Immune-mediated hemolytic anemia in a bottlenose dolphin: case report and literature review

A 15-y-old captive-born female bottlenose dolphin (Tursiops truncatus) had slowly progressive lethargy, inappetence, and pallor of the oral mucosa. Serial hemograms and serum biochemistry analysis revealed hemolyzed plasma, gradually severe anemia with reticulocytosis, spherocytosis, pronounced neutrophilia with left shift and toxic change, and indirect hyperbilirubinemia. Urinalysis identified both hemoglobinuria and bilirubinuria. Hyperglobulinemia with polyclonal gammopathy was evident by protein electrophoresis, and the saline agglutination test was positive. Splenomegaly and hyperechogenic liver were also observed on ultrasound. These findings meet the diagnostic criteria established for immune-mediated hemolytic anemia (IMHA) in small animals, which is extremely rare in cetacean species, and, to our knowledge, has not been fully documented. Several potential triggers of a secondary IMHA were ruled out, including the most common cetacean virus, exposure to new drugs, and recent vaccination events. Following recommendations from companion animal medicine, immunosuppressive therapy was implemented and proved effective in this bottlenose dolphin; the CBC returned to normal after 3 mo of treatment.