Common Heavy Metals – Lead and Zinc
There are many potentially toxic substances in our birds’ environment, but lead and zinc toxicities are two of the most common and the most life-threatening. Zinc can be found in a number of metal structures including some wire cages (especially galvanized wire), wire toy clips, household washers and nuts, zippers, and some pennies. Lead is common in old linoleum, old paint, solder, some fishing equipment, costume jewelry, curtain weights, chandeliers, shotgun pellets, and stained glass. Often, owners are not even aware that their birds have been exposed to these substances.
Clinical signs can be similar with both lead and zinc, and can vary depending on the amount of the heavy metal that has been ingested. Mentation changes (depression or hyperexcitability), neurological signs (weakness, difficulty walking or perching, seizures, drooping wings), gastrointestinal signs (diarrhea, regurgitation, appetite changes), and urinary signs (increased water consumption, increased urination, and/or green, red, or brown urine) are the most common clinical signs that owners notice. Zinc ingestion has been reported to cause feather picking or mutilation in some birds, but this correlation has never been proven.
The diagnosis of lead or zinc toxicity begins with a complete medical history and a thorough physical examination. A minimum data base consisting of a complete blood count, a chemistry profile, and x-rays is essential. Most birds with heavy metal toxicity will have varying degrees of anemia, changes in white blood cell counts, and evidence of metallic fragments in the gastrointestinal tract on x-rays. A lead and zinc level must be submitted to confirm the diagnosis and establish a baseline to evaluate the effectiveness of therapy. Often, results aren’t available for several days and treatment must be started based on the presumptive diagnosis.
Treatment for lead or zinc toxicity includes 1) stabilizing the patient and initiating basic supportive care, 2) removing any pieces of metal from the gastrointestinal tract, and 3) chelating or binding the lead or zinc already in the body. Initial supportive care may include fluid therapy, nutritional support, a heated environment, treatment of secondary infections, and blood transfusions if necessary. Calcium ethylenediaminetetraacetate (CaEDTA) is the most commonly used chelating agent and must be given as twice daily injections for at least 4-5 days. Additional therapy is based on response to this initial course and may include further injections or the addition of an oral chelating agent. Psyllium or peanut butter can be used in an attempt to encourage the metal fragments to pass. Rarely, surgical or endoscopic retrieval is necessary. Depending on the situation, some birds require hospitalization for days to weeks.
Because heavy metal toxicity is both life-threatening and expensive to treat, it is important to prevent your bird from ingesting these substances. Avoid contact with any unknown metal sources or any of the objects listed above. Your bird should never be allowed to roam around the house unsupervised. If you suspect that your bird is showing any unusual clinical signs, you should consult your avian veterinarian immediately.
Content prepared by St. Francis Animal and Bird Hospital, 1227 Larpenteur Ave. West, Roseville MN. 55113