In the coming days, a group of authors including myself are about to finally submit an academic paper on intrarenal euthanasia injections in cats. This study, first started in 2011, looks at the reliability of this technique in felines and the methodology to carry it out. What we found when following the American Veterinary Medical Association (AVMA) 2020 Euthanasia Guidelines dosing recommendations of at least 3 mls per 10 pounds of body weight (based in part on the early results of this study) is that the cats passed in less than one minute. The combination of properly placed injections and adequate volume of euthanasia solution, 3 times the normal intravenous dose, proved to be a highly effective way to achieve rapid death. Most cats have a body weight at or below 10 pounds making 3 mls of euthanasia solution a normal amount to administer. To freshen the study up before submission, the Companion Animal Euthanasia Training Academy (CAETA) took a closer look at today’s trends in intrarenal injections, namely how much euthanasia solution was the average veterinary practitioner administering in cats, and the results were surprising.

In an effort to identify the latest norm in intrarenal injections, we looked at how often veterinary professionals were using the technique and at what dose they were finding success. Again, the AVMA indicates 3 mls per 10 pound (4.5 kg) of body weight as the appropriate dose to achieve rapid and irreversible death in animals. We surveyed 2,159 veterinarians through the Veterinary Information Network (VIN) and here is what we found. Source: VIN Quick Poll.

What is your pentobarbital dosing protocol for intrarenal euthanasia?
1 ml per 4.5 kg (10 pounds) bodyweight (21%)
2 ml per 4.5 kg (10 pounds) bodyweight (11%)
3 ml per 4.5 kg (10 pounds) bodyweight (4%)
< 3 ml per 4.5 kg (10 pounds) bodyweight (1%)
It depends on the species (1%)
I tend to just guess the volume (2.5%)
I use the same volume for most/all intrarenal euthanasias (1%)
I never perform intrarenal euthanasia (57%)
I don’t perform euthanasia at all (<1%)
This does not apply to my job situation (1%)
Other (<1%)

The first data point worth noting is that 32% of respondents dose less than the recommended AVMA amount. Guesses on why this is include a lack of understanding of the AVMA Euthanasia Guidelines or the fact that 1 ml per 10 pound is proving adequate to consistently achieve death. This has not been formally studied and CAETA is not recommending this lower dose. It’s simply an observation. Only 4% are following the recommended dose, while a mere 1% go even higher. A dose of 1 ml per 10 pounds is indicated for intravenous or intracardiac injections, according to the AVMA, CAETA, and pentobarbital manufacturers. If it is an adequate volume for intrarenal injections, more research is needed to substantiate it and protect patient welfare. The second point of interest is that of the 2,159 veterinarians surveyed, almost 60% report not performing the technique at all, opting for other methods like intravenous injections, which proved most popular in a small informal study on intraorgan injections in general.

Our study from 2011 actually used double the AVMA’s recommended dose, as was standard practice for the veterinary service I used to own, Home to Heaven. We liked the extra solution to give until visual active signs of death were seen and ensure we could palpate the renal swelling (expansion of the renal tissue and capsule due to the addition of fluid) that is so indicative of success. This being said, we regularly felt quick swelling, with less than 6 mls of solution administered. We cannot say for sure that euthanasia would have been successful with 1 ml per 10 pound, but it was enough for us to appreciate swelling, and often our patients passed well before 6 mls was given.

For now, we remain certain that intrarenal injections in cats, and all species where the kidney can be isolated, is a viable method of euthanasia at a dose of 3 mls per 10 pound or higher. Perhaps less is needed after all, but more research will guide us. With more and more professionals utilizing the technique, it’s important groups like the Companion Animal Euthanasia Training Academy and AVMA identify the right euthanasia solution dosing sooner than later.

2020 AVMA Guidelines for the Euthanasia of Animals. https://www.avma.org/sites/default/files/2020-01/2020-Euthanasia-Final-1-17-20.pdf
Anon. VIN – Quick Poll. VIN.com 2014. Available at: https://www.vin.com/doc/?id=6267262.