Rapidly occurring unconsciousness followed by respiratory and cardiac arrest is required for the method to be acceptable. At the conclusion of the euthanasia procedure, a follow-up exam is required to confirm the absence of a heartbeat. There are horror stories of animals assumed to be dead who reportedly begin to revive later. The investigator has the responsibility of choosing a proper euthanasia method both on ethical grounds and on the compatibility with the experimental data needed from postmortem examinations. Euthanasia may be required during the course of an experiment.
Investigators have a moral obligation to alleviate unnecessary pain and suffering.
It is sometimes difficult to recognize pain and suffering and species may vary in their manifestations. All personnel working with animals should be familiar with the signs of pain and suffering in their particular species. Clinically obvious depression, loss of appetite and vocalization are possible signs of stress and pain. Euthanasia is the act of killing animals by methods that induce rapid unconsciousness and death without pain or distress. Euthanasia might be necessary at the end of a protocol or as a means to relieve pain or distress that cannot be alleviated by analgesics, sedatives, or other treatments.