Guidelines

University of Michigan Euthanasia Guidelines

Unit for Laboratory Animal Medicine
Oct 6, 2023 3:00 pm
Login to Bookmark  Share

These guidelines are based on the AVMA Guidelines for the Euthanasia of Animals (2020 Edition).  Abbreviation codes are as follows:

  • A = Acceptable - those which consistently produce a humane death when used as the sole means of euthanasia
  • AC = Acceptable with Conditions - those which consistently produce a humane death when specific conditions are met
  • U = Unacceptable - deemed inhumane under any conditions, or found to pose substantial risk to human applying the technique

  • U-M Euthanasia Guidelines Chart
      SPECIES
    METHOD1, 20 Amphibians Birds Cats,
    Woodchucks    		 Dogs Fish Ferrets,
    Bats    		 Monkeys Rabbits Reptiles Rodents &
    Small Animals    		 Ruminants Swine
    Barbiturates2 A A A A A A A A A A A A
    Injectable anesthetics3 A A A A U A A A A A A A
    Inhalant anesthetics4 U AC AC U U AC AC AC AC AC U U
    Carbon dioxide5 U AC AC U U AC AC AC U AC U U
    Clove Oil, Eugenol, or Isoeugenol6 U U U U AC U U U U U U U
    Microwave irradiation7 U U U U U U U U U AC U U
    Tricaine methanesulfonate8 A U U U A U U U U U U U
    Sodium Hypochlorite Immersion 9 U U U U AC U U U U U U U
    Benzocaine hydrochloride10 A U U U A U U U U U U U
    Cervical dislocation11 U AC U U U AC U AC U AC U U
    Decapitation12 AC AC U U AC AC U AC AC AC U U
    Penetrating captive bolt13 AC U U AC U U U AC AC U AC AC
    Pithing14 AC U U U U U U U AC U U U
    Stunning15 AC U U U AC U U U AC U U U
    Rapid chilling/Hypothermia16 U U U U A U U U U AC U U
    The methods listed below require that animals be anesthetized before euthanasia is performed
    Electrocution17 U U U AC U U U U U U AC AC
    Exsanguination under anesthesia A A A A A A A A A A A A
    Potassium chloride
    under anesthesia18    		 A A A A A A A A A A A A
    Terminal procedures
    (incl. removal of a vital organ and pneuomothorax)    		 A A A A A A A A A A A A
    Rapid freezing under anesthesia 19 AC U U U AC U U U AC AC U U

  • Footnotes
    1. These guidelines are based on the AVMA Guidelines for the Euthanasia of Animals (2020 Edition). Abbreviation codes are as follows: A = Acceptable - those which consistently produce a humane death when used as the sole means of euthanasia, AC = Acceptable with Conditions - those which consistently produce a humane death when specific conditions are met, U = Unacceptable - deemed inhumane under any conditions, or found to pose substantial risk to human applying the technique. Deviations from these guidelines require scientific justification and approval by the IACUC.
    2. Intravenous (IV) injection is the preferred method for euthanasia. Intraperitoneal (IP) or intracoelomic injection may be used in situations when IV injection would be distressful or dangerous. Intracardiac (IC) injection must only be used if the animal is unconscious, or anesthetized.
    3. Chloral Hydrate is unacceptable for euthanasia alone but can be used as an anesthetic followed up with a 2nd method (e.g., removal of vital organ) to ensure death.
    4. Either of equal preference: isoflurane, or sevoflurane, exposure to high concentrations resulting in rapid loss of consciousness is preferred. In rabbits and other species that show aversive reactions to inhaled anesthetics, it is best to pre-anesthetize the animal with a sedative prior to removal from the home cage.
    5. Compressed gas in cylinders is the only recommended source of carbon dioxide because the inflow to the chamber can be regulated precisely. Flow rate should be 30-70% of chamber volume/minute in rodents. For neonates and immature animals, the time required for euthanasia may be prolonged. In small rodents, carbon dioxide exposure must be followed by an active method to ensure death (e.g., bilateral pneumothorax, exsanguination, decapitation, removal of a vital organ). In rabbits, a carefully controlled displacement rate of 50 – 60% must be used. This method is not preferred and must be scientifically justified.
    6. Clove oil, eugenol, or isoeugenol based products must be standardized, with known concentrations of essential oils so that accurate dosing can occur. Fish should be immersed in a tank containing >1.2 g/L anesthetic solution in water for a minimum of 10 minutes following cessation of opercular movement.
    7. For use with small laboratory rodents only. Must be justified to ensure specially designed equipment is used.
    8. Fish 4 days of age or older and amphibians may be euthanized by immersion in a tank containing tricaine methanesulfonate followed by a secondary physical method of euthanasia.
    9. Immersion in sodium hypochlorite (bleach) is appropriate only for zebrafish 3-7 days post-fertilization. Larvae are immersed in a 1% solution of sodium hypochlorite for a minimum of 5 minutes prior to disposal.
    10. Fish and amphibians may be euthanized by immersion in a tank or recirculation system containing benzocaine hydrochloride followed by a secondary physical method of euthanasia.
    11. Manual cervical dislocation is conditionally acceptable in mice, gerbils, hamsters and other small rodents, bats, rats weighing less than 200 gm, and rabbits or ferrets weighing less than 1 kg. Cervical dislocation may be performed on larger rats and rabbits manually by an individual with demonstrated proficiency or if a mechanical dislocator is utilized.
    12. In amphibians and reptiles, decapitation should only be used as part of a three step protocol–animals must be anesthetized prior to decapitation, which must be followed by destruction of both the brain and spinal cord (e.g. pithing). Fish may be euthanized via decapitation without anesthesia, provided the process is performed rapidly and followed by pithing of the brain and spinal cord. Decapitation is acceptable for euthanasia of neonatal rodents less than 10 days of age.
    13. This method requires a secondary method to confirm euthanasia (e.g., exsanguination, etc.). For fish and reptiles, this should only be used in large species.
    14. May be used as only as secondary method of euthanasia in species with anatomic features that facilitate easy access to the central nervous system (e.g., frogs).
    15. Stunning is unacceptable as a sole method of euthanasia. If performed properly, stunning will produce unconsciousness but must be followed by decapitation or pithing to ensure the animal's death.
    16. Rapid chilling of zebrafish >4 days post-fertilization is acceptable as long as transfer to water at temperatures of 2° to 4°C occurs rapidly with as little transfer of warmer water as possible. Adult fish (>14 days post-fertilization) should be left immersed for 10 minutes after loss of opercular movement. Fry (4 – 14 days post-fertilization) should be left immersed for 20 minutes after cessation of opercular movements, followed by a secondary method of euthanasia.  Rapid chilling is not appropriate for other species of fish, especially larger or cold-adapted species.  Hypothermia is an acceptable method of anesthesia for neonatal rodents, however it requires a secondary method of euthanasia to ensure death and cannot be used as a sole means of euthanasia. As cold surfaces can cause tissue damage and presumably pain, a method to prevent the animals from coming into direct contact with ice must be provided.
    17. Electrodes must be placed such that the animal is rendered unconscious prior to or simultaneously with cardiac fibrillation. Dogs must first be rendered unconscious by an acceptable means (e.g. general anesthesia.)
    18. The only acceptable routes of administration are IC and IV.
    19. Rapid freezing (e.g., liquid nitrogen) should only be used for adult and larval fish, reptiles and amphibians weighing <4g and <5-day-old altricial rodents. In all cases, animals must be anesthetized or rendered unconscious prior to freezing.
    20. Unacceptable methods for any species include: chloroform, carbon monoxide, formaldehyde, and non-penetrating captive bolt.
Species: USDA Other Swine Sheep Rats Rabbits Primates Other Rodents Mice Cats Hamsters Guinea Pigs Fish, Amphibians, and Reptiles Ferrets Dogs Cows Chickens/Avian
Topic: Euthanasia
Questions?

Questions or concerns about these or other animal care SOPs and guidelines should be directed to your ULAM Faculty Veterinarian. General questions may also be submitted to the Unit for Laboratory Animal Medicine (ULAM) at [email protected] or (734) 764-0277.

Related Documents

AVMA Guidelines for the Euthanasia of Animals (2020 Edition)