Palliative or poison?

Natural History, April, 2004 by Stephan Reebs

Vultures, the quintessential garbage collectors, were a familiar sight in South Asia just a decade ago--particularly the Oriental white-backed vulture, Gyps bengalensis. But sometime in the 1990s they began dying off at an alarming rate. So J. Lindsay Oaks, a veterinarian at Washington State University in Pullman, and a team of colleagues decided to do a few hundred necropsies in Pakistan. What they found was widespread evidence of acute kidney failure, probably caused by the ingestion of something toxic.

Arsenic, cadmium, copper, lead, mercury, pesticides, viruses, other infections--you name it, they tested for it and ruled it out. The actual culprit was a substance frequently present in the carcasses of dead livestock, the vultures' normal food source.

Nowadays, sick buffalo, cattle, and goats are often given diclofenac, a nonsteroidal anti-inflammatory drug that has become available in Pakistan in the past five years. Virtually every veterinarian and drug retailer sells it. Oaks and his team say the drug is the reason not merely for isolated cases of poisoning among scavengers, but for the near disappearance of the entire G. bengalensis species from the Indian subcontinent. ("Diclofenac residues as the cause of vulture population decline in Pakistan," Nature 427: 630-32, February 12, 2004)