Heavy metal toxicoses in pet birds: Watch for combination of gastrointestinal and nervous systems signs - DVM
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Heavy metal toxicoses in pet birds: Watch for combination of gastrointestinal and nervous systems signs


Zinc toxicosis, also know as "new wire disease", is also reported in avian species and should always be included in the same differential list with lead if heavy metal intoxication is suspected. Sources of zinc are numerous and include galvanized mesh and metal clips, hardware cloth, staples, galvanized nails or wire, galvanized feed and water containers, fertilizers, some paints, zinc pyrithione shampoos, zinc oxide, zinc undecylenate (Desenex cream) and pennies (post 1982). Depending upon the type, some galvanized coatings may contain 99.9 percent zinc while others may contain 98 percent zinc and 1 percent lead.It should be noted that fumes from welding galvanized materials may also contain zinc, lead or iron.

Clinical signs of zinc toxicosis are similar to those seen with lead and include polyuria, polydipsia, weight loss, diarrhea, weakness, vomiting, anemia, cyanosis and hypoglycemia. Systemic effects are associated with damage to the kidneys, gastrointestinal tract and pancreas.

The diagnosis of zinc toxicosis requires a complete clinical history, physical examination, radiology and demonstration of elevated blood (serum) or tissue (pancreas) zinc levels. Radiographs may demonstrate metallic densities within the gastrointestinal tract; however, toxicosis may be present without identifiable metallic densities within the esophagus, crop, stomach or lower gastrointestinal tract. Samples used for blood zinc analysis should be collected in glass or all-plastic syringes and tubes. Rubber stoppers on serum tubes and the grommets on some plastic may artifactually elevate the zinc levels in the collected sample. Serum tubes with royal blue stoppers are free of zinc and are the most appropriate for collecting samples for analysis. Blood zinc levels greater than 200 microgram/dl (2.0 ppm) are diagnostic for zinc toxicosis. Tissue levels greater than 1,000 microgram/g are also suggestive of zinc toxicosis.

Treatment of zinc toxicosis is similar to that used for lead toxicosis. Zinc is not stored in the bone and therefore, equilibrates and chelates faster than lead. The incidence of "new wire disease" may be decreased by scrubbing galvanized wire with vinegar.

Dr. Jones is associate professor of avian and zoological medicine at the University of Tennessee's College of Veterinary Medicine. He is a diplomate of the American Board of Veterinary Practitioners — Avian Specialty. Dr. Jones' clinical interests include raptor medicine, orthopedic and soft-tissue surgery, avian nutrition and avian infectious diseases. He is also a master falconer with 15 years experience.


Source: DVM360 MAGAZINE,
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