In spring of 2005, six of 10 brown pelicans (Pelecanus occidentalis) died or were euthanatized within 8 weeks of being moved from winter holding onto outdoor lake exhibits. Clinical signs included weakness and inability to stand or hold wings in normal posture. Laboratory analyses included CBC, plasma biochemicals, minerals and zinc concentrations, blood lead, West Nile and Chlamydophila serology, plasma vitamin A, D and E concentrations and radiographs.
Necropsies included gross exam, histopathology, virology, toxicology, vitamin determinations, and cultures. Significant findings were severe generalized myopathy. Lesions in striated muscle were mild to moderate atrophy, degeneration and necrosis of up to 90% of the skeletal musculature. No infectious or toxic agents were found. Two other piscivorous birds died with similar signs. A boat-billed heron (Cochlearius cochlearius) had necrotizing steatitis and mild, multifocal degeneration, necrosis, and mineralization of skeletal muscle; and an adjutant stork (Leptoptilos javanicus) had mild to moderate, multifocal to regionally extensive loss of myocytes with replacement by fibrous connective tissue in the heart.
Food items were analyzed for vitamin E levels. The product (Thiamin E, Stuart Products, Inc., Bedford, TX, USA) that had been used to supplement fish, was found to have been lacking in adequate vitamin E for greater than 9 months. An error in manufacturing was identified by the producer, and measures were taken to immediately correct the problem. Subsequent analyses of two samples, conducted in August 2005 and March 2006, at different laboratories confirmed that the concentration of vitamin E in the newly manufactured product met its label guarantee. This experience underscores the importance of periodic review and laboratory analysis of dietary items used in a zoo feeding program.