Euthanasia with Carbon Dioxide
The CO2 chamber may be used to euthanatize rats, mice, guinea pigs, hamsters, chickens, and gerbils. Immature animals may require more exposure time to produce unconsciousness and death. Rodents 10 days of age are resistant to the effects of CO2 and need to be euthanatized by other methods.
The 2013 AVMA Guidelines on Euthanasia recommendations for the use of Carbon Dioxide for euthanasia of small animals are as follows:
Ø Compressed CO2 gas in cylinders is the ONLY recommended source of carbon dioxide.
Ø Species should be separated and euthanasia chambers should not be overcrowded.
Ø An optimal flow rate should displace at least 10-30% of the chamber volume per minute.
Ø Gas flow should be maintained for at least 1 minute after apparent clinical death.
Ø It is essential to verify that an animal is dead before disposal of the carcass.
Investigator's responsibilities include:
Ø Following the above AVMA Guideline’s for euthanasia.
Ø Proper bagging of carcasses prior to placing in freezer.
Ø Return of empty cages to G10.
Ø Clean tables, countertops and/or sink area with Quatricide
Ø Sweep up any debris on floor and mop if needed.
To Operate CO2 Chamber:
1. Leave the rodents in their home cages to minimize stress.
2. Choose the appropriately sized stainless steel or plastic chamber lid to fit over the cage.
3. Snap on the CO2 quick connect fitting to the chamber lid. Make sure it has snapped on completely.
4. Place lid on cage of animals to be euthanatized.
5. Turn the flow meter valve on at the wall connection by turning the knob counterclockwise and set the flow rate as defined below based on cage size.
6. For small lid (mouse cage): The flow rate for this size of cage has been pre-determined to be 2 liters per minute. Maximum amount flowing must be at least 2 liters per minute to minimize distress to the animals and meet the criteria of the AVMA Guidelines on Euthanasia.
7. For large lid (static rat cage): The flow rate for this size of cage has been pre-determined to be 7 liters per minute for the euthanasia of rats. Maximum amount flowing must be 7 liters per minute to minimize distress to the animals and meet the criteria of the AVMA Guidelines on Euthanasia.
8. For large lid (mouse vent cage): The flow rate for this size of cage has been pre-determined to be 3 1/2 liters per minute. Maximum amount flowing must be at least 3 1/2 liters per minute to minimize distress to the animals and meet the criteria of the AVMA Guidelines on Euthanasia.
9. For rat vent cage: The flow rate for this size of cage has been pre-determined to be 8 liters per minute. Maximum amount flowing must be at least 8 liters per minute to minimize distress to the animals and meet the criteria of the AVMA Guidelines on Euthanasia.
10. Continue to allow the gas to flow for approximately 1 minute after apparent death (immobile and no respiration).
11. Shut off the CO2 by turning the flow meter knob clockwise until snug but do not over tighten.
12. Examine rodents to ascertain death as evidenced by pale eyes and the absence of heartbeat, respiration for at least 1 more minute. Alternately complete cervical dislocation or thoracic wall incision to assure that the animals do not recover from euthanasia.
13. Once death has been ensured, remove animals from cage and place in a plastic bag.
14. If animal is to be incinerated, place in freezer in room G97.
15. If you wish to save the carcass for necropsy, indicate SAVE on tag with animal ID’s, investigator's name, date, and protocol number and place in refrigerator in room G29. Animals will be held for 48 hours for necropsies.
16. Enter, in euthanasia log, the information requested for the applicable animals being euthanatized.
17. Disconnect the CO2 tubing from chamber lid and wipe the lid down with Quatricide.
18. Clean cart area with Quatricide.
19. Sweep up any debris on floor and mop if needed.
20. Transport all soiled cages to G10 for cleaning.