CO2 CHAMBER PROCEDURES
(To be posted at every location where CO2 euthanasia is performed.)

 

Carbon dioxide (CO2) asphyxiation is an approved method of euthanasia for rodents, but must be performed properly to be effective and humane.  The following procedures are designed to assure that CO2 euthanasia is performed properly.

1.           CO2 euthanasia is only appropriate when approved as part of an animal use protocol approved by the Rutgers Animal Care and Facilities Committee.

2.           Personnel performing CO2 euthanasia must be trained to do so.

3.           Animals may be exposed to CO2 in their home cage or by placing the animals in a secondary container that is more easily sanitized.  Either procedure will make it easier to keep the euthanasia apparatus clean and free of debris.

4.           Animals may be euthanized singly or in groups.  Each animal should have space to stand on all four feet and have sufficient space to turn around.

5.           The gas flow rate should provide a balance between the time to unconsciousness and the adverseness of noise or high-velocity air movement from too-high flow rates.  A fill rate of 20% of the chamber volume per minute is recommended.

6.           Pre-filling the chamber is not necessary and is not recommended.

7.           CO2 is heavier than air.  Excess gas must be allowed to exit from the top of the chamber.

8.           The euthanasia chamber and/or lid should be transparent.  You must be able to see animals without opening the chamber.

9.           Euthanasia chambers must be kept clean and free of debris and excreta. 

10.       Animals undergoing CO2 euthanasia should not be left unattended until death is assured.

  1. Observation – if another method of assuring death is not used, animals should be observed in the chamber for a minimum of 5 minutes and then for an additional period of 5 minutes exposed to room air.  A timer must be available for timing the observation period.

12.       Dry ice is not an acceptable means of producing CO2 gas.  The CO2 source must be a compressed gas cylinder.  100% CO2 is recommended.

13.       A compressed air tank should not be used without a regulator.

14.       The above procedures are for adult animals.  Neonatal and fetal rodents are very resistant to CO2 euthanasia and special procedures are required.

ASSURING DEATH
FOLLOWING CO2 EUTHANASIA

 

(TO BE AVAILABLE TO OPERATORS OF C02
EUTHANASIA EQUIPMENT AT EACH LOCATION)

 

Inadequate exposure time to CO2 may result in animals that appear dead but can awaken from deep anesthesia.  One of the following procedures MUST be followed to assure death:

    1. Observation – if another method of assuring death is not used, animals should be observed in the chamber for a minimum of 5 minutes and then for an additional period of 5 minutes exposed to room air.  A timer must be available for timing the observation period.
    2. Cervical dislocation – animals that are fully unconscious may be killed by cervical dislocation.  This procedure is limited to mice, or rats less than 200g.
    3. Decapitation
    4. Thoracotomy of deeply anesthetized or dead animals–

                                                              i.      Stab wound into the thorax

                                                            ii.      Open the chest wall

                                                          iii.      Open the abdomen and incise the diaphragm

    1. Experimental procedures on deeply anesthetized or dead animals which assure death by another means (e.g. exsanguinations, organ removal resulting in exsanguinations, thoracotomy, decapitation).

 

 

REFERENCES:

  1. 2000 AVMA Panel on Euthanasia
  2. Report of the ACLAM Task Force on Rodent Euthanasia, American College of Laboratory Animal Medicine, 2005
  3. Guide for the Care and Use of Laboratory Animals, 1996
  4. Rutgers Policy on Rodent Euthanasia