Basic Biomethodology
For Laboratory Mice

Your veterinarian should always be consulted for advice on selection and administration of euthanasia agents.

The euthanasia method selected for use must be described in detail in your approved Animal Study Proposal.

Refer to NHGRI Guideline 01.1 "Euthanasia of Rodents" and the AVMA Panel on Euthanasia for additional information.

CO2

Compressed CO2 gas is the only recommended source of CO2 for euthanasia.

Carbon dioxide generated from dry ice is unacceptable.

With an animal in a chamber, an optimal flow rate should displace 10 - 20% of the chamber volume per minute until the mouse is unconscious.

This flow rate is associated with a rapid loss of consciousness and minimal distress to the animal.

Once the mouse is unconscious, the flow rate can be increased.

Gas flow should be maintained for at least 1 minute following apparent clinical death.

Death should be verified by the absence of the heartbeat, performing cervical dislocation or by perforating the diaphragm prior to proper disposal of the animal.

Revised 4/6/04 15

Injectable

Injectable anesthetics can also be used for euthanasia, when administered at higher doses.

Barbiturate anesthetics produce rapid and humane euthanasia when injected intraperitoneally.

Barbiturates are controlled substances and must be procured through your Controlled Substances Officer.

The user of controlled substances is accountable for strict record-keeping procedures.

Inhalant

Inhalant anesthetics can also be used for euthanasia of rodents.

Halothane is the most effective inhalant anesthetic for euthanasia, but isoflurane is also acceptable.

Inhalant anesthetics used for euthanasia are best utilized with the open drop method using a closed receptacle containing cotton or gauze soaked with the liquid.

Care must be taken to prevent direct contact of the animal with the liquid anesthetic.

The anesthetic can also be introduced through a vaporizer, but this will increase the time required to achieve euthanasia.

Inhalant anesthetics must be used with a down draft table, in a type IIB2 biosafety cabinet vented to the outside or in a chemical fume hood.

Physical

Cervical dislocation, when properly performed, is a humane method of euthanasia.

Anesthetics or CO2 must be used to narcotize mice prior to cervical dislocation or other physical methods of euthanasia.

Physical methods of euthanasia, for example cervical dislocation or decapitation, can be performed without prior narcotization only if scientifically justified in the Animal Study Proposal and approved by the Animal Care and Use Committee.

Fetuses and neonates are resistant to many methods of euthanasia.

Special considerations must be given to this age group and are addressed in the NIH ARAC "Guidelines for the Euthanasia of Mouse and Rat Fetuses and Neonates".

This document is found in the reference section.

Remember

• Your veterinarian should always be consulted for advice on selection and administration of euthanasia agents.
• Inhalant anesthetics must be used on a downdraft table, in a type IIB2 biosafety cabinet or in a chemical fume hood.
• Narcotization is required prior to the use of cervical dislocation.
• For the proper methods of euthanasia for fetuses and neonates, Refer to NIH ARAC "Guidelines for the Euthanasia of Mouse and Rat Fetuses and Neonates".