The medical gains: Even veterinary science has benefited from testing

Every year more than two and a half million animals suffer and die in British laboratories in the cause of human health. At least 50 million do so worldwide. And millions more - bred for experiments but judged unsuitable or surplus to requirements - are killed without being used.

Every year more than two and a half million animals suffer and die in British laboratories in the cause of human health. At least 50 million do so worldwide. And millions more - bred for experiments but judged unsuitable or surplus to requirements - are killed without being used.

For years the toll has been posing a moral dilemma, fuelling deep passions. But it has rarely risen to political consciousness. Last week it did so with a vengeance, focusing on the controversial Cambridgeshire laboratory of Huntingdon Life Sciences.

Peaceful, hitherto largely unpublicised, protest - and downright intimidation - has brought the company to its knees, making it a test case for the future of animal experiments in Britain. As it struggled to find funds last week, its share price reached a single penny, down from more than £3.50 at their peak. Protesters, who have been camped outside the laboratory's gates for more than a year, called its work "cruel and immoral". The Prime Minister's spokesman, in turn, accused the more militant campaigners - who have firebombed cars and threatened staff - of "intimidation, thuggery and violence". And ministers have scrambled to provide extra policing and to change the law to protect employees and their families.

Animal testing has long polarised views. The British Union for the Abolition of Vivisection (BUAV) says that the experiments "involve animals being poisoned, starved, blinded, deprived of water, subjected to electric shocks, subjected to invasive surgery and infected with dangerous diseases". It calls the tests "cruel and unscientific". And the protesters at the laboratory, where cruelty was exposed four years ago, say that when they have closed it they will "move on somewhere else, until all animal testing is banned in this country".

Polls of doctors and scientists, on the other hand, record a near-unanimous conviction that animal experiments have made an important contribution to medical progress and will be equally vital in future. The Research Defence Society says: "We would be very unlikely to achieve many significant advances in scientific understanding or the prevention and treatment of diseases without animal research."

Animal testing has in fact declined sharply in the past quarter of a century. Only half as many experiments are now carried out in Britain as in the Seventies, and there are fewer now than since the mid-Fifties. Nevertheless, most of the fall was in the Eighties, and the trend has levelled off in the past five years. The slack has been taken up by a rapid rise in tests on genetically engineered animals, which have increased more than tenfold over the past decade; many are modified to be susceptible to particular diseases to try to help scientists to find cures. And campaigners predict that cloning and using animals to grow organs for human transplant will add new dimensions.

Rats, mice and other rodents make up 86 per cent of the animals used. Dogs (used for studying the heart, lungs and brain vessels) and cats (hearing and the workings of the brain) make up only 0.4 per cent; they are specially bred for the research. Monkeys and apes (used in the study of such conditions as Aids and Alzheimer's disease) comprise just 0.2 per cent.

About four in every 10 experiments are aimed at developing specific new treatments for diseases. Another three are directed at fundamental research to try to find out how the body works, and what goes wrong when disease strikes. Most of the rest are taken up with genetically-engineered animals, and testing other chemicals for safety. In all, it takes up just 10 per cent of medical research. A new medicine, say doctors, is usually tried on more people than animals before it is put into general use.

Animal testing has a long history. Galen, the second century AD Greek physician, worked with animals, while the great William Harvey used them four centuries ago to work out how blood circulates in the body. But the modern use of animal testing, the first British controls and the ethical debate all stem from the second half of the 19th century.

Proponents often point out that since then, life expectancy has almost doubled. This is misleading, as a great deal of the improvement in health over the period was due not to drugs but to improved nutrition and sanitation. Yet it is even more misleading to infer, as opponents often go on to do, that animal testing has therefore brought little benefit. Experiments on animals have been at the heart of almost every major medical breakthrough of the past century.

The vaccines that have all but eradicated diseases such as polio and diphtheria were developed with them. So were antibiotics, anaesthetics, transplants, blood transfusions, insulin (which alone is estimated to have saved 10 million lives) and treatments for asthma, cancer and high blood pressure. New research is offering hope for defeating such scourges as Alzheimer's, motor neurone disease, multiple sclerosis, Parkinson's and muscular dystrophy - and for developing vaccines for diseases such as malaria that ravage the Third World.

Even animals have benefited, for veterinary medicine, too, has relied on animal research. Tests on a few hundred dogs helped to provide a vaccine for distemper, which protects seven million British pets.

The Government has done more than any of its predecessors to limit the experiments. It has stopped tests for cosmetics and promised they will never be allowed for tobacco or alcohol. It has banned the use of great apes, such as chimpanzees or gorillas. And it has ended the notorious LD 50 test - which poisoned animals until half of them died - for toxicity experiments.

Alternatives are being developed for other tests, such as those used for cancer-causing substances and for skin irritation. Animals are not allowed to be used in Britain if other approved methods are available. But progress is slow, and regulatory bodies are often reluctant to adopt new techniques. Such research must be increased and, in the meantime, experiments must be made as humane as possible. But it is hard to disagree that, where there is no alternative, the benefits of properly conducted research outweigh the suffering it causes.