Episodic increases in liver transaminases, with or without overt clinical signs, have been identified in bottlenose dolphins (Tursiops truncatus).2 Associated changes in hematological and serum biochemical changes can provide important clues as to what may cause this condition. A retrospective case-control study involving six cases and 12 age- and sex-matched controls was conducted in a managed dolphin population to compare hematological and serum biochemical values over time. Compared to the control animals, cases were significantly more likely to have higher serum globulins, bilirubin, GGT, iron, glucose, triglycerides, and cholesterol levels, greater erythrocyte sedimentation rates, and lower platelet counts. In a separate study, phlebotomy treatment of two of these cases for iron overload led to a significant decrease in serum iron, AST, ALT, serum globulins, and erythrocyte sedimentation rate.1 Similar case-control findings reported in humans with chronic hepatitis have been associated with iron overload, predisposing metabolic risk factors including diabetes, and overlap syndromes involving immune responses that may or may not be associated with viral infection. Follow-on investigations targeting multiple etiologies, specifically metabolic risk factors, autoimmune responses, and viral infections are needed to identify key preventive measures and treatment protocols for dolphins with iron overload and chronic liver disease.
The authors wish to thank the management team and animal care staff at the U.S. Navy Marine Mammal Program.
1. Johnson S., S. Venn-Watson. S. Cassle, C.R. Smith, E. Jensen, and S.H. Ridgway. 2009. Phlebotomy therapy for iron overload in Atlantic bottlenose dolphins (Tursiops truncatus). J Am Vet Med Assoc, in press.
2. Venn-Watson S., C.R. Smith, and E.D. Jensen. 2008. Assessment of increased serum aminotransferases in a managed Atlantic bottlenose dolphin (Tursiops truncatus) population. J Wildl Dis 44: 318-330.