Institutional Animal Care and Use Committee

CO2 Euthanasia of Rodents

Federal regulations as well as EINSTEIN policy have been adopted requiring that carbon dioxide used for euthanasia of rodents must come from a compressed gas cylinder source. The regulatory basis of the requirement is highlighted at the end of this message.

If you wish to use carbon dioxide to euthanize your animals, you must use a compressed gas source.

Each of our animal facilities is equipped with a carbon dioxide euthanasia chamber supplied by compressed gas cylinders.These chambers are located in Chanin 617, Kennedy B-25 (hallway), and Ullmann 1008. If your experimental needs will allow it, you can euthanize your mice at one of these locations before bringing them to the laboratory.

If the animals must be euthanized in the laboratory, then Tech Air or other suitable vendor can supply you with the necessary regulator and rent you a carbon dioxide cylinder. To complete the set up you will need to attach a length of tubing connected to a desiccator jar or something similar to act as the actual euthanasia chamber. Both of which can be easily and inexpensively obtained from Fisher Scientific or other suitable vendor. Please note, some parts of the Chanin building have a carbon dioxide house line that can be used to supply a euthanasia chamber. If you have access to that line, you will only need the tubing and a suitable container to use as the euthanasia chamber.

If none of these options are acceptable for you, you will have to switch to an alternative euthanasia method.  As a reminder, the use of dry ice to generate carbon dioxide for euthanizing your animals is a violation of the regulations and EINSTEIN policy. Violation of the regulations and/or EINSTEIN policy risks suspension of your animal use protocol(s) by the IACUC, which requires notification of the Dean, regulatory authorities and funding agencies.

Please contact any of the IAS veterinarians if you wish to discuss alternative euthanasia methods or would like more information on carbon dioxide euthanasia options. Thank you very much for your time, understanding, and prompt attention to this matter.

Excerpt from the Report of the AVMA Panel on Euthanasia:

Recommendations—Carbon dioxide is acceptable for euthanasia in appropriate species (Tables 1 and 2). Compressed CO2 gas in cylinders is the only recommended source of carbon dioxide because the inflow to the chamber can be regulated precisely. Carbon dioxide generated by other methods such as from dry ice, fire extinguishers, or chemical means (eg, antacids) is unacceptable. Species should be separated and chambers should not be overcrowded. With an animal in the chamber, an optimal flow rate should displace at least 20% of the chamber volume per minute.85 Loss of consciousness may be induced more rapidly by exposing animals to a CO2 concentration of 70% or more by prefilling the chamber for species in which this has not been shown to cause distress. Gas flow should be maintained for at least 1 minute after apparent clinical death.86 It is important to verify that an animal is dead before removing it from the chamber. If an animal is not dead, CO2 narcosis must be followed with another method of euthanasia. Adding O2 to the CO2 may or may not preclude signs of distress.67,87 Additional O2 will, however, prolong time to death and may complicate determination of consciousness. There appears to be no advantage to combining O2 with carbon dioxide for euthanasia.87

JAVMA, Vol 218, No. 5, March 1, 2001 Report of the AVMA Panel on Euthanasia, p. 677-678

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