While it may be regarded by some as inhumane or unethical to take any life, mankind, as responsible stewards of animals, is obliged to do so for many reasons: for food, health, population control, to alleviate incurable suffering, etc. Yet beyond the ironies and ethical dilemmas of the right to life versus the right to take life, lies the necessity to destroy life. This entails an enormous ethical responsibility relevant to the times, and also the moral injunction that the method of killing be humane, in other words, causing the least possible distress, physically and psychologically. This injunction implies, therefore, that there is an obligation (as a final ethical responsibility and demonstration of respect for the life that is to be terminated) to utilize the best available method of euthanasia: to induce a painless death. There are also economic and aesthetic considerations and other situational variables which make this an extremely complex issue. When "euthanasia" must be administered, if it is to be humane, there should ideally be no distress: most authorities agree that many methods are far from this ideal and, to date, at best we have only a hierarchy of more or less distressing methods to choose from.
Many veterans are of the opinion that there is only one, possibly two, killing methods known to be capable of routinely invoking death without suffering, namely intravenous injection of certain barbituate compounds, and shooting. Of the unknown millions of dogs and cats which are killed each year throughout the world, those which benefit from euthanasia are an insignificant percentage.
Further research may provide us with the "ideal" method that satisfies all criteria in all contexts or it may show us that, from the hierarchy of lesser and greater distressful methods, which one is the least distressing and also the most appropriate for a given context/situation. A compromise between humane ethics and the variables of context and available methods should not be regarded, however, as an acceptable solution. The search for a humane solution to animal euthanasia under various conditions is an ethical imperative for all those in whose care or jurisdiction rests the life and well-being of our animal kin. This has reached a critical point today because of the need to destroy on a mass scale, millions of unwanted pets (13-15 million cats and dogs per annum in the U.S. alone). Until the causes of this population explosion can be rectified, mass destruction of pets will continue and so must the search for an optimal method of euthanasia for all concerned.
Carding, T. and The Institute for the Study of Animal Problems, "Euthanasia of Dogs and Cats: An Analysis of Experience and Current Knowledge With Recommendation for Research" (1978). EUTHANASIA. 1.