The PHurrowed Brow

A valuable drug helps me regain near 20-20 vision. A podcast/radio program reveals that this compound has almost extinguished a critical species of birds because of its overuse in large-animal veterinary medicine. Finally, I see that millions of people in the U.S. benefit from that same medicine in an over-the-counter topical gel. The drug is a thread entwined with several others in strands that stretch from Denver virtually to Delhi, then in real life to the Caribbean and back.

This post is one in a series stretching from Dec. 3rd forward to the 24th.
If the post seems to lack context, I’d encourage you for continuity’s
sake to go back and read earlier ones in order of publication.

III. The Diclofenac Die-Off

It is a truism that most medicinal compounds are toxic. This is true within a species. Consider, for example, BOTOX^® injections, a treatment that I might vainly seek to hide my aging. (I get that I do so need a makeover, and those shots might help.) But the active compound in them would poison me if I ingested it, whether foolishly straight from the vial or incidentally by consuming meat or other foods tainted by the bacterium clostridium botulinum, which is what produces the active ingredient in BOTOX^®. And it is equally true that medical compounds considered safe are highly toxic to other species. The acetaminophen which might ease my soreness after exercise would be highly toxic to my daughter’s cat. Even an empty bottle containing acetaminophen residue can be lethal, as this very sad case study reveals. The truism is always easy to overlook, given the proliferation of helpful compounds which prolong and enhance life. It can be especially easy to overlook when a product’s marketing does such a wonderful job masking the scarier facts of a compound’s origin. People might not unquestioningly sign up (and pay up!) for cosmetic injections of botulinum neurotoxin, which is in fact BOTOX^®’s precursor compound, if it were not trademarked under a less straightforward name. Now the next question I’d really like to ask is why my dentist (???) is so concerned about my crow’s feet and my furrowed brow. My eyes and forehead are not my mouth, and yet she keeps emailing me advice and offers…

This post is one in a series stretching from Dec. 3rd forward to the 24th.
If the post seems to lack context, I’d encourage you for continuity’s
sake to go back and read earlier ones in order of publication.

In my last post I noted a truly significant ecological disaster that was the outcome of cross-species medical toxicity. It involved (and involves) the compound diclofenac sodium. In ophthalmic applications, it is truly valuable for millions of humans, as I have experienced in my own ‘case study.’ And when applied externally in a topical gel, diclofenac sodium is also of considerable benefit to people (more on that later).The liquid form of it is also safely used (by trained vets!) for treatment of ophthalmic conditions in pets. In other veterinary applications, diclofenac sodium is predominantly used (and tremendously valuable) in treating large animals, i.e. animals regularly classed as livestock. Consider this statement on the website of one manufacturer of the injectable compound:

“Diclofenac sodium injection for veterinary use is for the treatment of various bacterial infections in sheep, swine, cattle, goats, and calves. Diclofenac sodium injections are used for hemorrhagic enteritis, diarrhea, typhoid fever, yellow scour of newborn pigs, swine pneumonia, atrophic rhinitis, white diarrhea, fowl cholera, foot rot, dysentery, mastitis, acute septicemia, and chronic respiratory disease.”

In such veterinary applications, diclofenac has been in widespread (and life-saving!) use for decades. The conditions listed above are, if untreated, generally fatal. Diclofenac is a helpful intervention. But in several particular regions and cultural/ agricultural contexts, it has led to disastrous cross-species lethality. How? This lethality is a result of the chemical’s build-up in the bodies of the treated animals which, after death, ended up being consumed by carnivorous and scavenging animals. Birds are particularly at risk of such poisoning.

The story of the diclofenac disaster was set in South Asia, and it was particularly devastating in India. If you listened to the segment of Science Friday which I linked in my previous post, you got a hint of the story. (You may also read the segment transcript, if you so desire.) The story is a complex one. In the 1990s and 2000s, treatment of large animals with injections of diclofenac became increasingly common. Animals so treated eventually died. In many cases, naturally, they died of the conditions for which they were treated. And in such circumstances, they died with relatively large amounts of diclofenac in their tissues, especially their kidneys. Such deceased animals are not fit for human consumption, whether such fitness is adjudged according to scientific, religious, or cultural beliefs. In India, over and above the scientific reasons for eschewing consuming parts of a diseased animal, a cow or goat kept for producing milk that so perished would-be off-limits because of tenets of the faiths to which the majority of Indians adhere: a Hindu will not eat the flesh of bovines: a Muslim will not eat the flesh of an animal that is does not die through halal slaughter. What becomes of the animal?

In large-scale American animal agriculture, dead (unslaughtered) animals are, by regulation, to be segregated for disposal rather than being processed into food. The permitted methods may include rendering into by-products which do not enter the production chain that ends in consumption by humans or pets. But it can take time before a dead animal is found in a pasture. And in India, the standards were different. The natural disposal method, consumption by those without religious scruple or scientific belief (e.g. microbes, invertebrates, reptiles, mammals, and birds) was most common. Of course, such consumers had evolved to play the role of disposer, amongst other important roles in their ecosystems. Some, however, evolved with a high sensitivity to diclofenac and perished because they consumed that compound second-hand.

There are immense cultural prejudices in the west against vultures, griffons, condors, and buzzards. Don’t get me wrong, I’m not for indiscriminately killing American Bald Eagles, but during my childhood it was their plight, not the plight of the equally majestic California Condor which eventually contributed to the banning of the pesticide DDT. In English parlance, being referred to as a buzzard or a vulture, the most common moniker for these carnivorous birds which consume carrion as part of their diets, is almost as dehumanizing as being called a rat, vermin, or parasite. Despite such prejudices, carrion-eating birds play an immensely important role in safely disposing of flesh which would otherwise spawn and spread contagion. They, in my unscientific opinion, feast at the apex of the food pyramid, and preserve the stability of the lower levels of the pyramid at which you, I, and other animals take their repast. Potential outcomes (some of which came to pass in India) include the spread of disease and the disruption of roles that other animals played in the ecosystem. Indeed, the die-off of such important birds due to diclofenac and similar veterinary medicines is of such great importance that it has been the subject of investigative and, one may hope, preventative study not only in Asia, but in Africa, Europe, and the United States. (For a wide-ranging longform treatment of the diclofenac die-off and its cultural contexts from Western culture’s biases against vultures/ griffons/ buzzards to others where vultures are highly regarded, I earnestly recommend Meir Rinde’s article “Poison Pill: The Mysterious Die-Off of India’s Vultures”.) No doubt these studies and the necessary interventions that may result from them, will need to continue.

But closer to home, or indeed in our homes, we may need to be on guard against animal death or illness due to diclofenac toxicity. Why? The relatively recent granting of over-the-counter access to diclofenac, which is also sold under the brand name Voltaren, means that many people are applying the compond to their skin. The prescription use of diclofenac in a topical gel for humans first occurred in 2007 and the compund is indeed beneficial for treatment of arthritis and other causes of inflammatory pain in joints). More recently, in February of 2020, the FDA authorized a formulation of it for over-the-counter sale. Perhaps it was because of the emergent COVID-19 pandemic, plus my preoccupation with the consequences of viral infection and my consequent reduction of time spent in stores, but I did not know that this gel was widely available. Then, too, I am exceedingly fortunate not do suffer from debilitating pain. In any case, it was not until March of 2023 that I ‘discovered’ Voltaren’s/ diclofenac’s existence (but that’s a story for another post). And it was not until I traced this path from my eye surgery in Colorado to massive bird die-off in Asia that I also came to learn the diclofenac is among the many compounds toxic to pets, including dogs and especially cats. Beyond the unlikely scenario of an animal getting into one’s eyedrops or tube of gel, one must consider the possibility of a topical gel on the skin of a pet’s human is licked by the pet. Please don’t misunderstand, I do not mean to be a vector for needless alarm. If your life is enriched by animal companions, you’re probably zealously well-informed and jealously protective of their health. And, I’d think, the odds of such a poisoning happening in any given household are slim.

In my house, such odds are currently zero because my frequent travels make me unfit to be a guardian for pets. (Nevertheless, we are careful when friends bring their pups over.) Sometimes I travel for farm-related purposes. Other trips are purely for adventure. I still have not managed the trip to India that I have long hoped to make, but you can bet that I’ll have my eyes open for vultures and griffons when I do arrive there in real life. In the meantime, I will continue learning about the people, wildlife, and richness of culture there.

Join me in tomorrow’s post where I describe the heroism and horror in a story of India’s black kites, the successor species which has stepped into the void created by the diclofenac vulture die-off, and a small group of people determined to save those kites from a much greater human-caused peril. It’s the compelling story told in Shaunak Sen’s Oscar-nominated documentary, All That Breathes. And it’s a virtual adventure that we all can share. Here’s a preview:

If you enjoy what you’ve read, please post a comment. Likewise, do so if you were troubled by it. Or use the Contact button to send me a private message. And to have you subscribe to the blog at the bottom of the page, well, I should like it of all things!