May 12, 2011

Dwindling South Asian Vultures See Hope Of Survival

The banning of a painkiller that causes visceral gout, a fatal kidney ailment in vultures, has shown first signs of progress in the populations of South Asian vultures, according to scientists.

But the study warns that the death rate from the drug is still too high, and that the complete removal of the painkiller, diclofenac, is needed to see further recovery of the wild vulture populations.

Veterinary use of diclofenac in the treatment of cattle and buffaloes was banned in 2006 by India, Nepal and Pakistan when it was found that the drug had lethal effects on vultures that fed on the carcasses of the domesticated animals that were treated with the painkiller shortly before they died.

Britain's Royal Society for the Protection of Birds (RSPB) studied more than 4,500 liver samples of cattle and buffalo carcasses at 21 sites across India.

Between 2006 and 2008, the study showed that the proportion of cattle carcasses in India contaminated with the drug declined by over 40%, with the concentration of the drug in contaminated animals falling as well.

The study found that by 2007-2008, estimated death rates of vultures "had slowed appreciably," a welcome sign for conservationists working to save these birds in South Asia.

On the Indian sub-continent, three species of vultures are found "“ the oriental white-backed vulture, the long-billed vulture and the slender-billed vulture, which are collectively known as gyps vultures.

After the introduction of diclofenac in the mid-1990s to treat colic in cattle, whose carcasses were left in the open after they died to become food sources for the scavengers, the vulture population decreased as much as 95 percent, reports AFP.

In fact, the Bombay Natural History Society conservation group estimated that there were only about 11,000 white-backed, 1,000 slender-billed and 44,000 long-billed vultures left in India, according to their study in 2007.

A human version of diclofenac is still available on the market. However, it is now illegal to import, manufacture, sell or use the painkiller for veterinary purposes in India.

The findings in the study are "encouraging" but scientists believe that the continued deaths from diclofenac were of "major concern" because it suggests that the drug is being used illegally.

In order to prevent the number of vultures being poisoned from creeping back up, the illegal use of the painkiller must be eradicated.

"Because of the difficulty in ensuring that human diclofenac is not being used illegally and in secret, testing the vulture food (cattle carcasses) directly is the only way to find out how safe the vultures really are," says co-author and former Research Director of the Indian Veterinary Research Institute Dr. Devendra Swarup.

Other painkillers have replaced diclofenac, but some have proven just as fatal to vultures.

Currently, the only safe alternative to the deadly painkiller is meloxicam, which has been more widely used ever since its cost has fallen close to match that of diclofenac, says the study.

Lead author, Dr. Richard Cutbert of RSPB, says, "This shows how much progress has been made, but there is still a job to do to make sure that safe alternative drugs are used. Unfortunately some of the alternatives have not been tested for their safety to vultures and one drug in increasing use, ketoprofen, is already known to be toxic to vultures."

The results of the study were published May 11 in the journal PLoS ONE.


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