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.
1. Garner MM. A retrospective study of diseases in captive lories and lorikeets. Assoc Avian Vet. 2008;65.
2. Hilton JW. Hypervitaminosis A in rainbow trout (Salmo gairdneri): toxicity signs and maximum tolerable level. J Nutr. 1983;113:1737–1745.
3. Kowalski TE, Falestiny M, Furth E, Malet PF. Vitamin A hepatotoxicity: a cautionary note regarding 25,000 IU supplements. Am J Med. 1994;97:523–528.
4. McDonald D, Oldfield T. Suspected hypervitaminosis A in lorikeets maintained on commercially formulated nectars: a case study. In: Proceedings Assoc Avian Vet Aust Comm. 2003;43–54.
5. McDonald D, Oldfield T. Dietary vitamin A requirements of lorikeets: how much is too much? In: Proceedings Assoc Avian Vet Aust Comm. 2004;83–86.
6. Park F. Vitamin A toxicosis in a lorikeet flock. Vet Clin Exot Anim. 2006;9(3):495–502.