Nitrogen inhalation as a method of euthanasia in dogs.

Thirty-four dogs were euthanatized in a chamber flushed with pure nitrogen. Electroencephalograms and arterial blood pressure, recorded during euthanasia, showed the dogs to be unconscious in an average time of 40 s and to be dead in 204 s. The dogs displayed no detectable signs of pain before unconsciousness occurred. Hypoxia produced by nitrogen inhalation was found to be effective, humane, safe, and economically feasible as a method of euthanasia.