An apparently healthy female crossbred Labrador retriever-poodle dog with severe intra-abdominal adhesions as an incidental finding to ovariohysterectomy

Abstract

An apparently healthy 1-year-old, female crossbred Labrador retriever-poodle dog was brought to a veterinary clinic for elective ovariohysterectomy (OVH). Severe abdominal adhesions complicated the procedure. There was no report of a previous illness or surgical procedure that would be a predisposing cause for the adhesions. The OVH was completed despite the adhesions and the dog recovered well. It is unclear whether this was simply a case of severe intra-abdominal adhesions or an atypical sclerosing encapsulating peritonitis (SEP). The differential diagnoses include inflammatory processes, a genetic predisposition, or an idiopathic cause. Fourteen days later, at the time of surgical staple removal, the dog was healthy and had reportedly been doing very well. Although rare, intra-abdominal adhesions can occur in young and previously healthy dogs without causing clinical signs. Veterinarians should be aware of such a condition when approaching abdominal surgeries and be prepared to manage these cases appropriately.

A 1-year-old, female intact crossbred Labrador retrieverpoodle dog weighing 18.4 kg (body condition score: 4/9) was brought to a mixed general practice veterinary hospital in Sundridge, Ontario for elective ovariohysterectomy (OVH). The dog was apparently healthy based on information obtained from the owners and based on a physical examination and laboratory findings on the day of the surgical procedure.

Previous medical history included an unknown dose of selamectin (Revolution; Zoetis, Kirkland, Quebec) administered topically at 6 wk of age by the breeder. Since being obtained by the current owners at 8 wk of age, they have had no concerns of illness at any time. The appropriately sized tablet of afoxolaner and milbemycin oxime (Nexguard Spectra; Boehringer Ingelheim, Burlington, Ontario), based on the dog’s weight at the time, was administered orally at 8.5 wk of age and again at 15 wk of age. The dog had experienced 1 heat cycle 5 mo before the surgical procedure, at 7 mo of age. Rabies, leptospirosis, distemper, adenovirus, parainfluenza, and parvovirus vaccinations were all up-to-date.

A physical examination on the morning before to surgery revealed no abnormal findings. All vital parameters were within normal limits. A blood sample was collected for a complete blood (cell) count (CBC), prothrombin and partial thromboplastin times, and the results of these tests were within normal limits.

The following drugs were given as pre-medication: hydromorphone (Hydromorphone; Sandoz, Boucherville, Quebec), 0.1 mg/kg BW, IM, dexmedetomidine (Dexdomitor; Zoetis, Kirkland, Quebec), 0.0015 mg/kg BW, IM, midazolam (Midazolam; Sandoz, Boucherville, Quebec), 0.1 mg/kg BW, IM. An intravenous catheter was placed, and the dog was induced with propofol (Propofol; Baxter, Mississauga, Ontario), 2 mg/kg BW, IV. One milliter of lidocaine 2% with epinephrine (Lidocaine Hydrochloride and Epinephrine Injection USP; Pfizer, Kirkland, Quebec) was diluted with 1 mL of NaCl and injected subcutaneously along the planned incision site. Pre-operative cefazolin (Cefazolin; Sandoz, Boucherville, Quebec), 22 mg/kg BW, IV was given. Perioperative meloxicam (Metacam; Boehringer Ingelheim, Burlington, Ontario), 0.2 mg/kg BW, SQ and maropitant (Cerenia; Zoetis, Kirkland, Quebec), 1 mg/kg BW, SQ were given. The dog was maintained under anesthesia using isoflourane inhalant and oxygen on an F-circuit system (fresh gas flow rate of 100 mL/kg/min).

A ventral midline celiotomy approach was used. Of note, there was more bleeding from the skin than expected. Attempts at locating the left uterine horn with a spay hook were unsuccessful. The abdominal incision was extended cranially and caudally to improve visualization. The uterine body was located dorsal to the bladder and the uterine horns were subsequently identified revealing that the uterine horns were adhered to a section of small intestine. Additional adhesions were encountered upon attempted exteriorization of the uterus. It became apparent that a clear-to-pink, thin, fibrous membrane was encapsulating the abdominal organs and affixing them to each other and to regions of the body wall by their parietal surfaces. There were adhesions between small intestine, colon, bladder, uterine horns, and body wall. The uterine horns were gently freed from the small intestine and the OVH was completed as usual. While attempting to free the right ovary and uterine horn from the adhesions binding it to the small intestine, the ovarian vascular pedicle tore. It was promptly recovered and ligated. No other adhesions were debrided, and no biopsies were taken. A routine 3-layer abdominal closure was employed with surgical staples used for skin closure. Anesthesia was routine and the dog recovered from surgery uneventfully. Laser therapy was performed over the incision immediately postoperatively on an anti-inflammatory setting; a routine practice at this clinic. The dog was discharged with 3 days’ worth of meloxicam administered at 0.1 mg/kg BW, PO.

Post-recovery and on gross evaluation of the reproductive tract, both ovaries were smaller than expected (1 cm × 1.5 cm) and the ovarian tissue was dark purple in color when incised for further inspection. Both uterine horns and ovaries were submitted to the Animal Health Laboratory, University of Guelph for gross and histopathological evaluation.

The dog was monitored in hospital for 6 h after surgery before being discharged to the care of the owners, who reported that the dog had continued to recover without complication when contacted 2 d later. The dog returned 14 d after the procedure for staple removal. The incision had healed well, and no abnormalities were identified on physical examination.

The diagnostic pathology report from the Animal Health Laboratory reported minimal peri-uterine serosal inflammation on histopathologic evaluation of the uterus and ovaries. It was concluded that the abdominal adhesions were not related to a pathology of the reproductive system, such as a previous pyometra or metritis.

Discussion

Intra-abdominal adhesions are bands of fibrous tissue that form between the peritoneal surfaces of abdominal organs and/or body wall (1). Adhesions are highly cellular, vascular, and dynamic structures that are influenced by complex signaling mechanisms (2). Although the complete pathophysiology is not entirely understood, adhesions are known to be the result of abnormal peritoneal healing in which various cell types signal fibroblasts to secrete large amounts of extracellular matrix (1). This abnormal healing establishes fibrin bridges between organs. In normal circumstances, local fibrinolysis would prevent fibrin deposition from becoming a fibrous adhesion. However, if local fibrinolysis is insufficient, the fibrin bridges remain and are infiltrated with fibroblasts and capillaries, creating a fibrous adhesion (1).

Intra-abdominal adhesions have been most frequently reported to occur in humans and horses. In humans, they most commonly occur following abdominal surgery and long-term peritoneal dialysis (3,4). In horses, intra-abdominal adhesions occur most often after abdominal surgery and are associated with peritonitis (2). Intra-abdominal adhesions are less frequently reported in dogs, as supported by the small body of available literature and when compared to the number of human and equine studies available. Although the exact mechanisms that predispose adhesion formation remain unclear, general groups of causes include surgical trauma, inflammation of any sort, hemorrhage, thermal or chemical injury, ischemia, genetic predisposition, and reactions to foreign bodies (1,4).

Sclerosing encapsulating peritonitis (SEP), also known as encapsulating peritoneal sclerosis, describes a disease process in which severe intra-abdominal adhesions bind multiple abdominal organs together (5). This rare disease is a known sequela of chronic peritonitis (5). Simple abdominal adhesions can be debrided; however, SEP is characterized by fibrous connective tissue that essentially replaces the visceral peritoneum and is effectively impossible to separate from the underlying organs (5). When severe, SEP has been reported to cause ileus and intestinal obstruction in humans (6). Although this disease process is mainly reported in human patients, a handful of veterinary cases are reported: 11dogs (ranging in age from 5 mo to 13 y) and 2 cats (10 mo and 5 y) (7). Half of the canine cases were idiopathic, the other half were secondary due to bacterial peritonitis (6), foreign body ingestion (6), history of a uterine rupture (8), leishmaniasis (9) or hepatocellular carcinoma (10). One cat was diagnosed with pansteatitis and the other had undergone ovariectomy 7 mo previous (6,7). In humans, SEP has been referred to colloquially as abdominal “cocooning,” which describes how the adhesions cause abdominal organs to become bound together. In dogs, cats, and humans, clinical signs of SEP include nausea, vomiting, abdominal pain, palpable abdominal mass, and ascites (6).

Upon review of the available literature, relatively few case reports describing SEP in dogs and cats exist. Most describe dogs that present with clinical signs of gastrointestinal illness and a known inciting cause of peritonitis (5–11). A case report outlining an incidental OVH finding of abdominal adhesions in a dachshund was the report closest in similarity to the case outlined herein (8). The report determined via histopathology results, that the dachshund had previously suffered from pregnancy complications. Due to coming from a shelter, her history was unknown for the previous 8 y (8). In contrast, the dog in this report has a complete history, aside from the first 8 wk of life spent with the breeder and was a healthy dog without any known predisposing causes for abdominal adhesions.

It remains unclear if the dog discussed in this report was suffering from early stages of SEP, an atypical SEP, or from severe abdominal adhesions. Grossly, SEP is reported as being a thick white to pink friable membrane that cannot be separated from underlying organs (6). The membranes encountered in this dog’s case were thin and clear-to-pink, and could be separated from the affected organs, though with difficulty. Previous reports allude to SEP adhesions as being vascular, whereas the adhesions in this dog did not bleed as they were broken down (9). The abdominal contents in this case were “cocooned” together, as is seen in cases of SEP. Sclerosing encapsulating peritonitis is not diagnosed histologically; however, acquiring samples of the adhesions for histopathology may have provided supporting evidence for a definitive diagnosis (6).

The differential diagnoses that may explain the formation of abdominal adhesions in this dog were considered. A previous abdominal surgical procedure is a known risk factor for the development of abdominal adhesions (1) but was ruled out in this case by taking a thorough history from the dog’s owners. Uterine rupture, related to a pyometra or ectopic pregnancy, and severe metritis were ruled out by the histopathology report. Although it is unlikely her owners would have overlooked associated clinical signs, the dog may have suffered from an inflammatory process within her abdominal cavity, such as an intestinal accident, hematogenous bacterial infection, pancreatitis, transmural cystitis, penetrating wound, migrating foreign body, or intestinal foreign body. Based on the above, it seems most likely that the cause of the dog’s intra-abdominal adhesions occurred while it was still with the breeder. All incidents described remain possible, plus the possibility of an ascending umbilical infection. In addition, as her intestinal parasite prevention protocol is unknown during this time, visceral larval migrans following intestinal parasite infestation related to poor parasite prevention protocol is possible. Idiopathic or genetic causes cannot be ruled out.

When abdominal adhesions are encountered during a routine veterinary surgery, adhesiolysis further than what is required to complete the procedure is not recommended unless the adhesions are causing clinical problems for the dog (9). Surgical trauma is known to stimulate additional adhesion formation (1). If associated peritonitis is suspected, the abdomen should be lavaged before closure (6). If adhesiolysis is warranted, caution should be taken. Simple adhesions can be debrided, but the adhesions encountered in a case of SEP present a challenge as they have essentially replaced the peritoneum (9).

Many different drugs have been used in humans and horses to try and prevent adhesion formation and to break down existing adhesions, with various success. Glucocorticoids have been used to stop the inflammatory response, thus preventing fibrin deposition and collagen synthesis and maturation (3). Tamoxifen is a selective estrogen receptor modulator that is commonly used to treat fibrosclerotic disorders by inhibiting fibroblastic production (11). Tamoxifen was successfully used to treat SEP in one dog (11). Heparin, an anticoagulant, has also been used in humans to prevent fibrin clot formation and thus inhibit adhesion formation, though a consensus on its effectiveness has not been reached (2).

The dog discussed in this case report may be predisposed to intestinal accidents related to foreign body ingestion, or other ailments that would be worsened due to limited mobility of the organs within the abdomen. With the young age of this dog and the extent of the lesions, there is also cause for concern of adhesion progression becoming akin to abdominal cocoon syndrome in which the adhesions act to sclerose the viscera together, impeding their function. Any future abdominal surgical procedures may be complicated by the presence of intra-abdominal adhesions.

Although rare, intra-abdominal adhesions can occur in young and previously healthy dogs without causing any clinical signs of illness. General practitioners should be aware of such when approaching abdominal surgeries on a regular basis and be prepared to manage these cases appropriately.