RAR Home

RAR Home


Link to U of M homepageLink to the U of M homepage
Topic Index
IACUC Animal Care Veterinary Care Experiment Guidelines Surgery
Anesthesia
[Euthanasia] Safety Training

Criteria

Acceptable methods

Common Standard

methods

Carbon dioxide chamber

Euthanasia requests

Rodents for Raptors program

Rodent neonate/fetus euthanasia

Wildlife euthanasia pg. 249 (pg 15 of pdf)

 


 

Copyright 2009 University of Minnesota Board of Regents.

The University of Minnesota is an equal opportunity educator and employer.

Euthanasia Guidelines

Animals are normally euthanized at the end of a study for the purpose of sample collection or post-mortem examination.  Animals may be euthanized because they are experiencing pain or distress.  Euthanasia is defined as a pain-free or stress-free death. The IACUC has approved certain methods for humanely killing animals that meet the definition of euthanasia.  The appropriateness of the method may vary from species to species. These guidelines are adapted from the report of the American Veterinary Medical Association Panel on Euthanasia, J Am Vet Med Assoc 2013.  The American College of Laboratory Medicine has issued a report on rodent euthanasia that has many useful references and guidelines.

Euthanizing animals can be psychologically difficult for some personnel, particularly if they perform euthanasia repetitively or are emotionally attached to the animals being euthanized. When delegating euthanasia responsibilities, supervisors should be sensitive to this issue. Investigators or technicians who require advice or assistance on proper techniques of euthanasia may contact RAR. RAR will euthanize rodents at no charge for investigators; euthanasia of non-rodents will be charged time and materials.  For more information, see http://www.ahc.umn.edu/rar/acservices.html#Euthanasia.

 

NOTE: You may only use a euthanasia method that is approved in your IACUC Animal Care and Use Protocol. A change in euthanasia method, including dose or route of administration, is a significant change in protocol and must be reviewed and approved by the IACUC before implementation.

CRITERIA FOR EUTHANASIA

Euthanasia of animals is expected if animals demonstrate the conditions listed below, whether the animal has been manipulated or not. Additional criteria may be specified on the Animal Usage Form. Fulfillment of one criterion can constitute grounds for euthanasia. Exceptions are permitted only if approved by the IACUC as part of the protocol review process (i.e. the clinical signs listed below are expected as part of the experiment and appropriate measures are taken to minimize pain or discomfort in the animals). 

  1. Weight loss: loss of 20-25% (depending on attitude, weight recorded at time of arrival, and age: growing animals may not lose weight, but may not gain normally) or if not measured, characterized by cachexia and muscle wasting.
  2. Inappetance: complete anorexia for 24 hours in small rodents, up to 5 days in large animals; partial anorexia (less than 50% of caloric requirement) for 3 days in small rodents, 7 days in large animals.
  3. Weakness/inability to obtain feed or water: Inability or extreme reluctance to stand which persists for 24 hours, assuming that the animal has recovered from anesthesia.
  4. Moribund state: In rodents, measured by a lack of sustained purposeful response to gentle stimuli (example of purposeful response- weak attempt to get up; if animal is on its side, attempts should be asymmetrical in nature); in larger animals, measured by depression coupled with body temperature below 99F (assuming in either case that the animal has recovered from anesthesia).
  5. Infection: infection involving any organ system (either overt, or indicated by increased body temperature or WBC parameters) which fails to respond to antibiotic therapy within an appropriate time and is accompanied by systemic signs of illness.
  6. Signs of severe organ system dysfunction non-responsive to treatment, or with a poor prognosis as determined by an RAR veterinarian:
    Respiratory: dyspnea, cyanosis. 
    Cardiovascular: blood loss or anemia resulting in hematocrit below 20%; one transfusion may be performed. 
    Gastrointestinal: severe vomiting or diarrhea, obstruction, intussuception; peritonitis, evisceration (immediate euthanasia required). 
    Urogenital: renal failure characterized by elevated BUN, creatinine or uroperitoneum. 
    Nervous: CNS depression, seizures, paralysis of one or more extremities; pain unresponsive to analgesic therapy. 
    Musculoskeletal: muscle damage, bone injury, locomotor defecits, etc. resulting in inability to use the limb, unless anticipated as part of the study. 
    Integumentary: Non-healing wounds, repeated self-trauma, second or third degree heating pad burns. 
SURGERY TO CORRECT EXPERIMENTAL COMPLICATIONS

Only one major surgical procedure may be performed per animal, unless indicated on an approved protocol. Therefore, major surgery intended to correct complications arising after a major experimental procedure is not permitted without prior approval. In such cases, euthanasia must be performed. Procedures such as repair of dehiscences and wound cleaning/debridement for treatment of infection may be performed following notification of the RAR veterinary staff. 

Acceptable Methods for Euthanasia of Animals

 

Method

Small birds, poultry, rodents,  Rats weighing < 200 gm, Rabbits < 2kg Rats weighing > 200 gm, all Guinea Pigs Rabbits weighing >2 kg Dogs, Cats, Nonhuman Primates

Farm Animals (e.g. swine,

ruminants and horses)
Amphibians, Reptiles, Fish
Carbon Dioxide A A    AWJ A
A2 for swine <32kg
UNA
A
Barbiturate Overdose/ Euthanasia Solution, Intraveneous (100 mg/kg) A A A A A A
Barbiturate Overdose/ Euthanasia Solution, Intraperitoneal (100 mg/kg) A A A AWJ 4 A3 for nursery pigs
AWJ 4 for adults
A
Anesthesia and Exsanguination A A A A A A
Anesthesia and Intraveneous KCl (1-2 meq/kg) A A A A A A
Anesthesia and Decapitation A A A   UNA   UNA A
Anesthesia and Cervical Dislocation A A A   UNA   UNA A
Decapitation of Conscious Animal

   A

   A

  UNA

  UNA   UNA    AWJ
Cervical Dislocation of Conscious Animal

   A

UNA

   A

  UNA   UNA   UNA
Other

For guidelines on euthanasia of rodent fetuses and neonates click HERE

 

UNA - Small bird thoracic compression
      Stunning or electrocution followed by exsanguination may be used for on-farm or slaughterhouse euthanasia.  Rifle shot may be used for field euthanasia where restraint is not possible 

A - Immersion in MS-222 (tricaine) or benzocaine at 2 g/L water 

A - hypothermia of amphibians or fish weighing <4 g (0.1 oz) in liquid N

A - rapid chilling (not freezing) of zebrafish

 

Volatile agents used to euthanize animals should not be stored or used in animal rooms because of improper ventilation, toxicity to laboratory animals, and possible effects on experimental results.

Always UNACCEPTABLE in conscious animals: KCl, MgSO4, strychnine, neuromuscular blocking agents, exsanguination, air embolism, ether, chloroform, carbon monoxide.

Ether is irritating, flammable and explosive, and should not be used in animal rooms. In addition, animals euthanized with ether must be left in a fume hood for several hours so that the carcasses are not explosive when disposed of. Precautions on ether use are available from DEHS

Chloral hydrate and alpha chloralose used as sole agents are not adequate to reliably achieve euthanasia

Abbreviations:

  • A = Acceptable
  • AWJ = Acceptable only with scientific justification reviewed and approved by the IACUC that another method would interfere with the goals of the experiment
  • UNA = Unacceptable

1 Acceptable when performed by individuals with a demonstrated high degree of technical proficiency. In lieu of demonstrated technical competency, animals must be unconscious or anesthetized prior to cervical dislocation or decapitation.

2 Swine <32 kg may be euthanized with CO2 in an appropriate chamber by trained personnel.
3 Neonatal swine may be euthanized by IP barbiturate injection.
4 Intraperitoneal or intracoelomic injection may be used in situations when an IV injection would be distressful, dangerous, or difficult due to small patient size.
5 While CO2 is an effective method of euthanasia, its use as the sole agent in rabbits can result in apparent distress. Premedication with sedative agents is expected unless an exception is justified to, and approved by, the IACUC.

Standard Euthanasia Methods for Commonly Used Species 

Below are a set of standard acceptable euthanasia methods.  You may cut and paste them into the Animal Care and Use Protocol (ACUP) form, section 6C.1).  Please contact the IACUC or RAR veterinary staff if you have any questions about these methods or would like training in the use of these methods. 

 

Rodents (Mice, Rats, Gerbils, Hamsters, Guinea Pigs, etc.)

  • Carbon dioxide (CO2) To effect  (review guidelines here)
  • Sodium Pentobarbital 100 or > mg/kg IV, IP
  • Commercial Euthanasia Solution (Sodium pentobarbital 390 mg + sodium phenytoin 50 mg/ml) (e.g. Beuthanasia®, Euthasol®, Fatal-Plus®, Somlethal®) 0.22 ml/kg IV, IP (~86 mg/kg pentobarbital)
  • Decapitation or cervical dislocation of anesthetized animals (anesthesia details must be specified in ACUP)
  • Cervical dislocation of conscious mice by individuals that have demonstrated a high degree of technical proficiency. In lieu of demonstrated technical competency, animals must be unconscious or anesthetized

 

Rabbits

  • Sodium Pentobarbital 100 or > mg/kg IV, IP
  • Commercial Euthanasia Solution (Sodium pentobarbital 390 mg + sodium phenytoin 50 mg/ml) (e.g. Beuthanasia®, Euthasol®, Fatal-Plus®, Somlethal®) 0.22 ml/kg IV, IP (~86 mg/kg pentobarbital)
  • Exsanguination under anesthesia (anesthesia details must be specified in ACUP)

Cats and Dogs

  • Sodium Pentobarbital 100 or > mg/kg IV
  • Commercial Euthanasia Solution (Sodium pentobarbital 390 mg + sodium phenytoin 50 mg/ml)(e.g. Beuthanasia®, Euthasol®, Fatal-Plus®, Somlethal®) 0.22 ml/kg IV (~86 mg/kg pentobarbital)
  • Potassium chloride under anesthesia to effect (anesthesia details must be specified in ACUP)

 

Livestock (Cattle, Goats, Horses, Sheep, and Swine

  • Sodium Pentobarbital 100 or > mg/kg IV
  • Commercial Euthanasia Solution (Sodium pentobarbital 390 mg + sodium phenytoin 50 mg/ml) (e.g. Beuthanasia®, Euthasol®, Fatal-Plus®, Somlethal®) 0.22 ml/kg IV (~86 mg/kg pentobarbital)

 

Nonhuman Primates

  • Sodium Pentobarbital 100 or > mg/kg IV, IP
  • Commercial Euthanasia Solution (Sodium pentobarbital 390 mg + sodium phenytoin 50 mg/ml) (e.g. Beuthanasia®, Euthasol®, Fatal-Plus®, Somlethal®) 0.22 ml/kg IV, IP (~86 mg/kg pentobarbital)

Amphibians and Fish

  • Sodium Pentobarbital 100 or > mg/kg IV, ICL
  • Commercial Euthanasia Solution (Sodium pentobarbital 390 mg + sodium phenytoin 50 mg/ml) (e.g. Beuthanasia®, Euthasol®, Fatal-Plus®, Somlethal®) 0.22 ml/kg IV, ICL (~86 mg/kg pentobarbital)
  • Benzocaine hydrochloride 250 mg/liter (Water bath)
  • Tricaine methane sulfonate (e.g. MS-222®) 3 g/liter (Water bath buffered with sodium bicarbonate)

Birds

  • Carbon dioxide (CO2) To effect
  • Sodium Pentobarbital 100 mg/kg IV, ICL
  • Commercial Euthanasia Solution (Sodium pentobarbital 390 mg + sodium phenytoin 50 mg/ml) (e.g. Beuthanasia®, Euthasol®, Fatal-Plus®, Somlethal®) 0.22 ml/kg IV, ICL (~86 mg/kg pentobarbital)

 

Reptiles

  • Sodium Pentobarbital 100 or > mg/kg IV, ICL
  • Commercial Euthanasia Solution (Sodium pentobarbital 390 mg + sodium phenytoin 50 mg/ml) (e.g. Beuthanasia®, Euthasol®, Fatal-Plus®, Somlethal®) 0.22 ml/kg IV, ICL (~86 mg/kg pentobarbital)

 

Abbreviations

IC = intracardiac

ICL = intracoelomic

IP = intraperitoneal

IV = intravenous

 


USE OF THE CO2 CHAMBER FOR EUTHANASIA OF RODENTS

NOTE:  RAR Animal Facilities have instructions posted for CO2 euthanasia based on whether the carbon dioxide cylinder is a regulator unit or a flow meter unit.   Click HERE to read about the difference.  

 

DIRECTIONS FOR USE OF REGULATOR DELIVERED CO2 IN NON-RAR MANAGED AREAS:

1. Whenever possible, euthanize animals in their home cage rather than transferring them to a new cage or chamber.

2. Do not pre-fill the cage or chamber with CO2.

3. Open the CO2 tank or valve regulator to initiate flow of gas.

4. Verify that the regulator reads the correct psi (pounds per square inch) based on instructions posted by the unit or adjust the regulator as needed to the correct psi which is typically no higher than 5 psi .

5. Fill slowly - flow rate should displace no more than 30% of chamber/cage volume per minute.

  • For a typical mouse cage this would be ~2 liters/minute.
  • For a typical rat cage this would be ~7.5 liters/minute.

6. Wait approximately 3-5 minutes for animal to stop moving or breathing. Eyes should be fixed and dilated

7. Turn off CO2 tank or regulator valve to stop the flow of CO2.

 

VERIFICATION OF COMPLETE EUTHANASIA IS MANDATORY.  THE ANIMAL IS NOT DEAD IF:

  1. Its heart is beating, check this by feeling the chest between your thumb and forefinger.
  2. It blinks when you touch the eyeball.
  3. If the animal is not dead, place it back in the chamber, recharge and wait another 5 minutes or, use scissors to open the chest cavity and create a pneumothorax. MAKE SURE THE ANIMAL IS NOT AWAKE WHEN YOU DO THIS!

NOTE: Neonates and fetuses are resistant to carbon dioxide euthanasia. See NIH guidelines on euthanasia of rodent neonates and fetuses for guidance.

Top of page

 



The information contained in this site is intended as a reference for University of Minnesota investigators, and animal husbandry and veterinary staff. Drug information and dosages are derived from a variety of sources and do not necessarily guarantee safety or efficacy. Information obtained through this site should not be relied upon as professional veterinary advice. Any medications administered or procedures performed on animals should only be performed by or under order of a qualified, licensed veterinarian.