Musculoskeletal and Neurologic Diseases

Ferrets with neurologic, musculoskeletal, or systemic disease may present with rear limb weakness, ataxia/incoordination, or both. Primary neurologic and musculoskeletal disorders are not common in pet ferrets. Clinical signs that appear to be caused by primary neurologic disease, particularly posterior paresis, are frequently manifestations of systemic illness. Therefore a thorough and accurate history and physical examination supported by diagnostic imaging and laboratory testing are essential to establishing a diagnosis, treatment plan, and prognosis. Fracture management is covered in Chapter 33.

Neurologic signs in ferrets are often a result of generalized disease, such as heart failure or hypoglycemia. Thus a general health evaluation is important for all neurologic patients. A common cause of posterior paresis is hypoglycemia secondary to a pancreatic beta-cell tumor, or insulinoma (see Chapter 8). Hypoglycemia can also result from food deprivation or anorexia, vomiting, sepsis, neoplasia, severe hepatic disease, or any metabolic disorder.

Cardiac disease, hypoxia, anemia, and toxin ingestion can result in weakness, ataxia, or central nervous system (CNS) depression.5., 42. Toxicosis from ibuprofen ingestion has been reported to cause neurologic signs including ataxia, depression, coma, and tremors.⁴¹ Clostridium botulinum type C endotoxin causes signs that include dysphagia, ataxia, salivation, and paresis 12 to 96 hours after ingestion of contaminated food; signs can progress to death if the ferret is untreated.¹¹ Proliferative bowel disease has been associated with paresis and ataxia.¹⁴ This may also occur secondary to discomfort and physical obstruction of limb movement from diseases such as splenomegaly, a caudal abdominal mass, inguinal or sublumbar lymphadenopathy, cystic calculi, peritonitis, prostatic enlargement, or urinary obstruction. Urinary and fecal incontinence may accompany posterior paresis if the underlying problem affects the caudal lumbar innervation of these structures.

Posterior Paresis, Ataxia, and Seizures

Posterior Paresis

Posterior paresis is synonymous with rear leg weakness. Generalized weakness in ferrets is often more pronounced in the rear legs and may be mistakenly attributed to primary neurologic disease. A ferret that is weak loses the normal upward arch in its back, so that the long axis of its body becomes parallel to the ground when it is standing or walking.

Ataxia

Ataxia is incoordination; it can be characterized as either cerebellar, vestibular, or proprioceptive. Cerebellar ataxia is caused by a disruption in transmission of sensory impulses from the vestibular system, cerebral cortex, and spinal cord via the cerebellum. Because the cerebellum does not initiate motor activity but rather coordinates it, affected patients will demonstrate abnormal rate, range, or force of movement with intact strength. Paresis is not present with cerebellar dysfunction. Vestibular ataxia occurs when damage or disease affects the vestibular system within the inner ear. Motor activity is not initiated but is refined and coordinated via the vestibular system by controlling muscles used to maintain head position, eye movement, and equilibrium. Dysfunction results in loss of balance; animals often list or fall to one side and may have head tilt. Proprioceptive ataxia is caused by spinal disease, which will result in proprioceptive deficits that can be localized to the affected region of the spinal column. Trauma, intervertebral disk disease, and tumors arising within or compressing the spinal cord or nerves should be considered.³⁵

Seizures

Seizures are a common neurologic presentation in middle-aged and older ferrets. As with paresis and ataxia, the most common cause of seizures is hypoglycemia secondary to insulinoma. Prolonged seizure activity can also result in hypoglycemia. Thus it is important to monitor blood glucose concentration long-term in patients that present with low blood glucose during or shortly after seizure activity. Other potential causes of seizures include toxin ingestion; CNS infection, inflammation, trauma, or neoplasia; and metabolic disturbances such as hepatic or renal failure. Idiopathic epilepsy has not been reported in ferrets.

Diagnosis of Posterior Paresis, Ataxia, and Seizures

Record the medical history and perform a complete physical examination, auscultating carefully for cardiac murmurs or arrhythmias. Ferrets may normally have a respiratory sinus arrhythmia. Palpate for peripheral pulses to evaluate the strength of cardiac contraction and to determine the presence of dropped or extra beats. Check mucous membranes for evidence of cyanosis. Palpate the abdomen carefully to detect discomfort, an abdominal mass, urinary calculi, or a distended urinary bladder. Include evaluation of the spine and neck for pain, fractures, and muscle asymmetry.

Evaluate results of a complete blood count (CBC) and plasma biochemical analysis in any ferret with neurologic signs to rule out a metabolic or infectious component. Check the blood glucose concentration immediately to minimize artifactual decreases caused by faulty sample shipment or failure to separate plasma or serum from red blood cells. Correct any underlying abnormalities and reassess the animal for changes in neurologic status. Perform whole-body radiography and, if you suspect cardiac disease, perform echocardiography.

If you suspect primary neurologic disease, perform a complete neurologic and orthopedic examination³⁵ (Fig. 10-1 ). Characterize the signs as diffuse or focal, acute or chronic, progressive or static; localize the lesion to areas of brain or spinal cord.²⁷ Evaluate reflexes and palpate for spinal cord pain or hyperesthesia. Keep in mind during examination that the ocular menace response in ferrets is normally diminished or absent.

Fig. 10-1.

Neurologic examination checklist for ferrets.

For signs that can be localized to the CNS, perform computed tomography (CT) or magnetic resonance imaging (MRI) if available. Administer an intravenous contrast medium to enhance brain lesions. For CT scanning, use 2.2 mL/kg of 400 mg/mL iodinated contrast medium (iothalamate sodium, Conray 400; Mallinckrodt Inc., St. Louis, MO); for MRI, use 0.2 mL/kg of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA)⁴⁹ (Fig. 10-2 ).

Fig. 10-2.

Magnetic resonance imaging of a ferret with a cervical chordoma of C2-3. The spinal cord is compressed ventrally by the mass (arrow), which also extends into the bones of the skull. A, T1 Saggital view. B, Coronal view. C, Transverse view.

If signs are localized to the spinal column, take spinal radiographs to look for possible fractures or bone abnormalities, such as proliferative or lytic lesions. Myelography is useful for localizing lesions of the spinal cord and determining a site for surgical approach if needed (see Fig. 10-3 ). If possible, perform a spinal tap to obtain a sample of cerebrospinal fluid (CSF) for analysis. Sites for CSF tap and myelography are the atlanto-occipital and the lumbar (L5-L6) regions. Use a 25-gauge spinal needle, as in canine and feline myelography; a suggested contrast medium is iohexol at 0.25 to 0.5 mL/kg⁵⁰ (Fig. 10-4 ). Reference values for CSF fluid analysis are total protein 28 to 68 μg/μL and nucleated cells 0 to 8/μL.³⁷ Some spinal lesions may be amenable to surgical resection or stabilization; many, however, carry a poor prognosis.

Fig. 10-3.

Normal lateral myelogram of a ferret. Contrast can be seen as two parallel lines along the spinal cord.

Fig.10-4.

A, Cerebrospinal tap from the cisterna magna in a ferret. With the ferret in lateral recumbency at the edge of the table, the head is flexed so that the point of the nose is at 90 degrees to the long axis of the body. The wings of the atlas and the point of the occipital condyle are used as landmarks. B, Lumbar cerebrospinal fluid collection at L5-6. Only a few drops can be collected; to maximize the sample, the fluid can be collected directly into a microtainer (C) or hematocrit tube (D).

For clinical signs localized to peripheral nerves or muscular defects, consult with a veterinary neurologist to perform electromyelography (EMG) and nerve conduction velocity (NCV) studies. Although normal values for ferrets have not been published, comparison of values from the contralateral limb (in unilateral disease) or from another, unaffected ferret will aid in interpreting the results. Tensilon testing (edrophonium HCL) and physostigmine testing can be performed in ferrets at standard canine doses (0.1 mg/kg IV).6., 24., 38., 55. Obtain muscle biopsy samples in the same manner as in dogs and cats when indicated.

Treatment of Posterior Paresis, Ataxia, and Seizures

Treatment of posterior paresis, ataxia, and seizures in ferrets is tailored to the diagnosis. Follow the standard treatment regimens used for dogs and cats in managing a similar condition in a ferret.

In any seizing ferret, the initial treatment must be directed toward arresting seizure activity (Fig. 10-5 ). Check the blood glucose concentration immediately in any animal presenting with seizures, ataxia, or other neurologic signs. If the glucose level is lower than 60 mg/dL, give an intravenous bolus of 50% dextrose solution (diluted 1:1 in crystalloid fluid) at a dose of 2 to 5 mL/kg or titrate to effect.¹⁰ Begin a dextrose drip infusion adequate to maintain normoglycemia while further diagnostic testing is done. Some ferrets require as much as 10% dextrose added to intravenous fluids to achieve normoglycemia. Administer prednisone or prednisolone to hypoglycemic patients to enhance hepatic gluconeogenesis and inhibit glycogenolysis. If an insulinoma is suspected, initiate additional therapy as indicated (see Chapter 8).

Fig. 10-5.

Treatment of seizures in ferrets. IV, Intravenous; CRI, continuous rate infusion.

If seizures persist and the blood glucose concentration is normal (or has been restored to normal), begin aggressive seizure management. Administer diazepam (0.5-1.0 mg/kg) intravenously10., 24., 38.; if venous access is not readily available, administer diazepam or midazolam intramuscularly, intranasally (for more rapid absorption), or rectally. Double the dose for rectal or nasal administration.²⁴ Repeat up to three times to arrest seizure activity. If grand mal or focal seizures persist, begin a constant-rate infusion of diazepam (0.1-1.0 mg/kg per hour added to IV fluids) or initiate phenobarbital (2-10 mg/kg per hour) as a constant rate infusion.³⁸ Phenobarbital can also be administered by bolus; use 3 mg/kg slow IV q30-60min up to a total dose of 18 to 24 mg/kg, then 3 to 5 mg/kg q12h.²⁴ Phenobarbital and diazepam can be administered concurrently.³⁸ Propofol can also be added; administer in aliquots of 2 mg/kg to effect, then 6 mg/kg per hour CRI to effect.²⁴ If cerebral edema is suspected, administer dexamethasone (0.2 mg/kg) or prednisone or prednisolone (1 mg/kg IV) and mannitol (0.5-1.0 g/kg IV over 20 minutes).36., 38. Once no seizures have occurred for 12 to 24 hours, taper the diazepam infusion slowly over the next 12 to 24 hours. Once seizures are controlled, use oral phenobarbital (1-2 mg/kg PO q8-12h) if necessary for long-term seizure management.³⁸ Potassium bromide can also be used for seizure control; administer orally at 70 to 80 mg/kg per day if used alone or at 22 to 30 mg/kg per day in combination with phenobarbital.³⁸ Check blood levels of phenobarbital within 2 to 3 weeks after starting therapy; potassium bromide levels may not reach a steady state for 60 to 90 days. Adjust dosages based on blood levels and clinical signs. The use of gabapetin, zonisamide, or levetiracetam has not been described in ferrets to date. Investigate any underlying disease stimulating the seizure activity after the patient is stable.

Physical therapy is an important but often overlooked adjunct treatment. For ferrets with paresis or paralysis and those debilitated or recumbent from seizures or metabolic disorders, begin passive range-of-motion exercises three to four times daily for affected limbs. This is essential to prevent contracture. Gently massage muscles to enhance blood flow. Implement active exercise as early as possible to preserve muscle tone and stimulate neural return.

Spinal Disorders

Aleutian Disease

Ferrets can be infected with Aleutian disease virus (ADV), a parvovirus that infects mink and ferrets (see Chapter 5). The virus is shed in saliva, urine, and feces; infection occurs by inhalation or ingestion. Clinical signs vary from mild incoordination to posterior ataxia, ascending paresis, persistent tremors, and quadriplegia.43., 46. In one outbreak, clinical signs developed as soon as 24 hours or as long as 90 days after exposure.⁴⁶ The most significant biochemical abnormality is a hypergammaglobulinemia, with serum gamma globulin concentrations increased to greater than 20% of the total serum protein concentration. However, not all affected ferrets have high gamma globulin concentrations.43., 48. Histopathologic changes involving the brain and spinal cord include perivascular cuffing with lymphocytes and sometimes plasma cells, nonsuppurative meningitis, astrocytosis, mononuclear cell infiltration, and focal malacia.43., 48.

If you suspect Aleutian disease in a ferret, submit samples for testing by polymerase chain reaction (PCR), enzyme-linked immunosorbent assay (ELISA), or counterimmunoelectrophoresis (see Chapter 5). Tentative diagnosis is based on a positive result of ADV testing, a high gamma globulin concentration, and the presence of compatible clinical signs. Disease is confirmed at necropsy in suspected ferrets by demonstration of the presence of lymphocytic and plasmacytic infiltrates on histologic examination of tissue samples. Some infected ferrets may be asymptomatic but remain persistently infected, or the disease may be self-limiting and nonpersistent.⁴⁸ The overall incidence of Aleutian disease in ferrets appears to be low; in one serologic study of 446 ferrets, the incidence of seropositive animals was 8.5%.⁴⁸ Treatment consists of supportive care and isolation of suspected animals from unaffected ferrets.

Spinal Tumors

Chordomas and Chondrosarcomas

Chordomas are tumors that arise from remnants of notochord.²⁹ In ferrets, these tumors develop most commonly at the tip of the tail,1., 7., 8., 23., 29. but they have also been described in the cervical region.⁵¹ Ferrets with cervical chordoma can present with posterior paresis and ataxia localized to the area of the lesion.⁵¹ In such cases, perform spinal radiography and myelography to identify a site for surgical approach. Depending on location, these tumors may be amenable to surgical resection; however, the one reported case of recurrence and metastasis of a chordoma in a ferret was that of a cervical chordoma that had been surgically excised.⁵¹ In the tail, chordomas appear as lobulated, firm, nonencapsulated, ulcerated masses at or near the last caudal vertebra. Microscopically, these tumors consist of lobules of physaliphorous cells with areas of well-differentiated bone or cartilage throughout.8., 23., 51.

Chondrosarcoma of the tail has also been described in ferrets.22., 29. Clinical and morphologic descriptions are almost identical to those of chordoma. Differentiation must be made on the basis of immunohistochemical staining, with positive uptake of low-molecular-weight cytokeratin occurring in chordoma but not in chondrosarcoma.8., 23.

In ferrets with any distal tail mass, amputate several vertebrae proximal to the lesion. In cases of chordoma and chondrosarcoma, this is considered curative. Recurrence has not been reported.

Lymphoma

T-cell lymphoma localized to the spine was identified in a ferret presenting with an acute onset of hindlimb paresis, proprioceptive deficits, diminished withdrawal responses, and an atonic bladder. Leukocytosis and lymphocytosis were present, and lysis of the vertebral body was evident radiographically. A mass associated with the soft tissues of the spine was identified by CT scan and ultrasonography. Ultrasound-guided biopsy of the mass confirmed lymphoma. The ferret did not respond to immunosuppressive doses of prednisolone and deteriorated before radiation therapy was initiated.²¹

Fibrosarcoma

Periosteal fibrosarcoma arising from the perivertebral connective tissue was diagnosed in a ferret that presented with hindlimb paralysis.³⁴ Myelography was used to localize the lesion, and a dorsal laminectomy resulted in temporary improvement as well as providing samples for histologic diagnosis. Recurrence of the tumor was evident 35 days after surgery, and metastasis to the lungs was identified.³⁴

Intervertebral Disk Disease

Intervertebral disk disease has been described rarely in ferrets;30., 31. presumably, their long conformation and extreme flexibility of the body and spine may make them more resistant to herniation than other species. In two reports, ferrets with prolapse or herniation of an intervertebral disk presented with paresis or paralysis, accompanied by proprioceptive deficits caudal to the lesion.30., 31. Clinical signs are similar to those seen in other mammals with intervertebral disk disease and may range in severity from mild proprioceptive deficits to complete paralysis. In one case, vertebral subluxation was also present radiographically.³¹ Confirm the diagnosis with myelography; CT and MRI are valuable tests for accurate localization of the lesion and planning of a surgical approach. Surgical decompression is the treatment of choice, and hemilaminectomy was performed successfully in both reported cases.30., 31. Use guidelines for prognosis in disk disease in companion animals based on the presence or absence of deep pain perception and the duration of the clinical signs.

Intracranial Disorders

Canine Distemper

Canine distemper virus in the late stage affects the CNS of ferrets, although initial signs are usually localized to the respiratory and gastrointestinal tracts and the skin (see Chapter 7).¹⁶ Ferrets are highly susceptible to canine distemper virus and may seem to recover from the acute phase, only to die later from the neurotropic form of the disease. Affected ferrets can exhibit salivation, muscle tremors, seizures, and coma.¹⁶ The disease is almost 100% fatal, and infected animals may be a source of infection to other ferrets.¹⁶ Protect ferrets from distemper by vaccination (see Chapter 2).⁵⁴

Rabies

Although reports of rabies in ferrets are rare, ferrets are susceptible to this disease. Clinical signs include hyperactivity, lethargy, paresthesia (exaggerated grooming of a focal area), ataxia, and posterior paresis, sometimes followed by ascending paralysis.16., 32. In experimentally induced rabies in ferrets, the mean incubation period was 28 to 33 days; the mean morbidity was 4 to 5 days.32., 33. In one study virus was detected in the salivary glands of 63% and in saliva of 47% of the rabid ferrets.³³ Suspect rabies in any unvaccinated ferret with clinical signs of neurologic disease and a history of exposure to rabid animals. A killed vaccine is approved for annual vaccination of ferrets (Imrab 3, Rhone Merieux, Athens, GA), but rabies protocol must be followed if the vaccinated animal bites a human (see Chapter 2). Be aware of local or state laws that may affect you or your clients and educate ferret owners at the time of vaccination.

Osteoma

In ferrets, osteomas of the skull can arise from the zygomatic arch, parietal bone, or occipital bone.25., 26., 29., 44. There is also a report of a multilobular osteoma originating from the neck and extending from the base of the skull to the fifth cervical vertebra, causing extradural compression of the spinal cord.²⁰

An osteoma presents as a firm, dense, bony mass arising from one of the bones of the skull. Although these are benign neoplasms, clinical signs are related to physical displacement or compression of normal structures.25., 26., 29., 44. Obtain radiographs of any bony swelling to evaluate the extent of the lesion and the bone of origin. Biopsy may be difficult without surgical removal of the mass because of the extreme density of the tumor. The Jamshidi needle biopsy technique has been described.³⁹ Histopathologic evaluation usually reveals compact lamellar bone, bony trabeculae, and mild to moderate osteoblastic and hematologic activity.25., 26., 44. Surgical removal is the treatment of choice and is usually curative if excision is complete.²⁶

Primary Neoplasia of the Central Nervous System

Although primary tumors of the CNS are uncommon overall, several recent case reports have documented neoplasms of the brain. One primary CNS neoplasm reported in a ferret was a granular cell tumor (sometimes called myoblastoma) in the cerebrum. Presenting signs included progressive head tilt, ataxia, and circling, followed by refractory seizures.⁴⁵ There is also a report of a choroid plexus papilloma originating from the fourth ventricle in a ferret.⁴⁷ This ferret presented with central vestibular signs including head tilt, circling, ataxia, hemiparesis, and loss of proprioception on the ipsilateral side of the lesion. Diagnosis of a mass in this case was made by the use of contrast-enhanced CT scanning and was histologically confirmed at necropsy.⁴⁷ Consider intracranial neoplasia in a ferret with lateralizing progressive CNS signs or seizures and confirm with contrast CT or MRI imaging if available.

Neuronal Vacuolation

Neuronal vacuolation was reported in one ferret that presented with rapidly progressive convulsions and incoordination. Although this is a change associated with transmissible spongiform encephalopathies, the case was ultimately confirmed to be a primary neuronal vacuolation; transmissible spongiform encephalopathy was ruled out based on negative testing.¹⁹

Musculoskeletal Disorders

Disseminated Idiopathic Myofasciitis

Disseminated idiopathic myositis (DIM), or myofasciitis, is a recently described inflammatory disease of muscle and fascia that usually occurs in young ferrets ranging from 5 to 24 months of age. Clinical signs include acute to subacute onset of lethargy, pyrexia, recumbency, ataxia, posterior paresis, pain associated with movement or touch, anorexia, bruxism, and/or difficulty swallowing or drinking.18., 40. Ferrets with this disease are most often recumbent and in extreme pain; they may vocalize or attempt to bite when touched or examined. They are usually febrile, with temperatures ranging from 104° to 108°F .

Hematologic abnormalities associated with myofasciitis can be dramatic. The most remarkable is a mature neutrophilic leukocytosis, ranging from mild to severe, with reported total white blood cell (WBC) counts ranging from 8900 to 79,500 or higher. One author (NA) has seen WBC counts over 100,000 with this disease. The WBC count may also be normal at initial presentation but may then increase dramatically during the course of the disease. Mild to moderate anemia is also commonly present and is usually nonregenerative. Biochemical abnormalities reported with this disease are mild to moderate increases in concentrations of alanine aminotransferase (ALT) and glucose and mild hypoalbuminemia. Interestingly, increases in aspartate aminotransferase (AST) and creatine kinase (CK) concentrations are not associated with this disease.18., 40.

Gross pathologic changes at necropsy may be absent or may include esophageal dilation, red and white mottling of the esophagus, and white streaks in the heart, diaphragm, and intracostal muscles. Atrophy of the limb musculature and also the tongue and diaphragm is reported.18., 40. Histopathologic lesions are moderate to severe areas of suppurative pyogranulomatous inflammation, most commonly in the skeletal muscle, esophagus, and heart but also identified in smooth muscle tunics and the submucosa of the stomach, small intestine, and urinary bladder. This profound inflammation occurs in the absence of any infectious or inciting agent. Inflammation is most commonly seen in the muscular tunics but also involves the submucosal and serosal tunics in some cases and frequently extends into the surrounding fascia and adipose tissue. Within inflamed foci, some small arteries, veins, and capillaries also have endothelial cell hypertrophy, neutrophil margination, and perivascular edema or fibrin deposition.¹⁸

Suspect myofasciitis in a recumbent ferret with unresponsive or cyclic pyrexia, muscle pain or sensitivity to touch, neutrophilic leukocytosis, and anorexia. Confirm the diagnosis antemortem with skeletal muscle biopsy from a hind limb. For necropsy diagnosis, be sure to include esophageal samples among those to be examined histologically. Treatment is often unrewarding, although some authors have reported success with aggressive supportive care along with the use of immunosuppressive doses of prednisolone (1 mg/kg PO q12h for 3 months or longer) and cyclophosphamide (10 mg/kg on days 1 and 14, then every 4 weeks for 3 months or longer) along with chloramphenicol (50 mg/kg PO q12h for 6-8 weeks). Aggressive supportive care can be prolonged (several weeks) and must include fluid therapy and nutritional supplementation; it should also include GI protectants and fever control.⁴⁰ The author (NA) has treated some ferrets successfully with this protocol.

The cause of this disease is unidentified to date. Investigations into bacterial, fungal, viral, environmental, husbandry, and vaccination status have failed to identify an agent. Results of PCR assays for Neospora caninum and Toxoplasma gondii have been negative, as have immunohistochemical stains for these organisms along with Sarcocystic neurona and feline and ferret coronavirus antigen.¹⁸

Myasthenia Gravis

Acquired autoimmune myasthenia gravis was reported in a 7-month-old ferret. The clinical presentation included episodic hind limb weakness, flaccid paraparesis that progressed to tetraparesis, and mild megaesophagus. Diagnosis was made by nerve conduction velocity, which was diminished in the hind limbs; positive serologic testing for antiacetylcholine receptor antibodies; and response to neostigmine methylsulfate. Response to edrophonium hydrochloride can also be used in diagnostic testing. Treatment with pyridostigmine bromine (1 mg/kg PO q12h) initially produced a return to normal, but clinical signs progressed within 1 month, leading to euthanasia.⁶ Prednisolone at immunosuppressive doses is commonly used concurrently with pyridostigmine bromine in the treatment of myasthenia gravis and should be considered in the treatment of this disease. The authors have also diagnosed and treated this disease in a ferret.

Miscellaneous Diseases

Systemic mycoses, which may contribute to CNS depression and lethargy, have been reported in ferrets.9., 12. Cryptococcus species have been identified as a cause of meningitis in ferrets, including one that died from congestive heart failure after being treated with steroids for intervertebral disk disease.¹² Blastomycosis has also been identified in ferrets, with multifocal granulomatous meningoencephalitis described in one ferret with systemic blastomycosis.12., 28. One author (NA) has diagnosed a case of disseminated histoplasmosis in a ferret with fungal organisms present in the brain at necropsy. Diagnosis of these diseases is based on clinical signs, radiographic changes, and isolation of the causative organism. Impression smears of draining tracts or CSF analysis may be useful in identifying the organism.

Other Metabolic Diseases

Toxemia of pregnancy is most common in young, primiparous jills late in gestation. Although hypocalcemia, hypophosphatemia, and ketosis may develop, neurologic signs are rare unless hepatic lipidosis is so severe that encephalopathy is present.³

One case of suspected pseudohypoparathyroidism was reported in a ferret that presented for seizures and had low serum calcium, high serum phosphorus, and high serum parathyroid hormone concentrations. This patient responded to lifelong treatment with vitamin D (dihydrotachysterol) and supplemental calcium.⁵³

Paresis or paralysis of the hind limbs has also been described in ferrets with heartworm disease.²

An eosinophilic granulomatous infiltrate in the choroid plexus was reported in a ferret with diffuse eosinophilic gastroenteritis and multisystem involvement.¹⁵ Toxoplasmosis has been identified in ferrets; most likely disease develops after exposure to cat feces or raw meat.4., 5., 13. Copper toxicosis has been reported and was believed to be congenital in two ferrets with CNS depression. Diagnosis was based on histopathologic changes in the liver as well as copper levels.¹⁷ Iniencephaly in a litter of ferrets has also been described.⁵² Other congenital anomalies of the brain and spinal column probably occur but have not been reported.

Additional diseases of the brain and spinal cord, as well as muscular and metabolic disorders that can cause clinical signs as described in this chapter, are likely to be identified as our diagnostic capability improves with newer technology.