Drug Residue In Cows Is Killing Vultures

by Patricia Collier

The populations of three species of vultures have been decreasing since the early 1990s and scientists say they are dying because of a veterinary drug used to reduce fever and treat lameness in farm animals.

Conservationists first thought the deaths were caused by a new bird plague, but an international research team found chalky deposits in the birds' internal organs, showing the birds were dying of kidney failure.

After checking livestock pharmaceuticals for those harmful to birds, researchers have placed blame on the drug Diclofenac.

Used extensively with cows in Pakistan and India, Diclofenac is not as popular with veterinarians in the United States. It is, however, a common treatment in the U.S. for arthritis and pain in humans.

The deaths have affected the oriental white-backed, the slender-billed, and the long-billed vultures, and ecological effects are already being felt.

"All three [vulture] species will likely become extinct in the wild within five years," said coauthor Rick Watson of the Peregrine Fund in Boise, Idaho, one of the sponsors of the research.

Watson said vultures quickly consume dead animal carcasses, helping to prevent the spread of anthrax and foot-and-mouth disease.

According to ornithologist André Dhondt at the Cornell Laboratory of Ornithology in Ithaca, New York, if carcasses are not eaten by vultures, the number of foxes will increase, and so will the prevalence of rabies.

The team's conclusion was that Diclofenac caused acute kidney failure in the vultures when they ate the carcasses of animals that had recently been treated with it. Their findings were recently published online by the journal Nature.

Dr. J. Lindsay Oaks, an assistant professor of veterinary medicine at Washington State University was the primary author of the report. According to Oaks, the crisis with the vulture populations is the first time major ecological damage has been shown to be caused by a pharmaceutical product.

Oaks said scientists and environmentalists have been increasingly concerned about the "vast amount of drugs that end up in the environment one way or another."

A 2002 study by the United States Geological Survey found traces of several different pharmaceuticals and "personal care products" -- including steroids, insect repellents and others -- in the American water supply.

Thomas E. Lovejoy, president of the H. John Heinz III Center for Science, Economics and the Environment, noted that, while the effect of such traces is unknown, the concern is about the unexpected.

"I think what it actually says is that we really need to look systematically at the use of pharmaceuticals for veterinary purposes," Dr. Lovejoy said.

"It does raise a question of whether we should be looking more closely at the trace chemicals from human use," he added.

© 2004 Animal News Center, Inc.