Pet Euthanasia and Natural Death; Similarities and differences

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Companion animals are likely to leave this world via one of two ways; naturally through the normal progression of physical decline or via euthanasia. Often pet owners make the choice for one over the other and sometimes, as in the case of natural death, the body takes over and does what it needs to do.  We can only control so much when it comes to death. This includes what active death itself looks like.  Death is a process with huge variability but the last breaths look very similar between the two.  Those of us who have witnessed the natural death of an animal have likely recognized similarities to euthanasia, and the Companion Animal Euthanasia Training Academy (CAETA) is here to share insights.  Let’s review.

The moment of death is referred to as a perimortem event (before death is antemortem and after death is postmortem).  Changes that occur in the body reflect a series of body system shutdown wherein tissue oxygenation ceases due to lack of blood flow, and the brain stops all functioning.  During pet euthanasia, this occurs through a cascade of events brought on by the type of drug/solution that’s used.  Euthanasia may occur through an overdose of anesthetic working on the brain or by an agent directly stopping the heart. In rare cases, a physical method is used in companion animals such as gunshot or some other manner of brain disruption leading to instant death.  Regardless of the manner of death, the signs of death remain although some may be more pronounced than others. 

Potential Perimortem Signs of Death; Natural or Euthanasia

  1. Agonal breathing (reflexive)
  2. Apnea (breathing stops)
  3. Opisthotonos stretching (large body stretch)
  4. Bodily fluid release
  5. Lack of reflexes
  6. Myoclonic twitches (muscle fasciculations)
  7. Cardiac arrest (heart stops)
  8. Eyes glazing
  9. Body cooling

While the above list gives signs that can occur in any order, cardiac arrest may be one of the last.  The progression of death independent of a direct heart attack is 1. Unconsciousness, 2. Apnea, 3. Cardiac arrest.  The heart may continue to beat slowly for a few minutes after many of the other signs have started. The heart has been shown to maintain electrical activity for upwards of 45 minutes even though death has been pronounced (1).  

What’s important to keep in mind is that signs of death can be very obvious or more subtle.  The body may take many agonal reflexive breaths or just one. The body may release urine but not stool.  The body may stretch upon death or remain perfectly still.  My approach to describing physical changes to pet owners is to refer to everything as ‘energy releasing’.  It holds truth and seems to resonate.  

Some differences include the euthanasia practitioners ability to control some of the expected physical changes.  For example, the delivery rate of euthanasia solution can either increase patient agonal breathing or diminish it.  The use of pre-euthanasia anesthetic drugs to induce unconsciousness before death my lead to less agonal breathing, reduced immediate urination/defecation, and reduced opisthotonos stretching. Natural death is just that, natural.  There is no way to control signs of death or the physical changes that will occur.  The nervous system and cardiovascular shutdown will follow its own path no matter what we attempt to change.  In fact once agonal breathing begins, it will have to run its course which can take a long time, although some work has been done to minimize it (2).

The environment for a peaceful death remains the same for euthanasia and natural death.  A peaceful setting is ideal and lends itself to decreased stress for the dying and loved ones.  Whatever form death takes, we do well to remain calm.  A natural death can appear alarming to those who’ve never seen it before.  Education is important for the pet owner to understand what’s normal and expected.  The same is true for pet euthanasia.  And after death, postmortem changes will be the same regardless of how the animal died. The Companion Animal Euthanasia Training Academy (CAETA) advocates for veterinary practitioners to continue learning everything they can about death and what to expect, including being open to the natural death experience if that is what pet owners prefer.

  1. https://www.frontiersin.org/articles/10.3389/fcvm.2021.747857/full
  2. https://jme.bmj.com/content/28/3/164

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Dr. Kathleen Cooney

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