Dehydration in Our Euthanasia Patients; A big concern?

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This week I helped a sweet cat named Charlie with what I refer to as age related changes plus kidney failure.  Age related changes are those often seen in geriatric patients like loss of senses, muscle loss (sarcopenia), slowing down, appetite fluctuations and arthritis.  Kidney failure often hitches a ride on age related changes so I see it often in cats like Charlie. Dehydration is a hallmark symptom and for his euthanasia, it didn’t change my approach.

There are many other conditions that lead to patient dehydration and veterinarians and technicians know it when they see it; the tell-tale skin tenting, sunken eyes, dry coat, dry mouth/nose, thick saliva, and fluctuations in heart rate and blood pressure. There are different levels of dehydration that result from the type of disease, the patient’s ability to drink, the presence or absence of hydration therapy, and diet.  During dehydrated states, the vessels can be constricted making locating veins difficult.  What we know is that regardless of the reason for dehydration, our goal is to deliver euthanasia solution into the body so it can elicit its effects on the brain. 

Euthanasia solution, in particular pentobarbital sodium, must be given at adequate doses to cease all life functions. It can be administered in particular locations in the body with the goal of rapid absorption to induce unconsciousness then death. The question is “Does dehydration in our patients raise a big concern or are we able to proceed as usual without making adjustments?”   I think the answer lies in which euthanasia technique the practitioner uses, or would prefer to use, and the volume of solution they give. 

For Charlie, dehydration didn’t change my approach because I always use the intrarenal euthanasia method.  Regardless of dehydration or the presence of kidney failure, intrarenal injections are effective as long as the dosing is adequate.(1)  If an intravenous injection was chosen, it’s possible his veins would have been thinner and more challenging to locate. In the face of dehydration with vasoconstriction, the approach would be to clip fur to better visualize the vein and use a small gauge catheter. Another recommendation is to select pre-euthanasia anesthetic drugs over sedatives, and preferably dissociative drugs that maintain stronger blood pressures. Dissociative drugs (e.g., ketamine, tiletamine) induce unconsciousness so if intravenous access proves too challenging in a dehydrated patient, they are set for intraorgan injections. (2) 

Much of the time veterinarians will opt for intraorgan injections in any dehydrated patient making venous blood pressure of lesser consequence. This said, regardless of where the pentobarbital is administered, veterinarians report instances when the heart won’t stop. Dehydration may be negatively affecting the solution’s ability to rapidly travel to the brain. When in doubt, the recommendation is to give more, and sometimes more, and sometimes more until cardiac arrest is achieved.

The takeaway is that while ‘yes’ dehydration may force some alterations to a veterinarian’s preferred euthanasia method, modern euthanasia best practices are already geared toward managing it.  This includes shaving fur and using small gauge catheters if attempting to go IV, providing pre-euthanasia anesthetics, and electing for intraorgan injections right from the start. And again, when in doubt give more euthanasia solution to compensate.

1. Cooney KA, Coates JA, Leach LM, Hrenchir KR, Kogan LR. The use of intrarenal injection of sodium pentobarbital for euthanasia in cats. Am J Vet Res. 2021;83(1):95-99. Published 2021 Nov 10. doi:10.2460/ajvr.21.08.0123
2. Robertson SA. Pharmacologic Methods: An Update on Optimal Presedation and Euthanasia Solution Administration. Vet Clin North Am Small Anim Pract. 2020;50(3):525-543. doi:10.1016/j.cvsm.2019.12.004

(Image is of Charlie with his canine friend, having fun on their family farm)

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Dr. Kathleen Cooney

DVM, CHPV, CPEV, DACAW resident Founder, Senior Director of Education for the Companion Animal Euthanasia Training Academy

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