Toxicity of diclofenac to Gyps vultures

Abstract

Three endemic vulture species Gyps bengalensis , Gyps indicus and Gyps tenuirostris are critically endangered following dramatic declines in South Asia resulting from exposure to diclofenac, a veterinary drug present in the livestock carcasses that they scavenge. Diclofenac is widely used globally and could present a risk to Gyps species from other regions. In this study, we test the toxicity of diclofenac to a Eurasian ( Gyps fulvus ) and an African ( Gyps africanus ) species, neither of which is threatened. A dose of 0.8 mg kg −1 of diclofenac was highly toxic to both species, indicating that they are at least as sensitive to diclofenac as G. bengalensis , for which we estimate an LD 50 of 0.1–0.2 mg kg −1 . We suggest that diclofenac is likely to be toxic to all eight Gyps species, and that G. africanus , which is phylogenetically close to G. bengalensis , would be a suitable surrogate for the safety testing of alternative drugs to diclofenac.