Summary

A sixteen year old female Atlantic bottlenose dolphin was euthanized following an eight week struggle to diagnose and treat a severe hepatopathy. She had been wild-caught at approximately 3 years of age in the Gulf of Mexico and had resided at the Aquarium of Niagara since capture. She had been generally healthy during that time. Approximately eight months previously, this animal had shown signs of decreased appetite and elevated serum transaminases, but had eventually responded to oral tetracycline. Routine complete blood counts, serum chemistry profiles, and erythrocyte sedimentation rates were normal in the interim period.

Clinical signs began with lethargy and decreased appetite, which progressed to total anorexia, intermittent vomiting, and cachexia. Routine blood profiling revealed progressive marked elevations of serum transaminases ALT, AST, and LDH indicating acute severe hepatocellular damage. Associated hematologic parameters revealed elevated erythrocyte sedimentation rate and fibrinogen, lymphopenia, and mild anemia. Total white blood cell counts were never elevated. Prothrombin time gradually increased until bleeding was noted clinically from mild abrasions. Vitamin K₁ supplementation reversed this trend.

The following diagnostic tests were performed (with results):

 Serum Bile Acids: (87.0)

 Serum protein electrophoresis: (no monoclonal bands noted)

 LDH isoenzymes: (increased LD 4 - consistent with liver isoenzyme)

 Serum Iron profile: (One week into disease: Fe 1197 ug/dl, TIBC 1318 ug/dl, %sat 91)

 (Five weeks into disease: Fe 1500 ug/dl, TIBC 1681 ug/dl, %sat 89)

 Plasma Zinc: (1483 ug/L; Human ref range (550 - 1400))

 Blood Lead: (< 2 ug/dl)

 Serum ceruloplasmin - indicator of Copper storage disease in humans: (<2 mg/dl)

 Blood Copper: (normal)

 Abdominal radiography: (non-diagnostic with field equipment used)

 Abdominal ultrasonography: (no focal liver lesions, borders fairly sharp, parenchymal echogenicity uniform)

 Upper gastric endoscopy: (no evidence of ulceration or foreign material)

 Human Hepadenavirus screen for hepatitis A, B, and C: (negative)

 Serum neutralization titer to Canine Distemper virus: (neg at 1:4)

 Morbillivirus titer: (neg)

 Fungal serology: (Blastomyces, Coccidioides, Histoplasma, Aspergillus, Candida, Cryptococcus all negative)

 Trypsin-like Immunoreactivity: (2.51 ng/ml) Canine reference 5 - 25 ng/ml

Attempts to maintain hydration and decrease catabolic rate by forced feeding or stomach tubing two to four times daily for five weeks with a mixture of fish gruel, water, electrolyte solution, and a commercial enteral protein/carbohydrate product (TwoCal) only helped slow the progression of emaciation.

Medications used during part or all of treatment included antibiotics (tetracycline, cephalexin, amikacin), antifungals (itraconazole, nystatin), gastrointestinal support (cimetidine, carafate, pink bismuth, DiGel simethicone, metoclopramide), appetite stimulants (megesterol acetate, prednisolone, diazepam), and multiple vitamins and mineral supplements (including folic acid, ferrous gluconate, and Vit K1).

Despite intensive efforts to support the animal and correct the liver disease, the anorexia never resolved and weight loss became extreme (114 lbs over 8 wks, approx 30% of normal body wt). Depression and malaise became critical when the dolphin could no longer swim to the surface to breathe. Humane euthanasia was elected when final blood work suggested impending septicemia. Final blood cultures revealed many and pure Shewanella putrefaciens.

Post mortem examination failed to identify an etiologic agent but revealed vacuolar, diffuse, moderate hepatopathy, moderate biliary hyperplasia, and moderate extramedullary hematopoiesis. Lymphoid depletion; chronic, non-ulcerative, multifocal gastroenteritis; chronic, multifocal interstitial pneumonia; and mild to moderate generalized inflammation were also reported. Virus isolation attempts from frozen tissue samples were unrewarding. Bacterial culture from liver tissue revealed Shewanella efaciens and Vibrio fluviafis.