In India only 4% of the resident 500 million cows are destined to be consumed by humans as India’s major religion, Hinduism, holds cows sacred. Instead, when a cow dies it is left to be eaten by vultures. Vultures in India are thus dependent on human activity and play a massive role in the ecosystem. Vultures are India’s most efficient scavengers and their metabolism acts as an “endpoint” for pathogens, while in the other predominant scavengers in India, like dogs and rats, pathogens can survive and the animal can become a carrier for diseases such as plague, rabies and anthrax.
In the 1990s conservation groups noticed a drop in the vulture populations of India’s National Parks. Between 1993 and 2002 the White-rumped Vulture population decreased to 0.3% of its original size and two other species were in dire threat of extinction. As a result the carcasses that would have previously been eaten by vultures were left to rot, leading to contaminated water and an abundance of disease carrying scavengers, creating a public health crisis.
Parsi, an important religious group in India, believe that when vultures consume a body it liberates the soul and have disposed of their dead in this manner since before 500 BC. However the recent decline in vultures has meant that this practice has had to be abandoned as the bodies rot before they are consumed.
A team of researchers found that an anti-inflammatory drug, diclofenac, which was given to cattle, caused this significant decline in the vulture population. Diclofenac caused renal failure in the vultures, as they do not have the particular enzyme needed to break down diclofenac. Simulations showed that if 1% of cattle had diclofenac in their system when they died, then the Indian vulture population would be decimated. A study of cattle carcasses found that 10% of them contained diclofenac. In India, Nepal and Pakistan diclofenac is now banned for veterinary use and has been replaced with meloxicam. Meloxicam is decreasing in price, but is still more expensive that diclofenac, which has caused a black market for diclofenac, where diclofenac intended for humans is instead used to treat cattle.
In 2013, despite the findings of the scientific community, Spain, home to 90% of Europe’s vulture population, approved diclofenac for veterinary use, and it continues to be used to treat livestock there. This is yet another case where veterinary pharmaceuticals are used to maximise short-term profit, with little regard to the long-term and far-reaching effects.