I’d like to begin this blog by acknowledging how important the drug pentobarbital sodium is as a euthanasia drug in veterinary medicine, shelter population management, and lab animal research. Here in the United States, there is no question it is the most common euthanasia agent used in private veterinary practice and shelter work, and in laboratories it is used when it’s deemed the most efficient method compared to gas inhalation or physical methods. Being a private practitioner myself, I’ve used the drug to euthanize well over 10,000 pets. I trust it to smoothly achieve death in my patients and be irreversible. That’s priceless. But pentobarbital comes with environmental baggage. It’s time for us to take heed and do what we can to use it with greater stewardship.
Where does the pentobarbital risk reside? It’s two fold…scavenger risk and environmental contamination. Pentobarbital is a barbiturate anesthetic drug used to overdose animal patients. The drug remains essentially unmetabolized in the deceased animal’s tissues; the same chemical structure as when it was administered. If ingested from euthanized/deceased animals, the scavenger animal could inadvertently overdose and euthanize themselves. This has been documented in numerous cases and serious enough that veterinarians can receive substantial fines if the scavenger animal is an endangered or threatened species. Danger from ingestion occurs anytime a ‘pentobarbitaled’ body enters the food chain. You may have heard stories of pet food companies finding traces of pentobarbital in their products from meat animals euthanized with the drug. It’s not supposed to happen but it does.
The second risk comes from environmental contamination. Pentobarbital is undesirable in soil and water. While it’s not the only offender that’s generated from vet med drugs, it tends to get the press because it’s designed to kill. Composting has been shown to reduce soil contamination which is good, however most animals don’t get composted. Burial is much more common, especially for companion animals like dogs and cats, the two species almost never euthanized with anything but pentobarbital. Burial is common for exotic pets too, when the cost of cremation may be too high. Companion animal burial has minimal regulations around it, especially as it pertains to pentobarbital.
A few key burial considerations need to be addressed up front
- The burial property – the pet owner either needs to own the property or have clear permission to use another’s.
- Bury deep enough – the optimal depth to bury a deceased pet is between 3 to 5 feet. This allows for microbes to reduce the body while being deep enough to prevent most wildlife from reaching it. Additional cover like stone slabs is beneficial.
- Avoid utilities and tree roots – burying a pet deep means pet owners may encounter buried utility lines. Encourage them to learn what’s in the area before starting. And many love to bury pets under trees. Damage to roots may kill the tree.
- Avoid flood planes – the burial spot should be level or slightly higher than other surrounding areas to avoid pooling water. To the detriment of neighboring communities, water picks up disease and chemicals and may move it downstream.
At a recent talk at the 2023 American Veterinary Medical Association (AVMA) Humane Endings Symposium, speakers highlighted pentobarbital’s use and likelihood that veterinarians adequately explained environmental risk to clients. The results showed that large animal veterinarians were more likely to discuss pentobarbital contamination with clients compared to small animal veterinarians. This may be due to early decisions around body care that large animal veterinarians and owners need to consider. The bigger the animal, the more complicated its handling/removal will be. Large animals such as companion livestock may inadvertently enter the food chain so vets need to be very clear this cannot happen if pentobarbital is on board. In my experience, just like this AVMA talk suggested, small animal veterinarians do not go into great detail about the risks. In my opinion, this is because talking about the death of a companion animal is already highly emotional, and the unpleasant topic of scavenger ingestion may feel overwhelming.
To build something positive from all this, let’s review a statement from a recent AVMA literature review on the matter of pentobarbital use. “The result [of rigorous evaluation of euthanasia] will be a knowledge base that will enable veterinary organizations and regulatory bodies to establish sensible and reasonable recommendations as to how to best handle and administer pentobarbital euthanasia [sticking to doses that make sense], properly dispose of animal remains, prevent contamination of the environment, safeguard wildlife and people’s pets, and, most importantly, maintain the highest level of animal welfare.” From here, I think we can start building some pentobarbital-handling recommendations based on what we already know.
Recommendations to reduce pentobarbital risk in euthanized animals
- Preplan with owners in a way that helps them understand the general concerns. They need a simple to follow action plan.
- Follow minimal-labeled euthanasia technique dosing (more is not always better).
- Place bodies in leak-proof containers that prevent drug contamination into the soil.
- Ensure the animal’s body is properly buried. Visually see it if you can.
- Give proper burial instructions and have the owner confirm in writing that they understand.
- If a veterinarian is concerned about improper body handling including inappropriate burial, choose a non-pentobarbital euthanasia method. E.g., sky burials.
- Encourage aftercare body handling like cremation, aquamation or composting rather than burial.
- Design pentobarbital to denature or become inert once euthanasia is complete.
When it comes to companion animal burial, I like to use a phrase such as, “It’s important that we bury her body deep enough to cover with at least 3 feet of earth. I’ve placed a medicine in her body that is poisonous and dangerous to wildlife and other animals, plus we want to keep her well protected.” I once owned a mobile euthanasia company and home burials were very common. Myself and the other doctors had to talk about burial guidelines to protect ourselves from fines, but we also felt an obligation to make sure our patient was protected, and the earth around it. In the coming months, let’s keep working on becoming a larger voice in the mission towards using pentobarbital more wisely. Keep an eye out for AVMA and CAETA recommendations and let’s do more to inform on pet burial and body handling following pentobarbital use.
References
Otten D.R. Advisory on proper disposal of euthanized animals. J. Am. Vet. Med. Assoc. 2001;219:1677–1678. [PubMed] [Google Scholar]
Krueger B., Krueger K.A. U.S. Fish and Wildlife Fact Sheet: Secondary Pentobarbital Poisoning of Wildlife. [(accessed on 28 February 2018)];2002 Available online: https://www.fws.gov/initiative/protecting-wildlife
O’Rourke K. Euthanized animals can poison wildlife: Veterinarians receive fines. J. Am. Vet. Med. Assoc. 2002;220:146–147. [PubMed] [Google Scholar]
Lochner, Hannah L. et al. “Characteristics and Sodium Pentobarbital Concentrations of Equine Mortality Compost Piles in the Upper Midwest.” Journal of equine veterinary science 114 (2022): 104000–104000. Web.
Payne, J et al. “Quantification of Sodium Pentobarbital Residues from Equine Mortality Compost Piles.” Journal of animal science 93.4 (2015): 1824–1829. Web.
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