My watch list

Animal euthanasia

Additional recommended knowledge

Correct Test Weight Handling Guide: 12 Practical Tips

How to ensure accurate weighing results every day?

Guide to balance cleaning: 8 simple steps

1 Methods
2 Reasons for euthanasia
3 Animal shelters
4 References
5 See also

In falconry, "putting a hawk down" may mean putting it in the mews for its moult.

Animal euthanasia (Greek, "good death") is the act of inducing humane death in an animal.^[1] Euthanasia methods are designed to cause minimal pain and distress.

In pet animals, this process is commonly referred to by the euphemisms "put to sleep" or "put down".

Methods

Intravenous anesthetic

Pets are almost always euthanized via intravenous injection, typically a very high dose of a barbiturate such as pentobarbital. Unconsciousness, respiratory then cardiac arrest follow rapidly, usually within 30 seconds^[2]. Observers generally describe it as a quick and peaceful death.

Some veterinarians perform a two-stage process: An initial injection that simply renders the pet unconscious and a second shot that induces death. This allows the owner the chance to say goodbye to a live pet without their emotions stressing the pet.

For large animals,the volumes of barbiturates required are frequently impractical. In such cases, shooting (see below) may be more appropriate. Alternatively, for horses and cattle, other drugs may be available. In some countries (e.g. the UK) a cocktail of Secobarbital (a high-potency barbiturate) and Cinchocaine is available, providing deep unconsciousness and cardiac arrest independently, with a lower volume of injection, thus making the process faster, safer and more effective. Occasionally a horse injected with this mixture displays apparent seizure activity prior to death, this may be due to premature cardiac arrest. However, if normal precautions (e.g. sedation with detomidine) are taken, this is a rare problem^[3]. Anecdotal reports that long term use of phenylbutazone increase the risk of this reaction are unverified.

Inhalant (gas) anesthetic

Gas anesthetics such as isoflurane and sevoflurane can be used for euthanasia in very small animals (rodents, small birds, etc.). Animals are placed in sealed chambers where high levels of anesthetic gas are introduced. Death may also be induced by carbon dioxide once unconsciousness has been achieved by inhaled anaesthetic^[4].

Intracardiac or intraperitoneal injection

When intravenous injection is not possible, euthanasia drugs such as pentobarbital can be injected directly into a heart chamber or body cavity.

While intraperitoneal injection is fully acceptable (although it may take up to 15 minutes in dogs and cats^[4]), an intracardiac (IC) injection may only be performed on an unconscious or deeply sedated animal. In California, IC injection on a fully conscious animal is a crime [Calif. Penal Code 597u (a)(2)].

Shooting

Often the most appropriate means of euthanasia for large animals (e.g. horses, cattle). This may be by means of:

1) Free bullet. Traditionally used for shooting horses. The horse is shot in the forehead, with the bullet directed down the spine through the medulla oblongata, resulting in instant death^[5]. The risks are minimal if carried out by skilled personnel in a suitable location.

2) Captive bolt. Commonly used for cattle etc. The bolt is again fired through the forehead causing massive disruption of the cerebral cortex. In cattle this merely stuns the animal, and death must be brought about by pithing or exsanguination (cattle have been reported to make complete recoveries after being stunned. Horses are killed outright by the captive bolt, making pithing or exsangination unnecessary^[6]).

Reasons for euthanasia

Terminal illness - e.g. cancer
Behavioral problems - e.g. aggression
Stray and feral animal overpopulation - not enough adoptive homes
Illness or broken limbs that would cause suffering for the animal to live with, or when the owner has insufficient financial reserves to pay for (or a moral objection to) treatment.
Old Age - Deterioration to loss of major bodily functions. Severe impairment of the quality of life.

Small animal euthanasia is typically performed in a veterinary clinic or hospital, or in an animal shelter, and is usually carried out by a veterinarian, or a veterinary technician working under the vet's supervision. Often animal shelter workers are trained to do euthanasia as well. Some veterinarians will perform the euthanasia at the pet owner's home - this is virtually mandatory in the case of large animal euthanasia; except in the case of horse racing, where the injured animal is sometimes put down on the track.

Animal shelters

Main articles: Animal shelter and no-kill shelter

According to the American Humane Association, an estimated 9.6 million animals are euthanized in the United States every year. The majority of these are euthanized at animal shelters, typically after a standard period of time (ranging from several days to several weeks for unclaimed stray animals).

"No kill" shelters exist, some run by private animal welfare organizations, while others are subsidized wholly or in part by local government agencies or private donations. These shelters make it official policy never to euthanize animals for non-medical reasons

References

^ 2000 Report of the AVMA Panel on Euthanasia
^ UK Veterinary Medicines Directorate Product Notes for 20% Pentobarbital solution. [1]
^ NOAH Compendium of Data Sheets for Animal Medicines 2005
^ ^a ^b Laboratory Animal Euthanasia (DOC). Australian National University. Retrieved on 2007-11-30.
^ Tom J. Doherty, Alex Valverde, Manual of Equine Anaesthesia and Analgesia, Blackwell Publishing 2006 (p. 352)
^ C.J. Laurence, "Animal welfare concequences in England and Wales of the 2001 epidemic of foot and mouth disease", Rev. sci. tech. Off. int. Epiz, 2002, 21 (3), 863-868)