|Year : 2018 | Volume
| Issue : 1 | Page : 30
Medical News – From around the world
|Date of Web Publication||27-Apr-2018|
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
. Medical News – From around the world. Curr Med Issues 2018;16:30
When animals become accidental victims
In the mid-1990s biologists began noting rapid declines in vulture populations in India. Cities that had hosted thousands of birds were suddenly vulture-free. Something was killing massive numbers of vultures, but what? Diverse explanations abounded. Years later, a research team convicted the commonly used analgesic diclofenac sodium of preying umpteen vultures in Asia. They figured out that a miniscule amount of diclofenac could cause severe kidney damage in vultures of the genus Gyps, commonly known as griffon vultures.
Diclofenac became widely available across India as a cheap veterinary drug in the early 1990s to treat inflammation, fever and pain in cattle.
Diclofenac causes severe acute tubular necrosis in vultures resulting in rapid precipitation of urates within the tubule lumen as the epithelium of the proximal convoluted tubules dies. Experimental vultures showed a short duration of illness and rapid lesion progression to death after diclofenac exposure.
The Indian subcontinent began banning diclofenac in 2006 for veterinary use and since then, vulture populations in the region seem to have halted their precipitous declines.
There are many such drugs which are relatively safe and commonly used by humans when accidentally exposed to animals or birds can pose threat to their lives.
In the majority of animals and humans, paracetamol toxicity primarily causes damage to the liver. However, while cats can and do have liver damage with paracetamol, the primary manifestation of toxicosis is severe methemoglobinemia leading to hemolysis and methemoglobinuria.
Paracetamol primarily undergoes hepatic metabolism to sulphate and glucuronide conjugates (50-60%), while a small amount (<3%) is metabolized by CYP2E1 to a highly reactive intermediate, N-acetyl-p-benzoquinone imine (NAPQI), which is conjugated rapidly with glutathione and inactivated to nontoxic cysteine and mercapturic acid conjugates. Cats are relatively deficient in activity of the enzyme glucuronyl transferase which conjugates paracetamol to glucuronic acid for excretion. Therefore, in cats a relatively greater proportion of paracetamol is available and metabolized to reactive intermediate compounds. Cellular stores of glutathione become rapidly depleted in the liver, erythrocytes, as well as in other cells throughout the body, leaving the cells unprotected from the oxidizing effect of the toxic metabolite NAPQI. One low dose paracetamol (325mg) may be toxic to cats, and a second could be lethal.
In 1999, a veterinarian and a rancher in Colorado were dismayed to find that they had accidentally killed five golden eagles and two bald eagles. The birds died after feeding on two mule carcasses that had been euthanatized with phenobarbitone. The drug can be poisonous to animals and birds and remains potent in a carcass long after an animal dies. Similar incidents have been reported in dogs too.
In April 2015, the US FDA alerted pet owners and others that using topical medications containing flurbiprofen (an NSAID) on themselves for muscle, joint or other pain could be dangerous to pets when exposed even in very small amounts. The alert is based on reports of cats in two households that became ill and subsequently died after their owners used topical medications containing flurbiprofen. The pet owners had applied the cream or lotion to their own neck or feet, and not directly to the pet.
The above are only a handful of several such reports available over internet, medical and veterinary literature. There exist immense differences in drug metabolism between species that results in species differences in PK and PD. Drug effect in a given species is beyond predictions, unless it is tested in the lab.
Next time when you buy medicines, store it out of reach of not only children but pets too, otherwise you may need to answer Blue Cross if your medicines injure pets.
| References|| |
Adam Welz. Bird-killing vet drug alarms European conservationists. The Guardian; 11 Mar 2014.
Meteyer CU, Rideout BA, Gilbert M, Shivaprasad HL, Oaks JL. Pathology and proposed pathophysiology of diclofenac poisoning in free-living and experimentally exposed oriental white-backed vultures. J Wildl Dis. 41(4), 2005, pp 707-716.
Acetaminophen (paracetamol): Drug Information. UpToDate [online, 10 Jan 2018].
Tylenol (acetaminophen) toxicosis in cats. Spring 1998 Newsletter. Indiana Animal Disease Diagnostic Laboratory.
Euthanatized animals can poison wildlife: Veterinarians receive fines. JAVMA News; Jan 15, 2002.
Bischoff K, Jaeger R, Ebel JG. An Unusual Case of Relay Pentobarbital Toxicosis in a Dog. Journal of Medical Toxicology. 2011;7(3):236-239.
FDA alert-illnesses and deaths in pets exposed to prescription topical pain medication [online, 17 April 2015].