New paper reports the first flunixin-associated mortality of a Gyps vulture in Asia
The paper “First documented case of flunixin residue in a Himalayan Vulture Gyps himalayensis Hume, 1869 (Aves: Accipitriformes: Accipitridae) in India: conservation and veterinary implications” (see here), published in the Journal of Threatened Taxa on 26th September 2025, provides evidence for the first case of flunixin poisoning in Asian Gyps vultures, demonstrating that, despite more than two decades of NSAID regulation in the region, toxic veterinary drugs still pose a serious threat to vulture populations in South Asia.
It is almost 20 years since the governments of India, Pakistan and Nepal banned the veterinary use of the non-steroidal anti-inflammatory drug (NSAID) diclofenac due to the drug’s impact on vulture populations, with three species of Gyps vulture declining by more than 95% in little more than a decade in India. However, it has been well-documented that other vulture-toxic NSAIDs have replaced diclofenac to some extent in the veterinary market, but it has not been until recently that similar bans have been put in place in India (the most important country in the region for vultures) for any of these other drugs (aceclofenac and ketoprofen in 2023 (banned nationwide in Bangladesh in 2021) and nimesulide in 2024), despite strong and long-standing evidence for their toxicity to vultures.
The new paper details the case of a Himalayan Vulture Gyps himalayensis that was found in a weakened state and taken to the Buxa Vulture Conservation Breeding Centre & Aviary at Rajabhatkhawa (West Bengal) where, despite treatment, the bird died. During the necropsy, typical signs of visceral gout, i.e. a coating of the organs with uric acid crystals, was noted, suggesting the bird had died from kidney failure. Toxicological analysis confirmed the presence of flunixin residues in the liver, kidney and stomach of the dead bird. This combination is typical of the symptoms of NSAID poisoning in vultures and suggests that it is highly likely that the bird died of flunixin poisoning, the drug likely consumed when the vulture was feeding on a carcass of a domesticated animal that had been given the drug shortly before death.
Presence of visceral gout characterised by extensive deposition of uric acid crystals on the liver of the rescued Himalayan Vulture’s carcass (Chakraborty et al. 2025 ©Buxa Vulture Conservation Breeding Centre & Aviary).
Evidence has been building that flunixin is likely toxic to vultures, with both captive and wild birds of a closely-related species showing similar signs of visceral gout and flunixin residues being found in Europe and Israel (Zorilla et al. 2014, Eleni et al. 2019, Herrero-Villar et al. 2020; N. Anglister pers. comm.). This paper highlights that the drug is likely killing vultures in Asia, too. Recent evidence from undercover pharmacy surveys across South Asia has shown that flunixin is becoming increasingly popular for use by livestock owners with sick or injured cattle; it therefore needs to be experimentally tested, and if proven toxic, subject to similar veterinary bans to prevent it from reaching vultures’ food. The Indian Veterinary Research Institute (IVRI) has plans to test the safety of flunixin on vultures, and this latest paper highlights the how urgent such testing has become.
Lead author Soumya Chakraborty said “Although Buxa is primarily a vulture breeding centre, we have rehabilitated several dozen Himalayan Vultures over the years, releasing them back into the wild, hopefully to return to their high-altitude breeding grounds. Although it is sad that this bird did not survive, the information that we have obtained, highlighting the role that flunixin played in its death, will be vital for the future conservation of vultures across the region”.
Professor Rhys Green from the University of Cambridge and Royal Society for the Protection of Birds (RSPB), and former chair of SAVE, commented “This paper provides yet more evidence that flunixin is toxic to vultures. Governments in vulture-range states, such as India, need to fulfil their obligations under the Convention on Migratory Species, which includes ensuring that all NSAIDs available for veterinary use are tested before their use is approved and, if already approved, banned if found to be toxic”.
Compiled by John Mallord
References
Chakraborty, S.S., Ray, D., Sen, A., Harikrishnan, P.J., Jha, N.K. and Ghosh, R. 2025. First documented case of flunixin residue in a Himalayan Vulture Gyps himalayensis Hume, 1869 (Aves: Acciptriformes: Acciptridae) in India: conservation and veterinary implications. J. Threat. Taxa. 17, 27517-27522.
Eleni, C., Neri, B., Giannetti, L., Grifoni, G., Meoli, R., Stravino, F., Friedrich, K.G., Scholl, F., Di Cerbo, P. and Battisti, A. 2019. Death of captive-bred vultures caused by flunixin poisoning in Italy. Environ. Toxicol. Pharmacol. 68, 91-93
Herrero-Villar, M., Velarde, R., Camarero, P.R., Taggart, M.A., Bandeira, V., Fonseca, C., Marco, I. and Mateo, R. 2020. NSAIDs detected in Iberian avian scavengers and carrion after diclofenac registration for veterinary use in Spain. Environ. Poll. 266, 115157
Zorilla, I., Martinez, R., Taggart, M.A. and Richards, N. 2014. Suspected flunixin poisoning of a wild Eurasian Griffon Vulture from Spain. Conserv. Biol. 29, 587-592