Hepatic encephalopathy in captive scimitar-horned Oryxs (Oryx dammah)

Three cases of hepatic encephalopathy were diagnosed in scimitar-horned oryxs housed at a zoo. Administration of amino acid and ornithine-aspartate fluid therapy via an intravenous injection decreased serum levels of ammonia and liver enzymes in cases 1 and 2. Further, additional oral ingestion of non-absorbable disaccharide lactulose to eliminate intestinal nitrogenous products enabled recovery of two oryxs. However, in case 3, the serum levels of ammonia and liver enzymes increased even after treatment, and the oryx died. Necropsy revealed cecum and colon compaction due to stiff dried feces, and this condition could have an adverse effect on increased blood ammonia levels that may have caused mortality. Overconsumption of pellets may have been the primary cause of hepatic encephalopathy. Thus, a fiber rich diet with decreased amount of pellets is needed to prevent hepatic encephalopathy, since the normal diet of scimitar-horned oryxs is rich in fiber.