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Euthanasia of Animals

By

Cia L. Johnson

, DVM, MS, MSc, American Veterinary Medical Association;


Emily G. Patterson-Kane

, PhD, American Veterinary Medical Association

Last full review/revision Feb 2020 | Content last modified Mar 2020
Topic Resources

Euthanasia is the term used to describe a method of killing that minimizes pain, distress, and anxiety experienced by the animal before loss of consciousness. Techniques used in contexts such as pest control, slaughter, or depopulation may not always meet the criteria of euthanasia due to situational constraints.

Acceptable Techniques

Animal slaughter, depopulation, and humane killing are distinguished from euthanasia, because they are performed for reasons different than sparing an animal from unresolvable painful or distressful conditions. Euthanasia of animals is a common procedure performed by veterinary professionals, and because of the seriousness of the action, it deserves appropriate consideration. Some of the most difficult euthanasia decisions that veterinarians are required to make involve the euthanasia of healthy animals when no other alternative for their care can be identified. A veterinarian must be fully prepared to speak frankly about the animal’s condition and be knowledgeable about all possible alternative care resources when interacting with animal owners, caretakers, and control professionals.

Recognizing the importance of a "good death" in the humane termination of an animal’s life, many countries and professional organizations have developed guidelines and recommendations for animal euthanasia; some are more specific for certain species and environmental settings. Most recommendations emphasize certain factors that personnel performing euthanasia should consider when selecting the best method to use:

  • ability of the method to induce loss of consciousness and death with minimal pain and distress

  • time required to induce loss of consciousness

  • reliability

  • safety of personnel

  • irreversibility

  • compatibility with intended animal use and purpose

  • documented emotional effect on observers or operators

  • compatibility with subsequent evaluation, examination, or use of tissue

  • drug availability and human abuse potential

  • compatibility with species, age, and health status

  • ability to maintain equipment in proper working order

  • safety for predators or scavengers should the animal’s remains be consumed

  • legal requirements

  • environmental impacts of the method or disposition of the animal’s remains

Euthanizing agents cause death by three basic mechanisms: 1) direct depression of neurons necessary for life function, 2) hypoxia, and 3) physical disruption of brain activity. Because loss of consciousness resulting from these mechanisms can occur at different rates, the suitability of a particular agent or method will depend on whether an animal experiences distress before loss of consciousness. Unconsciousness, defined as loss of individual awareness, occurs when the brain’s ability to integrate information is blocked or disrupted.

Table
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Ideally, euthanasia techniques cause rapid loss of consciousness, followed by cardiac or respiratory arrest and death. This may occur very rapidly in a technique, such as gunshot targeting the brain, or more gradually, with a method that first induces unconsciousness, such as anesthetic overdose. If loss of motor or respiratory and cardiac function precedes loss of consciousness, as might be the case if paralytic agents are used, animals may become fearful and experience distress, which is not acceptable.

For a list of acceptable methods and agents for euthanasia of different species of animals, see the accompanying table . The full AVMA Guidelines for Euthanasia 2020 provide information necessary to correctly select and implement these techniques.

The Context of Euthanasia

In most cases, the euthanasia of an animal occurs in a context with:

  • prior communication and decision making

  • planning for the euthanasia

  • staging and conducting the euthanasia

  • disposition of the remains

The emotional attachment between animals and their owners or caretakers requires an additional layer of professional respect and care. Discussing euthanasia openly allows everyone the opportunity to understand that the best interests of the animal, owners, and caretakers have been considered.

Veterinary professionals may have unfavorable experiences concerning the end of life resulting from conflict with clients, moral stress relating to participation and outcomes, internalizing the client’s grief, negative input from others, and lack of mental health support. Important mitigating factors are: 1) supportive practice policies with compassionate leadership, and 2) training in communication and deliberative frameworks. Early intervention for personnel experiencing unresolved stress or mental health problems is imperative. (See also Self-care for Veterinarians Self-care for Veterinarians Dr. Peter Constable of the Veterinary Manual Editorial Board discusses his professional journey as well as various career issues related to veterinarians and veterinary students. Dr. Katherine... read more ).

It is important that euthanasia is provided in a manner that minimizes distress to the animal and considers their natural behavior. A euthanasia approach that can be applied in familiar surroundings may help reduce distress. For animals accustomed to human contact, gentle restraint (preferably in a familiar and safe environment), careful handling, and talking during euthanasia often have a calming effect and may also be effective coping strategies for personnel and animal owners. Sedation and/or anesthesia may help to achieve the best conditions for euthanasia. It must be recognized that sedatives or anesthetics given at this stage that change circulation may delay the onset of the euthanasia agent.

Death must be confirmed before disposal of any animal remains. A combination of criteria is most reliable in confirming death, including:

  • lack of pulse, breathing, corneal reflexes and response to firm toe pinch

  • inability to hear respiratory sounds and heartbeat by use of a stethoscope

  • graying of the mucous membranes

  • rigor mortis

None of these signs alone, except rigor mortis, confirms death. Confirming death may best be accomplished by an adjunctive method (eg, thoracotomy, decapitation) performed after the loss of consciousness. Using an adjunctive method may be especially important when euthanizing ectothermic animals, because their heartbeat and respiration are difficult to assess. Animal remains must be disposed of in a legal manner that does not contaminate food sources or the environment.

Key Points

  • The euthanasia process should minimize or eliminate pain, anxiety, and distress before loss of consciousness.

  • Acceptable euthanasia techniques vary by species, age, and health status of the individual animal.

  • Euthanasia can be distressing for owners and veterinary professionals. This should be managed through open dialogue, compassion, and availability of mental health resources.

  • Death must be confirmed before disposal of any animal remains.

  • Animal remains must be disposed of in a legal manner that does not contaminate food sources or the environment.

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