Abstract
An approximately 31 year-old, 126 kg, adult female Pacific white-sided dolphin (Lagenorhynchus obliquidens) maintained in a semi-closed, 3.8 million litre captive display pool, with a long history of intermittent gastrointestinal problems was presented with sudden anorexia, abdominal pain, and vomiting. The aging dolphin had had multiple antibiotic treatments in response to inflammatory blood profiles and inappetence at several public display institutions and was known as an "old dolphin that often goes off". Although gastrointestinal disease had been suspected, the cause of the recurrent inflammatory changes in the peripheral blood was never definitively diagnosed. Starting in 2006, budding yeast and pseudohyphae were found on oral and gastric cytology in association with lethargy, inappetence and recurring inflammatory changes. Antifungal agents including oral itraconazole and nystatin were used and appeared to speed recovery and decrease the severity of the clinical signs. Repeated endoscopy of the esophagus and proximal stomach showed no significant lesions although a thick koilin coating of the stomach occasionally hampered close examination of the gastric mucosa.
In March 2009, the dolphin was being treated for recurrent gastritis suspected to be in association with yeast that was assumed to be Candida albicans based on cytological morphology. Treatment included nystatin and itraconazole and several antibiotics due to the unusually long course of her illness and poor response to therapy. She appeared to recover well and within 4 weeks was eating her normal diet and performing high energy behaviours. In May 2009, she was found anorexic and weak. Endoscopy of the proximal digestive tract and sonography of the thorax and abdomen revealed no significant lesions. However, over the next 3 days the animal declined very quickly. Abdominal radiographs revealed an unusual gas-filled loop of bowel in the craniodorsal abdomen and the dolphin showed repeated vomiting and severe abdominal pain. Oral fluids remained in the first chamber of the stomach for prolonged periods of time. Serum biochemistry results indicated hepatic disease and renal failure. The dolphin showed poor response to intravenous fluid therapy and continued to decline. Repeated abdominal ultrasonography revealed frank abdominal fluid and a decision to euthanize was made based on the probability of a perforated gastrointestinal tract and peritonitis. The dolphin died prior to injection of the euthanasia solution.
Necropsy showed an emaciated animal with moderate abdominal distension. On incision of the abdominal wall, there was approximately 2 L of serosanguinous ascites and an intestinal torsion within the craniodorsal aspect of the abdominal cavity with displacement of adjoining viscera. Microscopically, there was a marked fibrinosuppurative enteritis with florid intralesional yeast. Special culture on selective media identified Candida krusei. In comparison to C. albicans, this yeast has an unusual sensitivity pattern to azoles.
Intestinal torsion has been reported in a wide variety of domestic and free-ranging species including several cetacean species and has been associated with chronic inflammation caused by neoplasia, parasites and other pathogens that are thought to increase gastrointestinal spasticity. It has also been theorized to be associated with various high energy behaviours in dolphins maintained in public display aquaria. This case highlights the role of yeast in gastrointestinal disease of cetaceans, the limitations of examination of the proximal digestive tract in diagnosing gastrointestinal disease, the importance of speciation of a pathogen to initiate appropriate therapy and the possible association between chronic inflammatory disease and intestinal torsion in a cetacean.
Acknowledgements
The authors would like to thank Brian Sheehan, Sherri Reficio, Adria Young, Leonora Marquez, Lisa Lam and the absolutely incredible marine mammal husbandry team, as well as our amazing veterinary technicians--Chelsea DeColle and Gwyneth Nordstrom--at the Vancouver Aquarium. Drs. Chris Dold, Jim McBain, Todd Schmitt and Tom Reidarsen from SeaWorld, Dr. Bill Van Bonn from The Marine Mammal Center and Dr. Eric Jensen from the US Navy's Marine Mammal Program provided invaluable advise during this case.