A. R. Michell believes that animal owners and vets today are prolonging the lives of some pets unnecessarily

It may still be unacceptable to practise euthanasia - gently inducing death to avoid continued suffering -among humans. But it has long been a privilege of veterinary medicine that when an animal's suffering is unacceptable, euthanasia is an option. Nonetheless, even here it arouses strong emotions, in owners, clinicians, nurses and students; often these are not expressed or even clearly understood.

Humans, if mentally sound, have a right to refuse treatment and to overrule it would be assault. Animals do not have this defence. Legally the judgement of their best interest lies with the owner. In the absence of cruelty, veterinary surgeons can only advise. I am uneasy, I do not see that an owner's enthusiasm for dubious remedies should cause them to be inflicted on their animals.

I have real fears about the transfer to animals of high-cost, high-stress techniques, such as renal transplants. I worry about the donors (if living), the suitability of the donated kidneys and the unpleasant side-effects of rejection and the drugs used to avoid it. Such fears have to be balanced with the danger of stifling progress. Clinical advances often cause distress until they improve with experience. And when vets explain that euthanasia is the most humane option for an animal, they must remember that the owner or a relative may have a similar disease.

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People used to fear to take pets to the vet in case he decided to put them to sleep. I now fear that clinicians are reticent to extend this merciful release to animals whose quality of life no longer justifies the clinical battle to extend it. Paradoxically, vets may be criticised for failing to do for their patients what doctors are legally prevented from doing for theirs.

I wish that euthanasia, in certain circumstances and with adequate safeguards, were also available to humans. Modern therapeutics have removed some relatively acute causes of death, increasing the possibility of a twilight period of life of dubious quality. The problem is that we adjust our expectations to our limitations:age is an ever-receding horizon. Similar adjustment occurs with veterinary patients -but in owners or clinicians. My most recent dog ended her life aged 16 after euthanasia. Perhaps I kept her going a year longer than I should have, not causing suffering, but exaggerating the delight at glimpses of her prime.

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There are many objections to human euthanasia, above all the sanctity of human life. Even clinicians who have overcome ethical objections say they would not like to have to do it. Perhaps centuries of war and a mere half century of truly powerful medical remedies still leave us lamenting those who die too young, rather than those who live too long.

A more recent problem is that clinical cases can too readily be perceived as intellectual challenges. But clinical decisions go beyond what is feasible to what is appropriate to the patient's peace of mind. The twin dangers are that lack of a solution undermines clinical motivation while the solution may push the patient beyond reasonable endurance. Overzealous treatment can arise from clinical ambition, fear of failure or fear of litigation.

The law gives good protection to humans, short of allowing euthanasia. Last year, barrister Margaret Brazier wrote in the British Medical Journal: "The patient's condition may be such that prolonging life simply extends the suffering. There is almost always some means available to extend life, to prolong the process of dying. The law is unlikely to, and would be wrong to, demand that all available means be employed to do so."

Professor A. R. Michell works at the Animal Health Trust, Newmarket.

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