Clinical, surgical, and pathological findings in client-owned rabbits with histologically confirmed appendicitis: 19 cases (2015-2019).

OBJECTIVE: To report clinical, surgical, and pathological findings in client-owned rabbits with histologically confirmed appendicitis. ANIMALS: 19 rabbits. PROCEDURES: Medical records for client-owned rabbits that had a histologic diagnosis of appendicitis were reviewed. RESULTS: Median age of the rabbits at presentation was 24.0 months (range, 4 to 84 months). Seventeen cases occurred during the summer and fall seasons. Decreased appetite (17/19 rabbits), abnormal rectal temperature (hyperthermia, 9/16 rabbits; hypothermia, 4/16 rabbits), hypocalcemia (8/11 rabbits), and hypoglycemia (7/15 rabbits) were common signs. Abdominal ultrasonography and CT findings were suggestive of appendicitis in 6 of 8 rabbits and in 1 of 2 rabbits, respectively. Of the 6 rabbits that received medical treatment, 3 died at 48 hours, 1 died at 24 hours after hospitalization, and 1 died at 10 days after presentation; 1 rabbit was alive at 1,030 days after presentation. Of the 8 rabbits that underwent appendectomy, 3 died before discharge from the hospital and 1 died 113 days after surgery; 4 rabbits were alive at 315, 334, 1,433, and 1,473 days after presentation. The remaining 5 rabbits either died or were euthanized before treatment could be instituted. In each of the 19 rabbits, the appendix had evidence of severe inflammation with mucosal ulceration, heterophilic inflammation, and necrotic debris. CLINICAL RELEVANCE: For rabbits with decreased appetite and an apparently painful abdomen, hyperthermia, hypocalcemia, or hypoglycemia, appendicitis should be considered as a differential diagnosis. Further comparisons of medical and surgical treatments are required to establish treatment recommendations for rabbits with appendicitis.

Ultrasound and computed tomography of sacculitis and appendicitis in a rabbit.

A 9-month-old neutered male rabbit was referred for lethargy, anorexia, and gastrointestinal stasis. Routine hematology, serum biochemistry, and diagnostic imaging were performed. Computed tomography revealed a wall thickening of the sacculus rotundus and appendix, which was further confirmed on abdominal ultrasound. Full thickness biopsies were collected with histopathology diagnosing a chronic multifocal heterophilic granulomatous sacculitis and appendicitis. The patient was treated medically and at 6 weeks follow-up, clinical signs and intestinal changes had completely regressed. Inflammation of the sacculus rotundus and appendix should be considered as a cause of gastrointestinal stasis in rabbits.

Acute appendicitis in a chimpanzee (Pan troglodytes).

BACKGROUND: A 7-year old, female chimpanzee (Pan troglodytes) developed acute abdominal pain and anorexia. An irregular, mineral opacity was identified in the caudal right quadrant of the abdomen on radiographs and computed tomography scan, which appeared to be in the region of the cecal appendage. RESULTS AND CONCLUSIONS: A diagnosis of acute appendicitis was made based on clinical signs, abnormal haematology findings, and consultation with a human radiologist. Exploratory laparotomy was performed and the cecal appendage was removed. On histologic examination, the mucosal epithelium contained eosinophilic and neutrophilic inflammation. The inflammation extended through the tunica muscularis to the serosal surface and adjacent mesentery. The histologic findings were consistent with acute appendicitis in humans. The chimpanzee recovered well from surgery with immediate improvement in clinical signs and no post-operative complications.

[Occurrence of granulomatous appendicitis in rabbits].

Granulomatous appendicitis was observed in all of the 45 Japanese white rabbits examined. Histologically, multiple microgranulomas were accompanied with foreign body giant cells and focal calcifications in lymph nodules of appendix. Foreign body giant cells contained hair coat and larvae of Passalurus ambiguus. In addition, the sacculus rotundus and mesenteric lymph nodes were affected with the same lesions. PAS- and Gram- positive bacilli were phagocytized in the microgranulomas and macrophages. They were also stained positively with the immunoperoxidase method for the auto-sera of rabbits. Isolation of these bacilli in pure culture has not yet been accomplished. The occurrence of granulomatous lesions due to tuberculosis, pseudotuberculosis, tularemia and actinomycosis seems unlikely in the present cases because none of these organisms nor characteristic lesions were detected. It was suggested that the Gram-positive bacilli appeared to play a role in granulomatous appendicitis.