Animal euthanasia (
euthanasia
Euthanasia (from : + ) is the practice of intentionally ending life to eliminate pain and suffering.
Different countries have different Legality of euthanasia, euthanasia laws. The British House of Lords Select committee (United Kingdom), se ...
from ; "good death") is the act of killing an animal humanely, most commonly with injectable drugs. Reasons for euthanasia include incurable (and especially painful) conditions or diseases, lack of resources to continue supporting the animal, or laboratory test procedures. Euthanasia methods are designed to cause minimal pain and distress. Euthanasia is distinct from
animal slaughter
Animal slaughter is the killing of animals, usually referring to killing Domestication, domestic livestock. It is estimated that each year, 80 billion land animals are slaughtered for food. Most animals are slaughtered for Human food, food; how ...
and
pest control
Pest control is the regulation or management of a species defined as a pest (organism), pest; such as any animal, plant or fungus that impacts adversely on human activities or environment. The human response depends on the importance of the da ...
.
In domesticated animals, the discussion of animal euthanasia may be substituted with euphemisms, such as "put down" or "put to sleep" to make the wording less harsh.
Methods
The methods of euthanasia can be divided into pharmacological and physical methods. Acceptable pharmacological methods include injected drugs and gases that first depress the central nervous system and then cardiovascular activity. Acceptable physical methods must first cause rapid loss of consciousness by disrupting the
central nervous system
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...
. The most common methods are discussed here, but there are other acceptable methods used in different situations.
Intravenous anesthetic

Upon administration of intravenous anesthetic, unconsciousness,
respiratory then
cardiac arrest
Cardiac arrest (also known as sudden cardiac arrest CA is when the heart suddenly and unexpectedly stops beating. When the heart stops beating, blood cannot properly Circulatory system, circulate around the body and the blood flow to the ...
follow rapidly, usually within 30 seconds.
The two-stage process that some veterinarians use includes a first shot that is a
sedative
A sedative or tranquilliser is a substance that induces sedation by reducing irritability or Psychomotor agitation, excitement. They are central nervous system (CNS) Depressant, depressants and interact with brain activity, causing its decelera ...
to make the animal more comfortable and then a second shot that euthanizes the animal. This allows the owner the chance to say goodbye to a live pet without their emotions stressing the animal. It also greatly mitigates any tendency toward spasm and other involuntary movement which tends to increase the emotional upset that the pet's owner experiences.
For large animals, the volumes of
barbiturates required are considered by some to be impractical, although this is standard practice in the United States. For horses and cattle, other drugs may be available. Some specially formulated combination products are available, such as Somulose (
secobarbital
Secobarbital, sold under the brand name Seconal among others, is a short-acting barbiturate drug originally used for the treatment of insomnia. It was patented by Eli Lilly and Company in 1934 in the United States. It possesses anesthetic, antic ...
/
cinchocaine) and Tributame (
embutramide/
chloroquine/
lidocaine
Lidocaine, also known as lignocaine and sold under the brand name Xylocaine among others, is a local anesthetic of the amino amide type. It is also used to treat ventricular tachycardia and ventricular fibrillation. When used for local anae ...
), which cause 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 these mixtures may display apparent
seizure
A seizure is a sudden, brief disruption of brain activity caused by abnormal, excessive, or synchronous neuronal firing. Depending on the regions of the brain involved, seizures can lead to changes in movement, sensation, behavior, awareness, o ...
activity before death. This may be due to premature cardiac arrest. However, if normal precautions (e.g.,
sedation with
detomidine) are taken, this is rarely a problem. Anecdotal reports that long-term use of
phenylbutazone
Phenylbutazone, often referred to as "bute", is a nonsteroidal anti-inflammatory drug (NSAID) for the short-term treatment of pain and fever in animals.
In the United States and United Kingdom, it is no longer approved for human use (except in t ...
increases the risk of this reaction are unverified.
After the animal has died, it is not uncommon for the body to have posthumous body jerks or a sudden bladder or bowel outburst. This is caused by the muscles of the deceased animal's body relaxing.
Inhalants
Gas anesthetics such as
isoflurane and
sevoflurane
Sevoflurane, sold under the brand name Sevorane, among others, is a sweet-smelling, nonflammable, highly fluorinated methyl isopropyl ether used as an inhalational anaesthetic for induction and maintenance of general anesthesia. After desflu ...
can be
used for euthanasia of very small animals. The animals are placed in
sealed chambers where high levels of anesthetic gas are introduced. Death may also be caused using
carbon dioxide
Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...
once unconsciousness has been achieved by inhaled anesthetic.
Carbon dioxide is often used on its own for euthanasia of wild animals. There are mixed opinions on whether it causes distress when used on its own, with human experiments lending support to the evidence that it can cause distress and equivocal results in non-humans.
In 2013, the American Veterinary Medical Association (AVMA) issued new guidelines for carbon dioxide induction, stating that a flow rate of 10% to 30% volume/min is optimal for the humane euthanasia of small rodents.
[2013 AVMA Guidelines for the Euthanasia of Animals](_blank)
/ref>
Carbon monoxide
Carbon monoxide (chemical formula CO) is a poisonous, flammable gas that is colorless, odorless, tasteless, and slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the si ...
is often used, but some states in the US have banned its use in animal shelters: although carbon monoxide poisoning is not particularly painful, the conditions in the gas chamber are often not humane. Nitrogen
Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...
has been shown to be effective, although some young animals are more resistant to the effects, and it currently is not widely used.
The use of gas chambers is not the most humane form of euthanasia as it can take up to 20 minutes to fully euthanize the animal. If the chambers are not calibrated correctly or the animal is ill, the process is only delayed further which can cause more harm to the animal.
Cervical dislocation
Cervical dislocation
In anatomy, cervical is an adjective that has two meanings:
# of or pertaining to any neck.
# of or pertaining to the female cervix: i.e., the ''neck'' of the uterus.
*Commonly used medical phrases involving the neck are
**cervical collar
**cervic ...
, or displacement (breaking or fracturing) of the neck, is an older and less common method of killing small animals such as mice. When performed properly, it is intended to cause a death that is as painless as possible and has no cost or equipment involved. The handler must know the proper method of executing the movement which will cause the cervical displacement and without proper training and method education there is a risk of not causing death and can cause severe pain and suffering. It is unknown how long an animal remains conscious, or the level of suffering it goes through after a correct snapping of the neck, which is why it has become less common and often substituted with inhalants.
Intracardiac or intraperitoneal injection
When intravenous injection is not possible, euthanasia drugs such as pentobarbital
Pentobarbital (US) or pentobarbitone (British and Australian) is a short-acting barbiturate typically used as a sedative, a preanesthetic, and to control convulsions in emergencies. It can also be used for short-term treatment of insomnia but ...
can be injected directly into a heart chamber or body cavity. With regard to state and federal laws, one of the most humane forms of euthanizing animals is through the injection Sodium Pentobarbital. This is typically the second shot that is followed after a sedative when euthanizing animals.
While intraperitoneal injection is fully acceptable (although it may take up to 15 minutes to take effect in dogs and cats[), an intracardiac (IC) injection may only be performed on an unconscious or deeply sedated animal. Performing IC injections on a fully conscious animal in places with humane laws for animal handling is often a criminal offense.
]
Shooting
This can be a means of euthanasia for large animals—such as horses, cattle, and deer—if performed properly.
This may be performed by means of:
; Firearms
A firearm is any type of gun that uses an explosive charge and is designed to be readily carried and operated by an individual. The term is legally defined further in different countries (see legal definitions).
The first firearms originated ...
: Traditionally used in the field for euthanizing horses, deer or other large game animals. The animal is shot in the forehead with the bullet directed down the spine through the medulla oblongata
The medulla oblongata or simply medulla is a long stem-like structure which makes up the lower part of the brainstem. It is anterior and partially inferior to the cerebellum. It is a cone-shaped neuronal mass responsible for autonomic (involun ...
, resulting in instant death. The risks are minimal if carried out by skilled personnel in a suitable location.
; Captive bolt gun: Commonly used by the meat packing industry
The meat-packing industry (also spelled meatpacking industry or meat packing industry) handles the Slaughter (livestock), slaughtering, Food processing, processing, packaging, and distribution of meat from animals such as cattle, pigs, sheep and o ...
to slaughter cattle and other livestock. The bolt is fired through the forehead causing massive disruption of the cerebral cortex
The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. It is the largest site of Neuron, neural integration in the central nervous system, and plays ...
. In cattle, this stuns the animal, though if left for a prolonged period it will die from cerebral oedema. Death should therefore be rapidly brought about by pithing or exsanguination
Exsanguination is the loss of blood from the circulatory system of a vertebrate, usually leading to death. The word comes from the Latin 'sanguis', meaning blood, and the prefix 'ex-', meaning 'out of'.
Exsanguination has long been used as a met ...
. Horses are killed outright by the captive bolt, making pithing and exsanguination unnecessary.
Reasons
The reasons for euthanasia of pets and other animals include:
* Terminal illness
Terminal illness or end-stage disease is a disease that cannot be cured or adequately treated and is expected to result in the death of the patient. This term is more commonly used for progressive diseases such as cancer, rather than fatal injur ...
, e.g. cancer
Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Po ...
or rabies
Rabies is a viral disease that causes encephalitis in humans and other mammals. It was historically referred to as hydrophobia ("fear of water") because its victims panic when offered liquids to drink. Early symptoms can include fever and abn ...
* Illness or accident that is not terminal but would cause suffering for the animal to live with, or when the owner cannot afford the treatment or has a moral objection to the treatment
* Old age and deterioration leading to loss of major bodily functions, resulting in severe impairment of the quality of life.
* Dementia in pets leading to loss of cognitive function and normal daily behaviour and interactions with owner. Dementia resulting in unsocial and repetitive behaviour causing prolonged stress for both pets and their owners.
* A hunter's coup de grâce
* Behavioural problems (usually ones that cannot be corrected) e.g. aggression
Aggression is behavior aimed at opposing or attacking something or someone. Though often done with the intent to cause harm, some might channel it into creative and practical outlets. It may occur either reactively or without provocation. In h ...
– Canines that have caused grievous bodily harm
Assault occasioning grievous bodily harm (often abbreviated to GBH) is a term used in English criminal law to describe the severest forms of battery. It refers to two offences that are created by sections 18 and 20 of the Offences against the ...
(severe injuries or death) to either humans or other animals through mauling are usually seized and euthanised ('destroyed' in British legal terms)
* Lack of home or caretaker or resources for feeding
* "Convenience euthanasia", if the owner no longer wants to care for the pet
* Research and testing – In the course of scientific research or testing, animals may be euthanized in order to be dissected, to prevent suffering after testing, to prevent the spread of disease, or other reasons[
Small animal euthanasia is typically performed in a veterinary clinic or hospital, at ]animal shelter
An animal shelter or pound is a place where stray, lost, abandoned or surrendered animals – mostly dogs and cats – are housed. The word "pound" has its origins in the animal pounds of the agricultural communities, where stray livestock w ...
, or at the pet owner's home and is usually carried out by a veterinarian
A veterinarian (vet) or veterinary surgeon is a medical professional who practices veterinary medicine. They manage a wide range of health conditions and injuries in non-human animals. Along with this, veterinarians also play a role in animal r ...
or a veterinary technician working under the veterinarian's supervision. Often animal shelter workers are trained to perform euthanasia as well. Knowing when it's time to put a pet down can be difficult. A licensed veterinarian can help an owner determine when in the course of an illness or behavioral problem euthanasia is appropriate.
In the case of large animals which have sustained injuries, this will also occur at the site of the accident, for example, on a racecourse.
Some animal rights
Animal rights is the philosophy according to which many or all Animal consciousness, sentient animals have Moral patienthood, moral worth independent of their Utilitarianism, utility to humans, and that their most basic interests—such as ...
organizations support animal euthanasia in certain circumstances and practice euthanasia at shelters that they operate.
Legal status
In the U.S., for companion animals euthanized in animal shelter
An animal shelter or pound is a place where stray, lost, abandoned or surrendered animals – mostly dogs and cats – are housed. The word "pound" has its origins in the animal pounds of the agricultural communities, where stray livestock w ...
s, most states prescribe intravenous injection as the required method. These laws date to 1990, when Georgia's Humane Euthanasia Act became the first state law to mandate this method. Before that, gas chamber
A gas chamber is an apparatus for killing humans or animals with gas, consisting of a sealed chamber into which a poisonous or asphyxiant gas is introduced. Poisonous agents used include hydrogen cyanide and carbon monoxide.
History
Donatie ...
s and other means were commonly employed. The Georgia law was resisted by the Georgia Commissioner of Agriculture, Tommy Irvin, who was charged with enforcing the act. In March 2007, he was sued by former State Representative Chesley V. Morton, who wrote the law, and subsequently ordered by the court to enforce all provisions of the Act.
Some states allow the use of carbon monoxide chambers for euthanasia.
In the Philippines, the treatment and handling of stray dogs are governed by specific laws that emphasize animal welfare. The primary law is Republic Act No. 8485, also known as the "Animal Welfare Act of 1998," as amended by Republic Act No. 10631 in 2013. This law outlines the responsibilities of local government units (LGUs) and veterinarians in dealing with stray animals.
Remains
Many pet owners choose to have their pets cremated or buried after the pet is euthanized, and there are pet funeral homes that specialize in animal burial or cremation. Otherwise, the animal facility will often freeze the body and subsequently send it to the local landfill.
In some instances, animals euthanized at shelters or animal control agencies have been sent to meat rendering facilities to be processed for use in cosmetics
Cosmetics are substances that are intended for application to the body for cleansing, beautifying, promoting attractiveness, or altering appearance. They are mixtures of chemical compounds derived from either Natural product, natural source ...
, fertilizer
A fertilizer or fertiliser is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from liming materials or other non-nutrient soil amendments. Man ...
, gelatin
Gelatin or gelatine () is a translucent, colorless, flavorless food ingredient, commonly derived from collagen taken from animal body parts. It is brittle when dry and rubbery when moist. It may also be referred to as hydrolyzed collagen, coll ...
, poultry feed, pharmaceuticals
Medication (also called medicament, medicine, pharmaceutical drug, medicinal product, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy ( pharmacotherapy) is an important part of the ...
and pet food
Pet food is animal feed intended for consumption by pets. Typically sold in pet stores and supermarkets, it is usually specific to the type of animal, such as dog food or cat food. Most meat used for animals is a byproduct of the human food indus ...
. It was proposed that the presence of pentobarbital
Pentobarbital (US) or pentobarbitone (British and Australian) is a short-acting barbiturate typically used as a sedative, a preanesthetic, and to control convulsions in emergencies. It can also be used for short-term treatment of insomnia but ...
in dog food may have caused dogs to become less responsive to the drug when being euthanized. However, a 2002 FDA study found no dog or cat DNA in the foods they tested, so it was theorized that the drug found in dog food came from euthanized cattle and horses. Furthermore, the level of the drug found in pet food was safe.
See also
* Animal chaplains
* Animal loss
The loss of a pet or an animal to which one has become emotionally bonded oftentimes results in grief which can be comparable with the death of a human loved one, or even greater, depending on the individual. The death can be felt more intensely ...
* Animal slaughter
Animal slaughter is the killing of animals, usually referring to killing Domestication, domestic livestock. It is estimated that each year, 80 billion land animals are slaughtered for food. Most animals are slaughtered for Human food, food; how ...
* Animal welfare
Animal welfare is the quality of life and overall well-being of animals. Formal standards of animal welfare vary between contexts, but are debated mostly by animal welfare groups, legislators, and academics. Animal welfare science uses measures ...
* British Pet Massacre
* Chick culling
* Dysthanasia (animal)
* Insect euthanasia
* Overpopulation in companion animals
In some countries, there is an Overpopulation (biology), overpopulation of pets such as domestic cat, cats, domestic dog, dogs, and exotic animals. In the United States, six to eight million animals are brought to Animal shelter, shelters each yea ...
* Pet
A pet, or companion animal, is an animal kept primarily for a person's company or entertainment rather than as a working animal, livestock, or a laboratory animal. Popular pets are often considered to have attractive/ cute appearances, inte ...
* Rainbow Bridge (pets)
The Rainbow Bridge is the theme of several works written first in 1959, then in the 1980s and 1990s, that speak of an other-worldly place where pets go upon death, eventually to be reunited with their owners. One is a short story by Edna Clyne-Re ...
References
External links
AVMA Guidelines on Euthanasia
Questions Every Pet Owner Has About Dog Euthanasia But is Afraid to Ask
''Euthanasia of Animals Used for Scientific Purposes''
at The University of Adelaide
The University of Adelaide is a public university, public research university based in Adelaide, South Australia. Established in 1874, it is the third-oldest university in Australia. Its main campus in the Adelaide city centre includes many Sa ...
Putting to Sleep Your Pet Dog Cat or Rabbit at Home.
World Internet News chronicles what happens to abandoned dogs.
Reasons to euthanize your pet at home
National Agricultural Library, United States Department of Agriculture
No Kill Advocacy Center – "no kill" shelter advocacy organization
Recommendations for euthanasia of experimental animals: Part1
Recommendations for euthanasia of experimental animals: Part2
Chesley V. Morton v. Georgia Department of Agriculture and Tommy Irvin in his Official Capacity as Commissioner
Is It Time Checklist
{{Death
Animal euthanasia