Abstract
Public walk-through lory and lorikeet aviaries remain a popular exhibit in U.S. zoological parks. From a veterinary perspective, these exhibits can be “high-maintenance” with relatively high morbidity and mortality. In addition to trauma secondary to conspecific aggression, a variety of infectious disease problems have been reported.1 The Louisville Zoo has observed a high incidence of hepatopathy in its lorikeet flock with 15/34 (44%) pathology cases having histologic evidence of acute or chronic hepatic degeneration, hepatitis, necrosis, and/or fibrosis/cirrhosis. Affected birds may present with lethargy, anorexia, weight loss, regurgitation, central nervous system signs, and/or hypoalbuminemia and ascites. A chronic hepatopathy has been recently presented as a wide-spread disease problem in numerous birds from multiple U.S. facilities.1 An etiology has not been identified but nutritional issues, or exposure to a hepatotoxin or virus is suspected.
Loriinae are reported to naturally consume a diet high in vitamin A precursors (i.e., carotenoids like beta-carotene) rather than foods high in preformed vitamin A.4-6 Excessive vitamin A (>1000 IU/kg) in captive diets has been implicated to lead to health problems including infertility, beak and feather pigmentation abnormalities, and immunosuppressive disease.4-6 Diet analysis demonstrated that the diet fed to birds at the Louisville Zoo had high levels of vitamin A. Liver analyses of affected birds revealed that hepatic vitamin A concentrations were elevated when compared to the limited data available for wild Loriinae. Vitamin A is a documented hepatotoxin.2,3 Studies are on-going, but we suggest that dietary vitamin A excess may contribute to hepatopathy in this taxon.
Literature Cited
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