Abstract
L ead intoxication or plumbism is one of the most common poisonings of companion and wild birds. Birds are very inquisitive and frequently investigate objects in their environment. Parrots especially have a tendency to chew on almost anything in their reach.
Lead may be found in numerous places in the home. Common sources of lead include curtain weights, fishing and boating accessories, batteries, solder, certain ceramic glazes, costume jewelry, foils on wine and champagne bottles, lead paint and drying agents, antique or imported cages, Tiffany lamps and stained glass. Certain toys for
small birds such as rolling penguins contain lead weights. If a larger bird breaks these open, it is able to ingest the lead.
Lead damages the nervous system, bone man-ow, liver, gastrointestinal tract and kidneys. Clinical signs of lead intoxication depend upon the species of bird, the amount of lead ingested, the period of exposure, and the material present in the gizzard.
Lead poisoning may be acute with the ingestion of a large amount of lead at one time or chronic with accumulation over weeks to months. Ingested lead is degraded by the stomach acids and absorbed into the bloodstream.
Some lead is retained in the soft tissues and hone man-ow. Excretion occurs by the kidneys over months.
A variety of signs may occur depending upon the species and whether exposure is acute or chronic. Acutely exposed birds may die suddenly with little to no signs of toxicity or they may develop regurgitation, appetite . loss, depression, weakness and abnormal droppings. Neurological signs including head tremors, twitching, balance difficulties, circling, wing droop, leg paresis and convulsions may occur. Amazons and African Greys may pass loose bloody droppings.
Birds suffering from chronic lead
poisoning often regurgitate, and lose weight. Paresis, paralysis and blindness may be present. Diagnosis is hased upon clinical signs, radiographs, and blood lead levels. Lead should he considered as part of the differential diagnosis of any ill hird, especially if it is allowed to roam freely in the home. Radiographs may reveal the presence of metallic densities in the digestive tract. Not all metal densities are lead and not seeing metallic densities does not rule out lead poisoning. Some lead-containing ohjects such as paint chips are not radio-dense. Clinical signs can occur when lead previously sequestered in bone marrow moves into the blood. Blood lead levels may be determined. Anytime a suspicion of lead toxicity occurs, treatment should be initiated.
After the bird is stabilized, chelating agents such as CaEDT A are administered to remove lead circulating in the blood. A dramatic improvement often occurs within a short period of time in birds suffering from acute lead poisoning. Small metal fragments present in the gizzard may pass with oral administration of lubricating agents such as cellulose or peanut butter. Epson salt combined with activated charcoal acts as a cathartic and will prevent further absorption of lead from the gastrointestinal tract. Large metallic pieces may require removal by endoscope or gastric lavage.
Seizures are controlled with valium and the bird is supported with fluids, tube feeding, and heat. Blood levels are monitored over several weeks and radiographs are taken periodically to ensure that the lead is removed.
In addition to lead, zinc intoxication is becoming increasingly more common in caged birds. Sources of zinc include galvanized wire, hardware cloth, certain washers, nuts, and snapon fasteners, and some pennies. Signs are very similar to those in lead poisoning and fortunately the diagnosis and treatment are similar.
Chronic exposure may occur with birds exposed to fine zinc powder on the surfaces of their cages if the cages are treated with zinc coating. This powder is not radiographically visible.
The best way to prevent lead and zinc toxicity is to "birdproof" your bird's environment.