Euthanasia is the final welfare decision for laboratory animals. Method selection significantly affects whether animals experience pain, distress, or awareness during the dying process.
Euthanasia method selection is a welfare-critical decision because inappropriate methods can cause significant distress, pain, or prolonged dying that negates the purpose of ending animal life humanely. Carbon dioxide, though widely used for cost and convenience, causes aversive sensations including burning of respiratory mucosa before unconsciousness, making it a welfare compromise rather than an ideal agent. Alternative methods including inhalant anesthetic overdose eliminate the aversive phase while maintaining practical applicability for most laboratory settings. Institutional euthanasia protocols that specify approved methods, required training, and monitoring for technique adequacy represent minimum standards for ensuring that the final moments of laboratory animal lives are managed with appropriate care and skill.