Any comparison between life at the end of the last century and life at the end of this one would highlight the enormous advances in medicine which many people nowadays take almost for granted. Certainly, an immense reduction in the death rate from infectious diseases had been achieved by 1900, principally by clean water and good sanitation, but there was still very little that medicine could do for sick people. There were no antibiotics, no vaccines, no insulins, no pharmaceuticals to treat high blood pressure, ulcers, cancer or mental illness. Surgery was severely limited by the serious toxicity of the only anaesthetics then available: ether and chloroform.
All the medical advances of this century have been the product of both basic and applied research. Although this research has relied on the full range of techniques available, it would have been impossible without animal experiments. Indeed, if one reviews the history of medical science, it is clear that every major medical advance has depended on animal experiments. The crucial test for an antibiotic is the mouse protection test - simply testing whether the drug will protect a mouse against an inoculation of virulent microbes. Almost every vaccine used by humans had to be first tested on animals to ensure that it would be safe and effective. Insulin, which has saved millions of diabetics from an early and painful death was discovered through research on dogs and, until relatively recently, the only way to test for insulin during the purification process was to inject it into mice and monitor the effect on their blood sugar. Lithium, one of our most successful pharmaceuticals for mental illness, was originally discovered by a researcher who observed its calming effect on animals. Veterinary medicine owes an even greater debt to animal experimentation. Obviously, all veterinary treatments, prophylactic measures and diagnostic techniques have to be tested in animals.
Whilst there are some who clearly regard any use of animals in experiments as controversial, there is little realistic argument about the critical role that animal studies have played in medical progress. Specific advances in medicine are based upon an understanding of the biology of the body system affected. This understanding is the result of an enormous mountain of fundamental research produced over many centuries. For instance, we would never have been able to develop treatments for high blood pressure without the discovery by William Harvey of the pumping of blood by the heart around our veins and arteries. In his historic "De Motu Cordis" published in 1628, Harvey refers to work on over 30 animal species including man and all this has led to our present understanding of the physiological basis of blood pressure control. Crucially, the same biological principles arc shared across many different species. Animals that are billions of years older than man in evolutionary terms, such as the limulus crab, share fundamental similarities in their biology and physiology.
Many important advances in fundamental medical research, including the discovery of vitamins, the immune system and the endocrine system, have been the result of work on animals.
Animal experimentation also plays a vital role in applied medical research. All new medical treatments have to be tested on human volunteers before they can be licensed for medical use. However, ethical considerations place substantial limits on the ways in which human subjects can be used in such testing. Before giving a potential new medicine to a human volunteer, we must be confident that it will not cause them any harm and that it is likely to be an effective way of treating the disease in question. These two tests of safety and efficacy are the basis of developing new medicines. The only way to be confident that a new medicine is likely to be both safe and effective is to understand how that medicine behaves in a living system. That understanding can only be obtained from animal studies.
Laboratory animal research has its limitations - such work only provides models for the human patient - but they are much better models than any non-living system. Currently, the available treatments for rheumatoid arthritis do not affect the underlying pathology of the condition. Whilst they may be effective against the symptoms, they do not modify the disease process itself. To develop such new medicines, we first need to understand the pathology of the disease, a complex, long-term interaction of the immune system and cartilage growth and degeneration. This cannot be modelled in non-living systems. Even the most sophisticated tissue culture systems do not begin to reproduce these multiple interactions, which can only be observed in the living animal. There are several animal models of rheumatoid arthritis and they have revealed much important information about the cause of this condition.
Whilst arthritis is a very painful condition with severe effects on quality of life, it is rarely fatal. Cardiovascular disease, on the other hand, remains the most common cause of death for almost all of the developed world. Coronary heart disease often affects men and women in their most productive period of life, when they are working and raising a family. There is ample evidence to show that coronary heart disease builds up over decades. If we could develop a treatment to prevent this happening, hundreds of thousands of lives could be saved each year. Once again, living animal provide the best models to study this condition.
There are many other serious diseases which we cannot yet treat adequately: AIDS, Alzheimer's, multiple sclerosis, many cancers and inherited diseases such as muscular dystrophy and cystic fibrosis. They produce a huge burden of suffering, diminished quality of life, dependence on others and death. The history of medicine shows that by directing medical research at the cause of the disease we can understand the process better and develop effective treatments. There is every reason to believe that the same holds true of the diseases we now face. However, if we are going to address these diseases and develop the treatments, we will need to be able to use all the available research methods, including studies on animals. They continue to form an essential part of medical research and testing.
