Back in the spring of 2010, two dogs—a 13-year-old spayed female lab mix and a seven-year-old neutered male Australian Shepherd mix—roamed the pasture near their home in a rural, remote area. The frost was beginning to melt, and the bustle of a new season was on the horizon. A few hours after heading out, the dogs return home, abnormally tired.
According to the owner, both canines were reportedly healthy and alert when they were let out at 8 a.m. When they came back around 10:30 a.m., the female was, as mentioned, ‘tired,’ and went to her bed immediately. She became ‘sleepier and sleepier,’ according to her owner, and, by the afternoon, had lost her palpebral and pupillary reflexes.
Likewise, the male spent the rest of the day sleeping on the couch. When the dog got up in the evening, he was ataxic. This got worse over time. The owner reported his dog soon became confused, apprehensive, and, eventually, hyporesponsive.
At this point—around 9 p.m.—the dogs were loaded into the car for the hour-and-a-half drive to the veterinary hospital. During the trip, the female died.
Post-mortem exam of the dog was unremarkable, save for a stomach full of raw meat and what appeared to be horsehair. Chemical analysis of urine samples of both canines revealed pentobarbital.1 Supportive treatment was given to the male, including warming, IV fluids, and gavage with activated charcoal. He recovered the following morning.
Upon learning his dog’s death was the result of pentobarbital poisoning, the owner decided to retrace the steps his animals likely took the day they became sick. He came upon a horse carcass partially buried in a ravine, located on a neighbour’s property about 300 metres away. The carcass had been scavenged, and the colour of the hair matched the stomach contents of his dog.
The horse’s owner said the animal had been euthanized more than two years earlier. He went on to say his own dog had “laid down and died” shortly after the horse was euthanized and buried. Not long after, the man’s second dog exhibited symptoms similar to those of his neighbour’s dog. He soon, too, died, and was buried next to the horse the following year. This brings the total to three dog deaths related to pentobarbital poisoning.
While this case was not a controlled study, it demonstrates pentobarbital can last undecayed for years in tissues of animals. Further, pentobarbital relay toxicity has been reported in several species as the result of scavenging the remains of animals that had been euthanized with the drug. Finally, some veterinarians have been fined for accidentally poisoning of wildlife due to euthanized carcasses and inadequate burial.
As stewards of animal health, it obliges veterinary professionals to review what has been published regarding environmental persistence in animals euthanized with pentobarbital and review the steps we can take to protect ourselves, our wildlife and companion animals, and the environment.
In recent years, much has been published to educate veterinary professionals on the danger of improper burial of animals euthanized with pentobarbital. Indeed, environmental protection organizations warn the inadequate disposal of our animals can seriously injure or kill many different types of wildlife. What’s more, veterinarians, in many cases, are liable for penalties.
Case in point: in 1999, a veterinarian and a rancher in Colorado were devastated to learn they had accidentally killed five golden eagles and two bald eagles. The raptors died after feeding on mule carcasses that had been euthanized with pentobarbital. Ultimately, the individuals were fined US$10,000 each for involuntarily killing the seven birds.2
These are not the only reported deaths related to this poisoning. In 2003, a medical examiner for the U.S. Fish and Wildlife Service in Oregon noted 17 eagles had died from pentobarbital over a 10-year period. Likewise, a wildlife disease specialist in Wisconsin says from 1986 to 2001, the deaths of 34 eagles were the result of secondary pentobarbital poisoning. Finally, in British Columbia, there are reports of 26 bald eagles becoming ill and five dying after eating a single euthanized cow.2
If an animal dies from secondary toxicity and is part of a welfare or protection act (such as the Eagle Protection Act or Endangered Species Act), the associated fines for responsible parties can be quite high. The penalty for killing a bald eagle, for example, can run as high as US$100,000 for an individual and US$200,000 for an organization.2
Sadly, in many cases, these deaths are linked to the accidental improper burial of a euthanized animal. Indeed, in many reported cases, the incidents involve carcasses people had made a “good faith effort” to discard properly, according to Kathryn Converse, PhD, a wildlife disease specialist at the National Wildlife Health Center (NWHC) in Madison, Wisc. This is why it is imperative to check local guidelines for burial requirements when disposing of a euthanized animal.3
“Many of these [are] associated with landfills, involving pets and domestic animals that had been euthanatized and had not been covered following disposal in a landfill,” Dr. Converse says.2
A lasting effect
The disposal of an animal’s body is a reality for all veterinarians. The inability for this to be carried forth correctly in terms of a proper burial or cremation can have serious consequences in the form of fines and professional liabilities, as demonstrated above.
When it comes to understanding the proper disposal of euthanized animals, it is helpful to be cognizant of how long, exactly, pentobarbital lasts and lingers in carcasses and in the environment—which, according to a 2015 study, can be well over a year.
“Data illustrate sodium pentobarbital was detectable up to 367 days in compost piles with no clear trend of concentration reduction” reports Payne et al.4
Compounding this, the environmental impact can be drastic. Indeed, in a 2017 study, researchers measured degradation of pentobarbital in sand, topsoil, and potting soil over a 17-week period. They found “…as tissues decompose, pentobarbital may leach into the soil and from there migrate to groundwater.” Further, “there were still detectable amounts of pentobarbital present in the soil after 17 weeks.”5
Education is key
To help prevent the tragic incidents detailed above, it is imperative veterinary professionals understand the rules regarding euthanasia and burial service as dictated by their provincial body.6 (The Canadian Veterinary Medical Association [CVMA] refers to the American Veterinary Medical Association [AVMA] aftercare policy for best practices.)
Namely, avoid the use of plastic bags for body disposal, as these have proven to be ineffective for burial and offer no protection to the environment. Resources are available online with best practices for the burial of production animals on a farm, as well as tips for laying companion animals to rest and ensuring the safety of other animals and the surrounding environment.7
To minimize risk, it is also important veterinary professionals share this information with pet owners to ensure they are aware of provincial laws, as well as the risk improper burial poses for other animals and wildlife.
Animal remains containing pentobarbital are potentially poisonous for wildlife or domestic animals, and the use of pentobarbital invokes legal responsibilities for veterinarians, animal shelters, and pet parents. As detailed in this article, pentobarbital can exist in tissue for years after euthanasia. We must ensure the proper disposal of remains. This helps to prevent secondary toxicosis and unnecessary accidents for wildlife and the environment, and also protects veterinarians and animal lovers alike.
Alexandra Yaksich, BSc., AHT, wears many hats. She is currently working as a freelance writer, communications consultant, content creator, and relief animal health technician. Follow her on Instagram (@alexandra.yaksich) or connect with her via LinkedIn.
1 Kaiser A, McFarland W, Siemion R, and Raisbeck M. Secondary Pentobarbital Poisoning in Two Dogs: A Cautionary Tale. Journal of Veterinary Diagnostic Investigation. 2010. https://journals.sagepub.com/doi/10.1177/104063871002200423
2 O’Rourke, K. Euthanatized animals can poison wildlife: Veterinarians receive fines. JAVMA. 2002. https://www.avma.org/javma-news/2002-01-15/euthanatized-animals-can-poison-wildlife-veterinarians-receive-fines
3 For more, see https://www.euthabag.com/handouts
4 Payne J, Farris R, Parker G, Bonhotal J, and Schwarz M. Quantification of sodium pentobarbital residues from equine mortality compost piles. J Anim Sci. 2015. https://pubmed.ncbi.nlm.nih.gov/26020203
5 Bagsby C, Saha A, Goodin G, Siddiqi S, Farone M, Farone A, and Kline P. Stability of pentobarbital in soil. Journal of Environmental Science and Health. 2018. https://www.tandfonline.com/doi/abs/10.1080/03601234.2017.1406714
6 For a complete list of Canada’s regulatory veterinary bodies, see https://www.canadianveterinarians.net/public-resources/regulatory-bodies
7 For more, see https://www.euthabag.com/articles-for-veterinary-team-members