Definition:

A gentle death that is regarded as a act of humane killing with the minimum of pain, fear and distress.

Objectives:

• Painless 
• Unconsciousness and death are achieved rapidly 
• Minimal restraint and psychological stress 
• Simple, reliable, reproducible and irreversible
• Safe for the operator

Clinical Endpoints:

"In experiments involving animals, any actual or potential pain, distress or discomfort should be minimized or alleviated by choosing the earliest endpoint that is compatible with scientific objectives of the research. " 
- CCAC, 1998 

Experimental Endpoints:
The experimental endpoint, is the estimated survival time for the animals. 
 

Reasons for Euthanasia:

 
Humane endpoint:
• Levels of pain, distress and suffering exceed acceptable limits
• Specific guidelines for physiological parameters (weight loss, reduced mobility, alterations in core body temperature etc) 
• Specific guidelines for certain areas of research (neoplasia, toxicology)


Experimental endpoint: 

• Experimental objectives / results are achieved
• Tissue harvesting
• No longer suitable for breeding
• Unwanted genotype / phenotype 
• Questionable / undesirable health status 

Recognition and Confirmation of Death:

• Cessation of heartbeat and respiration
• Absence of all reflexes
• Central, fixed dilated pupil  (easier to detect in larger species)
• Chemical and physical methods

Acceptable Methods of Euthanasia:

• Species dependent
• Methods differ for anaesthetized vs. unanaesthetized animals
• Physical methods must cause immediate loss of consciousness through physical trauma to the brain

Recommended Methods of Euthanasia:
What best describes a good method of euthanasia is that it consistently produces a humane death.

• For chemical euthanasia, the intravenous route is always preferable to intraperitoneal route due to rapid induction and a quick, humane death. 
• For physical euthanasia, prior anaesthesia is mandatory. If there is no anaesthesia administered prior to a physical means of euthanasia, scientific justification must be provided, with subsequent approval by the local Animal Care Committee.

 Recommended Methods of Euthanasia (by species):
 

FISH: 

Chemical methods 
• Tricaine methane sulfonate (MS 222) immersion overdose. Neutralized to pH 7.5 with bicarbonate 
• Benzocaine immersion overdose. Neutralized to pH 7.5 with bicarbonate 

Physical methods 
• Concussion followed by exsanguination, removal of the heart or cervical dislocation

Anaesthetized fish: 
• Pithing
• Decapitation
• Exsanguination

AMPHIBIANS:

Chemical methods 
• MS 222 immersion overdose. Neutralized to pH 7.5 with bicarbonate 
• Benzocaine immersion overdose. Neutralized to pH 7.5 with bicarbonate
• Sodium pentobarbital overdose (intravenous, IV or intraperitoneal, IP)
Physical methods 
• Concussion followed by pithing
• Decapitation and pithing 
Anaesthetized amphibians 
• Pithing

REPTILES:

Chemical methods 
• Sodium pentobarbital overdose (IV or IP)
Physical methods 
• Captive bolt followed by destruction of brain
Anaesthetized reptiles: 
• Pithing
• Decapitation
Note: For amphibian and reptilian species, inhalational anaesthetics are an unacceptable means of euthanasia due to breath holding capacity, resulting in prolonged induction times. 

BIRDS:

Chemical methods 
• CO2 (in chicks up to 72 hours old)
• Volatile inhalational anaesthetic overdose
• Sodium pentobarbital overdose (IV or IP)
Physical methods 
• Concussion followed by exsanguination or decapitation
• Anaesthetized birds:
• Decapitation
• Pithing
• Potassium chloride
Note: exsanguination is unacceptable in birds due to rapid blood clotting 

RODENTS:

Chemical methods 
• Sodium pentobarbital overdose (IV or IP)
• Inhalation anaesthetic overdose
• CO2 (animals more than 10 days old)
Physical methods 
• Microwave irradiation in specially designed units
Anaesthetized rodents 
• Cervical dislocation
• Decapitation
• Rapid freezing
• Exsanguination

Chemical methods 
• Sodium pentobarbital overdose (IV or IP)
• Inhalation anaesthetic overdose – prior sedation mandatory 
Anaesthetized rabbits 
• Exsanguination
• Potassium chloride

CARNIVORES: Dogs, cats, ferrets

Chemical methods 
• Sodium pentobarbital overdose (IV only) – prior sedation mandatory 
• Inhalational anaesthetic overdose – prior sedation mandatory
Physical methods (field conditions only) 
• Shooting
Anaesthetized carnivores 
• Exsanguination
• Potassium chloride

LARGE MAMMALS (Pigs, sheep, goats, cattle)

Chemical methods 
• Sodium pentobarbital overdose (IV only) – prior sedation mandatory 
• Inhalation anaesthetic overdose (lambs and kids only) – prior sedation mandatory 
Physical methods (field conditions only) 
• Captive bolt followed by exsanguination
• Free bullet humane killers
• Shooting
Anaesthetized large mammals 
• Exsanguination
• Potassium chloride

NON-HUMAN PRIMATES

Chemical methods 
• Sodium pentobarbital overdose (IV only) – prior sedation mandatory 

Unacceptable Methods of Euthanasia for All Species:

• Air embolism
• Burning (chemical or thermal)
• Carbon monoxide 
• Chloral hydrate
• Chloroform
• Cyanide
• Decompression / vacuum
• Drowning
• Diethyl ether
• Exsanguination without anaesthesia
• Formalin
• Household products and solvents
• Hypothermia / hyperthermia
• Ketamine
• Magnesium sulfate
• Methoxyflurane
• Narcotics
• Neuromuscular blocking agents
• Nitrous oxide
• Rapid freezing without anaesthesia
• Removal from water (gilled vertebrates)
• Strangulation
• Strychnine