Indian Veterinary Research Institute-led study identifies a second non-steroidal painkiller for animals that is also safe for vultures

Published : September 24, 2021 13:14 IST

IVRI and BNHS scientists giving a vulture an oral dose of tolfenamic acid. Photo: Chris Bowden, RSPB

There’s some good news for vultures. A second vulture-safe veterinary painkiller has been identified and proved to be safe for them. The veterinary use of diclofenac, a non-steroidal anti-inflammatory drug (NSAID), turned out to be fatal for vultures that feed on dead animals that were treated with the drug for providing immediate relief. However, in 2003 a study found that residual build-up of the drug in the vital organs of the animal ultimately killed it, and the vultures that ate these animals also ended up dead. This led to the testing of other drugs to determine how safe they were, and in 2006 one of the drugs, meloxicam, was found to be effective on cattle and safe for vultures too.

Now a second drug has been identified as safe for vultures. A press note from the Royal Society for the Protection of Birds (RSPB) announced with muted rejoicing that “it is hugely significant that a systematic safety testing study led by the Indian Veterinary Research Institute (IVRI) with the Bombay Natural History Society (BNHS) and the Royal Society for the Protection of Birds has identified tolfenamic acid as the second confirmed vulture-safe NSAID after meloxicam.”

To test tolfenamic acid, 38 Himalayan griffon vultures were caught from the wild and, along with a captive bred white-rumped and long-billed vulture, administered doses of tolfenamic acid by oral gavage. This essentially meant that the drug was fed directly into the lower oesophagus or stomach through a feeding needle also known as a gavage. It is threaded through the mouth down the oesophagus and into the stomach. The amount given was “the maximum possible level likely to be encountered by birds feeding on carcasses in the wild. This was calculated based on concentrations of diclofenac found in cattle carcasses in India, which showed that vets and livestock owners routinely give doses of this drug much higher than the recommended level. In addition, four Himalayan griffons were also fed buffalo meat from animals given double the recommended dose of tolfenamic acid just prior to death.”

Two of the griffons died as a result of the experiment. All the other birds were monitored for an increase in uric acid and kidney failure, which is the usual sign of NSAID poisoning. “These findings show that tolfenamic acid is safe to wild vultures at levels of the drug that they are likely to be exposed to,” says the RSPB. The note says, “Tolfenamic acid is already licensed and produced by a number of different Indian manufacturers, being out of patent, and similarly priced to other drugs.”

Quoting Chandra Mohan, Scientist of IVRI and lead investigator of the study, the press note says, “Every painkiller available has slightly different properties, and the vets often complained of not having a second choice of NSAIDs. But we are very pleased to report that tolfenamic acid been found as a second safe NSAID drug.”

Vibhu Prakash, Principal scientist and vulture programme Director of BNHS, explained via the briefing note that “by testing first on the less threatened Himalayan griffon vultures, we could establish the comparative safety of the drug. We then also tested it on the most threatened species held at the breeding centre at Pinjore, Haryana.”

Similarly, Dr A.M. Pawde, Incharge, Centre for Wildlife, IVRI, and Dr M. Karikalan, Scientist at the IVRI centre, said, “IVRI is particularly pleased to help identify this safe alternative for veterinarians, and it is important that this information is made available quickly to avoid use of other more toxic alternatives (for the vultures) becoming popular in veterinary use.” They added, “Tolfenamic acid does have certain properties which make it slightly more similar to diclofenac in its ability to reduce fever as well as inflammation, and this may be important in being taken up more widely by vets across the country.”

Triveni Dutt, Director of IVRI, commented in the press note that “this is good news for vulture conservation and can help decision-makers take important steps towards banning the NSAIDs which are proven to be toxic, such as aceclofenac and ketoprofen.”

And, finally, Professor Rhys Green of Cambridge University, United Kingdom, and Chair of SAVE (Saving Asia’s Vultures from Extinction is a consortium of 24 partners), is quoted in the note as saying, “After sixteen years and considerable effort in safety testing NSAIDs on vultures we have found a second vulture-safe NSAID for use on cattle. This is important and welcome news. It will reduce the pressure to use toxic alternatives such as aceclofenac, ketoprofen, flunixin and nimesulide, which are still available and legally used in the region. Veterinary use of all of these toxic drugs should be banned immediately.”

Green added, “So this is highly significant, and good news for vulture conservation, but only if it helps decision-makers to take more urgently needed action to remove licences for similar drugs that are proven to be toxic, such as aceclofenac and ketoprofen. Neighbouring Bangladesh has earlier this year taken this important and commendable step to extend local ketoprofen bans to national bans, and if India can do this for aceclofenac and ketoprofen, this will be real progress.”

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