Zinc Poisoning in a Hyacinth MacawZinc Poisoning in a Hyacinth Macaw
Gillian Willis, a toxicologist who does volunteer work with an avian veterinarian in Vancouver, B.C., Canada, recently was consulted on a case of a 3-year-old, hand-raised, male hyacinth macaw who had loose, foul-smelling stools, anorexia, weight loss, lethargy, depression, ataxia, and impaired vocalizations of 4 days' duration. He had refused food and water for 24 hours and his clinical condition was deteriorating rapidly.
The bird was housed alone in a cage and lived in the family room with 14 other healthy parrots. His diet consisted of a variety of nuts, monkey chow, fruits, vegetables and table food. When healthy, he was in the habit of rocking his cage, running his beak up and down the chrome-plated cage bars and occasionally snapping them off. Over the previous 6 months, he had destroyed three different cage door padlocks.
When he was brought in for examination, the bird was lying down, fluffed, depressed and severely dehydrated. He was thin and had voluminous, foul-smelling, bright lime-green feces with normal urates and urine. The vet's differential diagnosis included heavy metal poisoning (especially lead or zinc). Samples of blood, feces, and choanal and cloacal smears were taken for laboratory analysis.
The bird was treated initially with lactated Ringer's solution (IV and SC) and antibiotics and was placed in a hospital cage where he was given oxygen. He responded to supportive care and was able to stand and drink within 6 hours, but remained anorexic. He was tube fed and started on antifungal therapy. After 20 hours of hospitalization, the bird was stable enough to have x-rays taken. These revealed a metallic object measuring approximately 6 x 2 x 2 mm in his ventriculus. Laboratory results showed markedly high plasma zinc concentrations (24 ppm). Chelation therapy to bind the zinc and laxatives to hasten the passing of the metallic object were given. The vet decided not to surgically remove the foreign body because of the bird's weakened condition and because the object was small enough to pass.
By the morning of the third day, the bird was eating, drinking and vocalizing. He was discharged home with instructions to continue with chelation therapy, laxatives, antibiotics and an antifungal drug.
When re-examined 12 days after admission, the bird was clinically normal and had gained weight. An x-ray showed that the metallic object had passed. Plasma zinc had dropped to 1.5 ppm (normal range). He continued to improve and, 40 days after admission, had continued to gain weight (26 - increase). Plasma zinc had dropped to 1.0 ppm.
The potential sources of zinc were the destroyed padlocks and the chrome-plated cage bars. Analysis showed that the padlocks contained zinc, steel, brass and nickel and that the cage bars also contained zinc. Zinc is extremely toxic to birds. Sources include galvanized cage wire, quick links, clips or staples, bird toy snaps, zippers, keys, nails, plumbing nuts, nuts on animal transport cages, hardware cloth, padlocks, some anti-rust paints, shampoos and skin preparations.
Your choice of cage or cage material will depend on the size of the bird(s) and its chewing habits. Electroplated zinc is safe and cannot be chewed off by birds. Galvanized wire cages must be washed off with a vinegar solution before use. Once treated, they are probably safe for smaller non-chewing birds. For larger birds that may chew on the galvanized wire, this material is probably best avoided. Zinc-containing paints on cages should be avoided. Padlocks are frequently used on bird cages. Other types of locking devices should be considered on the cages of large birds who may chew on padlocks.
Birds can make a complete recovery from zinc poisoning as long as they receive appropriate therapy
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