June E. Olds1,2*, DVM; Steve Ensley3, DVM, PhD; Ronald Horst4, PhD; Eric Burrough3, DVM, PhD, DACVP; Darin Madson3, DVM, PhD, DACVP; Kent Schwartz3, DVM, MS; Gregory W. Stevenson3, DVM, PhD, DACVP; Phillip Gauger3, DVM; Bruce H. Janke3, DVM, PhD; Vicki L. Cooper3, DVM, MS, PhD; Paulo Arruda3, DVM, MS; Tanja Opriessnig3, Dr Med Vet, PhD
1Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, USA; 2Blank Park Zoo, Des Moines, IA, USA; 3Veterinary Diagnostic Laboratory, College of Veterinary Medicine, Iowa State University, Ames, IA, USA; 4Heartland Assays, Ames, IA, USA
In the spring of 2012, the Blank Park Zoo began suffering mortalities in a flock of 229 captive Budgerigars (Melopsittacus undulatus) housed in an interactive public-feeding aviary. Clinical signs included weakness, posterior paresis, inability to fly, central nervous signs or acute death. Gross and microscopic lesions were not apparent in acutely affected deceased birds. Many birds had evidence of trauma, but these traumatic events are now hypothesized to have been related to the birds’ weakness. Investigation into the cause(s) of morbidity and mortality were complicated by the recent opening of the new interactive enclosure, so environmental and husbandry sources were heavily scrutinized. Later in the course of the investigation, microscopic examination of tissues revealed mineralization of soft tissues consistent with hypervitaminosis D.1-5 Serum analysis of deceased birds also identified elevated vitamin D3 levels. Analysis of the formulated diet detected elevated levels of vitamin D3 22.5-times the manufacturer’s labeled content in the formulated feed (label=1800 IU/kg, actual=40,520 IU/kg). These findings eventually led to the manufacturer’s recall of over 100 diets fed to a wide variety of domestic and captive wild animals in the United States and internationally. This case report highlights the complexities of determining the etiology of a toxic event in a zoological institution.
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