring primarily in middle-aged, large-giant breed male dogs, but can be neurogenic. Called also detrusor sphincter dyssynergia, reflex dyssynergia, and functional urethral obstruction.

• dystectia [dis-tek′she- ] defective closure of the neural tube.

• dysthrombopoiesis [dis-throm″bo-poi-e′sis] defective platelet formation with morphologic changes evident in the platelets.

• dysthyroid, dysthyroidal [dis-thi′roid, dis″thi-roi′d l] denoting defective functioning of the thyroid gland.

• dystocia [dis-to′sh ] difficult parturition to the point of needing human intervention.

  • fetal d. that due to some condition inherent to the fetus.

    D-45.

    

    Dystocia may damage the dam or the newborn. This calf has swelling of the tongue and face due to prolonged birth while the head was outside the vagina, and will have difficulty nursing the cow and getting an early intake of colostrum. Courtesy O. Szenci.

  • maternal d. that due to some condition inherent in the dam.
  • placental d. difficult delivery of the placenta.
  • d. rate number of assisted births per hundred births.
  • d. risk the incidence of dystocia is enhanced by many factors including inherited large fetal size, especially in some breeds, high feeding level of the dam during pregnancy, inherited small diameter pelvic canal, youth of the dam, male calves compared with females, the occurrence of multiple births, and congenital abnormalities that increase fetal size.

• dystokia dystocia.

• dystonia [dis-to′ne- ] abnormality of muscular tonus; can cause repetitive or twisting movements.

• dystopia [dis-to′pe- ] malposition; displacement.

• dystrophia [dis-tro′fe- ] [Gr.] dystrophy.

  • d. adiposogenitalis see adiposogenital dystrophy.
  • d. epithelialis corneae dystrophy of the corneal epithelium, with erosions.
  • d. ungulae see seedy toe.

• dystrophic [dis-tro′fik] pertaining to or emanating from dystrophia.

  • d. calcification mineralization of soft tissues can occur in hyperadrenocorticism, vitamin D toxicity, and hypervitaminosis A. See also calcification.

• dystrophin [dis′tr -fin] a membrane-associated protein that provides a structural link between the cytoskeleton of a myofiber and the extracellular matrix to maintain muscle integrity, deficient in some types of muscular dystrophy.

• dystrophy [dis′tr -fe] any disorder in which there is chronic and progressive wasting of tissue, usually due to disease, which might be heritable, or defective or faulty nutrition. See also corneal dystrophy, muscular dystrophy.

  • bone d. see osteodystrophia fibrosa, osteomalacia, rickets, osteo porosis.
  • Duchenne d. see Duchenne muscular dystrophy.
  • muscular d. includes enzootic muscular dystrophy of cattle, sheep, pigs, and foals, all of dietary origin, and some probably familial diseases in cattle, sheep, and dogs. See also muscular dystrophy.

• dysuria [dis-u′re- ] painful or difficult urination.

• Dz abbreviation for disease; used in medical records.

• dzo any cross between cattle and yak. Called also zho, zo.