Removing the Threat of Diclofenac to Critically Endangered Asian Vultures

Abstract

Veterinary use of the nonsteroidal anti-inflammatory (NSAID) drug diclofenac in South Asia has resulted in the collapse of populations of three vulture species of the genusGyps to the most severe category of global extinction risk. Vultures are exposed to diclofenac when scavenging on livestock treated with the drug shortly before death. Diclofenac causes kidney damage, increased serum uric acid concentrations, visceral gout, and death. Concern about this issue led the Indian Government to announce its intention to ban the veterinary use of diclofenac by September 2005. Implementation of a ban is still in progress late in 2005, and to facilitate this we sought potential alternative NSAIDs by obtaining information from captive bird collections worldwide. We found that the NSAID meloxicam had been administered to 35 captiveGyps vultures with no apparent ill effects. We then undertook a phased programme of safety testing of meloxicam on the African white-backed vultureGyps africanus, which we had previously established to be as susceptible to diclofenac poisoning as the endangered AsianGyps vultures. We estimated the likely maximum level of exposure (MLE) of wild vultures and dosed birds by gavage (oral administration) with increasing quantities of the drug until the likely MLE was exceeded in a sample of 40G. africanus. Subsequently, sixG. africanus were fed tissues from cattle which had been treated with a higher than standard veterinary course of meloxicam prior to death. In the final phase, ten Asian vultures of two of the endangered species(Gyps bengalensis,Gyps indicus) were dosed with meloxicam by gavage; five of them at more than the likely MLE dosage. All meloxicam-treated birds survived all treatments, and none suffered any obvious clinical effects. Serum uric acid concentrations remained within the normal limits throughout, and were significantly lower than those from birds treated with diclofenac in other studies. We conclude that meloxicam is of low toxicity toGyps vultures and that its use in place of diclofenac would reduce vulture mortality substantially in the Indian subcontinent. Meloxicam is already available for veterinary use in India.

Avian scavengers and the threat from veterinary pharmaceuticals

“…Diclofenac and meloxicam concentrations in extracts were determined by liquid chromatography with electrospray ionization mass spectrometry (LC-ESI/MS). The limit of quantification (LOQ), back-calculated to concentration in wet tissue, was 0.01 mg kg 21 . Detailed protocols for extraction and analysis of these NSAIDs were reported previously [11,12].…”

The Pied Crow (Corvus Albus) Is Insensitive to Diclofenac at Concentrations Present in Carrion

“…Although this is theoretically possible using captive vultures, there are a large number of NSAIDs available, many of which may also be administered in combinations. Because most vulture species, including Gyps spp., are now regionally or globally endangered (IUCN, 2010), in vivo trials on all drugs or combinations are not feasible, especially given the large sample sizes required to prove drugs to be safe (as was the case for meloxicam; Swan et al, 2006a). One alternative would be to use a bird species that is common, widely distributed, easy to handle, and not endangered.…”

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

“…However, once conclusively implicated in the extensive vulture mortality, measures were taken (in 2006) to withdraw it from use within the veterinary sector and to identify an effective replacement that would not harm vultures. Rigorous safety trials identified meloxicam as a suitable alternative [92,93] and a campaign was then mounted to work with government authorities and pharmaceutical manufacturers. Banned (in India, Nepal and Pakistan) for veterinary use since 2006, the perception of diclofenac's efficacy nonetheless persists.…”