| Zinc is an essential
trace metal. In birds, ingestion of excessive amounts of zinc results in
toxicity resembling lead intoxication. Although not a common as lead intoxication,
zinc poisoning is an important differential in a lethargic, depressed bird
with loose, voluminous, malodorous, pale or brilliant lime-green feces.
Other common signs of zinc toxicity in birds include anorexia, weight loss,
dehydration, polyuria, polydipsia, ataxia, posterior paresis, and anemia.
Hyperglycemia, seizures, and cyanosis, have also been reported in zinc-poisoned
birds. Vomiting was reported in one green-winged macaw (Ara chloroptera)
with zinc toxicity. Sources of zinc include galvanized cage wire and containers,
cage clips or staples, bird toy snaps, zippers, US pennies minted after
1982, keys, nails, plumbing nuts, nuts on transport cages, and hardware
cloth, as well as some paints, fertilizers, shampoos, skin preparations,
and suppositories formulated with zinc. Zinc is absorbed in the proventriculus
and the small intestine of chicks. In experimentally intoxicated chicks
and cockatiels, zinc distributes to various tissues (eg. liver, kidney,
and plasma), but the pancreas is the target organ. Focal mononuclear cell
infiltrates and degeneration have been reported in the acini of the exocrine
pancreas as well as in the liver and kidneys of zinc-poisoned birds. In
addition to the pancreas, liver, and kidneys, the reproductive and gastrointestinal
systems are also directly affected
by zinc. |
