Abstract
As a veterinary toxicologist and section head of the Toxicology Laboratory at the California Animal Health and Food Safety Laboratory System, I feel compelled to respond to Susan Boyer's article "Are you feeding your myna to death," published in your July/ August 2000 issue.
Mrs. Boyer correlated iron storage disease directly to the concentration of iron in food/feed. But the etiology of hemochromatosis in mynah birds is still not clear, and may not be diet induced. Studies have shown that iron storage disease in mynah birds shared most of the important histopathologic characteristics with idiopathic or hereditary hemochromatosis in man, and was not induced by dietary iron. Thus, the role of dietary iron in the development of iron storage disease has not been established. However, it is important to offer mynah birds appropriate, non-toxic concentrations of iron in their diet. As Mrs. Boyer pointed out, veterinary diagnostic laboratories offer testing for metal concentrations, and CAI-IFS is one of the service organizations in the Western US providing this service.
It is important to mention other factors affecting the absorption of iron from the gastrointestinal tract. Ascorbic acid (vitamin C) enhances the bioavailability of iron in avians. Citrus fruits and green leafy plants can contain large amounts of ascorbic acid and may lead to an increased uptake of iron. Therefore, feeding of citrus fruits can lead to increased absorption of iron.
Once a mynah bird is diagnosed with iron storage disease by a veterinarian, specific treatments have to be initi-
ated. It is correct that a diagnosis of hemochromatosis is often difficult and involves invasive techniques (liver biopsy ). But successful therapy is possible.
The data listed in Mrs. Boyer's article were only partly generated by the Toxicology Laboratory of CAHFS and were not part of a research study. The concentrations reported are based on one sample from each feed, and may not reflect representative and accurate sampling methods. The data can only be used as a guideline. If a diagnosis of hemochromatosis has been established in a bird, feed, fruit, water and other potential sources should be analyzed for iron in order to potentially reduce iron intake during treatment. Please note that a typographical error occurred in the article. The Kaytee Handfeeding Formula contained 485 ppm of iron, not 48 ppm as published in the article.