Experimental safety testing shows that the NSAID tolfenamic acid is not toxic to Gyps vultures in India at concentrations likely to be encountered in cattle carcasses.

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Sci Total Environ. 2021 Nov 30;809:152088. doi: 10.1016/j.scitotenv.2021.152088. Epub 2021 Nov 30.

Experimental safety testing shows that the NSAID tolfenamic acid is not toxic to Gyps vultures in India at concentrations likely to be encountered in cattle carcasses.

The Science of the total environment

S Chandramohan, John W Mallord, Karikalan Mathesh, A K Sharma, K Mahendran, Manickam Kesavan, Reena Gupta, Krishna Chutia, Abhijit Pawde, Nikita V Prakash, P Ravichandran, Debasish Saikia, Rohan Shringarpure, Avinash Timung, Toby H Galligan, Rhys E Green, Vibhu M Prakash

Affiliations

Centre for Wildlife, Indian Veterinary Research Institute, Bareilly, Uttar Pradesh 243122, India.
RSPB Centre for Conservation Science, The Lodge, Sandy, Bedfordshire SG19 2DL, UK. Electronic address: [email protected].
Bombay Natural History Society, Hornbill House, Mumbai 400023, India.
RSPB Centre for Conservation Science, The Lodge, Sandy, Bedfordshire SG19 2DL, UK.
RSPB Centre for Conservation Science, The Lodge, Sandy, Bedfordshire SG19 2DL, UK; Conservation Science Group, Department of Zoology, University of Cambridge, Downing Street, CB2 3EJ, UK.

PMID: 34861305 DOI: 10.1016/j.scitotenv.2021.152088

Abstract

Population declines of Gyps vultures across the Indian subcontinent were caused by unintentional poisoning by the non-steroidal anti-inflammatory drug (NSAID) diclofenac. Subsequently, a number of other NSAIDs have been identified as toxic to vultures, while one, meloxicam, is safe at concentrations likely to be encountered by vultures in the wild. Other vulture-safe drugs need to be identified to reduce the use of those toxic to vultures. We report on safety-testing experiments on the NSAID tolfenamic acid on captive vultures of three Gyps species, all of which are susceptible to diclofenac poisoning. Firstly, we estimated the maximum level of exposure (MLE) of wild vultures and gave this dose to 40 Near Threatened Himalayan Griffons G. himalayensis by oral gavage, with 15 control birds dosed with benzyl alcohol (the carrier solution for tolfenamic acid). Two birds given tolfenamic acid died with elevated uric acid levels and severe visceral gout, while the remainder showed no adverse clinical or biochemical signs. Secondly, four G. himalayensis were fed tissues from water buffaloes which had been treated with double the recommended veterinary dose of tolfenamic acid prior to death and compared to two birds fed uncontaminated tissue; none suffered any clinical effects. Finally, two captive Critically Endangered vultures, one G. bengalensis and one G. indicus, were given the MLE dose by gavage and compared to two control birds; again, none suffered any clinical effects. The death of two G. himalayensis may have been an anomaly due to i) the high dose level used and ii) the high ambient temperatures at the time of the experiment. Tolfenamic acid is likely to be safe to Gyps vultures at concentrations encountered by wild birds and could therefore be promoted as a safe alternative to toxic NSAIDs. It is manufactured in the region, and is increasingly being used to treat livestock.

Keywords: Pharmaceuticals in the environment; Scavengers; South Asia; Uric acid; Veterinary drugs; Vulture-safe

Conflict of interest statement

Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this pa

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Journal Article