The race to prevent the extinction of South Asian vultures

Abstract

Gyps vulture populations across the Indian subcontinent collapsed in the 1990s and continue to decline. Repeated population surveys showed that the rate of decline was so rapid that elevated mortality of adult birds must be a key demographic mechanism. Post mortem examination showed that the majority of dead vultures had visceral gout, due to kidney damage. The realisation that diclofenac, a non-steroidal anti-inflammatory drug potentially nephrotoxic to birds, had become a widely used veterinary medicine led to the identification of diclofenac poisoning as the cause of the decline. Surveys of diclofenac contamination of domestic ungulate carcasses, combined with vulture population modelling, show that the level of contamination is sufficient for it to be the sole cause of the decline. Testing on vultures of meloxicam, an alternative NSAID for livestock treatment, showed that it did not harm them at concentrations likely to be encountered by wild birds and would be a safe replacement for diclofenac. The manufacture of diclofenac for veterinary use has been banned, but its sale has not. Consequently, it may be some years before diclofenac is removed from the vultures' food supply. In the meantime, captive populations of three vulture species have been established to provide sources of birds for future reintroduction programmes.

Avian scavengers and the threat from veterinary pharmaceuticals

“…Meloxicam has been advocated to veterinarians, pharmacists and livestock owners as an alternative NSAID that is safe for vultures when used in place of diclofenac since 2006 [23]. Consequently, if the observed decline in diclofenac prevalence in carcasses was due to substitution with meloxicam, we would expect site-clusters with the largest decrease over time in diclofenac prevalence to be those with the largest increase in meloxicam.…”

Diclofenaco en buitres: ¿podría provocar el declive de la población española?

“…La DL50 estimada en buitres se encuentra entre 0.098-0.225 mg/Kg (Swan et al 2006a), por lo que la ingesta de carcasas tratadas con este fármaco poco antes de su muerte provoca toxicidad en buitres. En las carcasas, las concentraciones más altas de diclofenaco se encuentran en intestino, hígado y riñón, coincidiendo con los órganos más apetecibles para estas aves (Taggart et al 2007;Pain et al 2008;Green et al 2006).Además, en ciertas áreas del sur de Asia hay prácticas religiosas que prohíben la eutanasia en vacas, utilizando el diclofenaco como agente paliativo para aliviar el dolor de los animales que poco después morirán. El zoroastrismo, práctica religiosa que se lleva a cabo en ciertas regiones del continente asiático, defiende que los animales muertos deben exponerse al sol para alimentar a los buitres u otros animales salvajes (Gross 2006;Swanet al 2006b;Pain et al 2008).…”

“…En las carcasas, las concentraciones más altas de diclofenaco se encuentran en intestino, hígado y riñón, coincidiendo con los órganos más apetecibles para estas aves (Taggart et al 2007;Pain et al 2008;Green et al 2006).Además, en ciertas áreas del sur de Asia hay prácticas religiosas que prohíben la eutanasia en vacas, utilizando el diclofenaco como agente paliativo para aliviar el dolor de los animales que poco después morirán. El zoroastrismo, práctica religiosa que se lleva a cabo en ciertas regiones del continente asiático, defiende que los animales muertos deben exponerse al sol para alimentar a los buitres u otros animales salvajes (Gross 2006;Swanet al 2006b;Pain et al 2008). No se debe olvidar que el diclofenaco era muy utilizado por los veterinarios debido a su bajo precio y su alto poder como antiinflamatorio, siendo administrado a los animales en grandes dosis mediante bolos orales (Cuthbert et al 2011).…”

Merging Wildlife and Environmental Monitoring Approaches with Forensic Principles: Application of Unconventional and Non-Invasive Sampling in Eco- Pharmacovigilance

“…The role of the NSAID diclofenac in reducing populations of three Gyps vulture species on the Indian subcontinent from many tens of millions to <1-2 % of their original levels -the 'Asian vulture crisis', has been extensively documented and discussed elsewhere [91]. In summary, vultures were widely exposed to residues of diclofenac when they fed on livestock carcasses disposed of in carcass dumps; a common historical practice that artificially inflated Gyps populations, especially in parts of Asia dominated by Hinduism, which considers the cow as sacred and does not permit beef consumption.…”