Severe hepatic fibrosis and bile duct hyperplasia in four Amazon parrots

Severe bile duct hyperplasia with bridging hepatic fibrosis was identified in four Amazon parrots (Amazona spp.) with hepatomegaly. Clinical signs included regurgitation, dyspnea, yellow urates, and abdominal distention. Three birds in which clinical pathologic data were obtained had high aspartate transaminase activity, hypercholesterolemia, and high bile acid concentrations. Histologic features included diffuse hyperplasia of bile ducts, bridging fibrosis, and mild heterophilic hepatitis. The two birds diagnosed clinically responded to palliative treatment including amoxicillin, lactulose, and dietary changes with gradual improvement in behavior and clinical laboratory values. The underlying cause of this syndrome remains unclear; exposure to hepatotoxins is probable, although an undetected infectious agent is possible. The notable severity of bile duct hyperplasia and hepatic fibrosis in Amazon parrots may indicate a unique sensitivity of this genus to hepatotoxins or hepatic injury. Severe bile duct hyperplasia may precede bile duct neoplasia in Amazon parrots.