Abstract

An eighteen year-old, estimated 200 kg, female Atlantic bottlenose dolphin (Tursiops truncatus) was partially anorectic and in fair body condition, one day after parturition of a healthy calf. During the next six months the damn's condition declined, despite intensive efforts to reverse the trend. The dolphin terminally rapidly declined to a moribund state and euthanasia was elected. Postmortem examination revealed numerous mesenteric rents and abdominal fibrous adhesions with herniation and volvulus of a 2 m portion of jejunum through the largest mesenteric rent. The entrapped portion of jejunum exhibited massive, acute, necrosis and thrombosis of associated vasculature. Histologically, the fibrous adhesions were also associated with significant granulomatous inflammation indicative of past bouts of peritonitis.

Prior to previous births, the animal exhibited prolonged anorexia, up to 2-months duration, and hematological evidence of renal disease. The renal disease was evidenced by elevated blood urea nitrogen (BUN) and creatinine while an inflammatory process was indicated by an increase in the erythrocyte sedimentation rate (ESR). Ultrasonically there was increased echogenic material within the kidneys consistent with renal calculi.

By the second day after the last parturition, the animal was lethargic and had a diminished appetite. The animal was given a single dose of dexamethasone and placed on amoxicillin. Less than one hour after the single dexamethasone dose, she began eating. During the next 20 days, trainers reported extreme post-prandial discomfort, which was evidenced by swimming away from the trainer, breaching, ventroflexion, squinting of the eyes, and avoidance of the remaining feed. The hyperactive behavior lasted less than one minute after which she would float listlessly for several hours and exhibit slow ventroflexion of the fluke. During this period she was receiving a low dose of prednisone, amoxicillin, and itraconazole. She would immediately stop eating if not maintained on a low dose of steroids. Although food consumption had increased from 5 kg to 10 kg per day, the animal lost an estimated 15 kg. Over the next two months, the dolphin had an inconsistent appetite and continued to lose weight. Day 150 post-parturition abnormalities first appeared in her hemogram and serum analysis. T here was a neutrophilia with a left shift, an increased ESR BUN, creatinine, and total protein. The antibiotics were changed to ciprofloxacin and the low-dose steroids and itraconazole were continued. Fluid therapy of 2 L oral water per day was initiated. Feeding now consisted of a minimum of 5 kg of fish per day, whether voluntarily or by force feeding. The dolphin continued to slowly deteriorate, until the last 24 hours when there was a sudden and dramatic decline in condition. The dolphin ultimately became moribund and euthanasia was elected; the animal was anesthetized with 800 mg of zylazine by intramuscular injection, and then euthanatized with the administration of 80 ml of T-61 intravenously.

At necropsy, she weighed 130 kg and was 2.43 meters long. The animal was poorly muscled and had minimal to no adipose stores. The integument had numerous abrasions and lacerations with histologically evident, chronic-active dermatitis with superficial bacteria and amoebae. There was approximately two liters of putrid, green-brown abdominal fluid. The mesentery of the small and large bowel had numerous rents, usually 2-3 cm to 4-5 cm diameter, but with one approximately 10-12 cm diameter in the mesentery of the distal third of the jejunum. All the defects had smooth borders which often were slightly thickened. An approximately 2 meter length of the distal jejunum was herniated through the largest mesenteric rent and has twisted clockwise 720° on its mesenteric axis, as viewed from the ventral aspect. A 0.5 meter portion of this twisted jej unum was transmurally dark red, markedly thickened, turgid, and friable. Histologically, this area exhibited transmural, acute necrosis and suppuration. The vasculature associated with this necrotic portion of bowel was extremely prominent, tortuous, and engorged, and histologically contained large arterial and venous, fibrinous to occasionally suppurative thrombi. Herniation of short to moderately long regions of jej unum and colon through numerous other mesenteric rents was also noted, but these segments of bowel were grossly normal and easily reduced. Abundant fibrous adhesions between loops of both small and large bowel and viscera were also present. Histologically, these fibrous adhesions had moderate granulomatous infiltrates suggesting past bouts of peritonitis. Additionally, the liver had extensive capsular fibrosis with parenchymal loss and moderate granulomatous hepatitis. The pancreas also had extensive fibrosis, moderate granulomatous inflammation and regenerative, nodular hyperplasia. The kidney had moderate, multifocal, medullary calcification, with calices often containing small uroliths with some up to 1.5 cm in diameter; there was adequate renal tissue remaining to maintain organ function. One primary and two secondary bronchi had occlusive, acute, blood clots, and moderate, peracute, myo cellular necrosis was present histopathologically; these lesions were likely from terminal shock and toxemia. The heart and large vessels, and the nervous and hemic-lymphatic systems were normal.

The rapid decline in the last 24 hours was due to the volvulus and resultant bowel necrosis; the lesions would soon have resulted in death from either toxemia and/or sepsis. The volvulus and jejunal necrosis occurred because of the numerous rents in the mesentery. The rents, multitude of fibrous adhesions with granulomatous infiltrates, and chronic hepatic and pancreatic lesions strongly suggest past, recurrent bouts of severe peritonitis. The numerous historical episodes of disease and abnormal breaching and arching behaviors were likely due to peritonitis and/or herniations of bowel through rents with partial compromise and spontaneous reduction and recovery. Surgical correction of the lesions would have been futile considering the large number of rents and fibrous adhesions.