The use of the anti-inflammatory drug Diclofenac on cattle led – very indirectly – to the rise of rabies and leopards in India. And it’s all because of vultures.
Sometimes the natural world makes it abundantly clear that we mess with it at our own peril. One such example is the Indian vulture crisis: a weird chain of events that began with a livestock drug and ended with a big uptick in rabies cases.
Diclofenac is a drug commonly used to treat fever and inflammation. You might have heard of it under the brand name Voltaren. Beginning in the 1990s, vets in India used Diclofenac to treat sick livestock. This drug is very effective for cattle, but it turned out that it wasn’t so great for all animals.
Vultures who ate carcasses of Diclofenac-treated cattle died. And because vultures were the natural disposal method for cattle in India, a lot of vultures died. The total population of vultures in India crashed: the white-rumped vulture, for example, went from the most common large bird of prey in the world (several million strong) to a spot on the critically endangered list – less than 10,000 remain worldwide.
Nature’s woes didn’t end there. In India the vultures served a very important body disposal function, both of cattle carcasses and sometimes of humans (see, for example, the Zoroastrian Tower of Silence). In the absence of vultures, wild dogs took over cattle-disposal, and the dog population soared.
The sudden rise of wild dogs led to a huge increase in rabies cases in India, and then the leopards began moving into populated areas to hunt the wild dogs. And all of this from the introduction of one veterinary drug.
(Diclofenac was banned in India in 2006, and work continues to rehabilitate the vulture population and restore some kind of balance.)
[Thanks to Siobhan L. for suggesting this topic.]