Myths and facts

All mammals are descended from common ancestors, so humans are biologically very similar to other mammals. All mammals, including humans, have the same organs – heart, lungs, kidneys, liver etc – that work in the same way, controlled via the bloodstream and nervous system.

Of course there are minor differences, but these are far outweighed by the remarkable similarities. The differences can also give important clues about diseases and how they might be treated – for instance, if we knew why the mouse with muscular dystrophy suffers less muscle wasting than human patients, this might lead to a treatment for this debilitating and fatal disorder.

Vitamins work in the same way in animals as they do in people – research on guinea pigs led to the discovery of how vitamin C works. Hormones found in animals also work in a similar way in people. The following animal hormones have all been used successfully in human patients: insulin from pigs or cows; thyrotropin from cows; calcitonin from salmon; adrenocorticotrophic hormone from farm animals; oxytocin and vasopressin from pigs.

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• Veterinary medicine
• Animal health
• A to Z of different animals used

In fact many veterinary medicines are the same as those used for human patients: examples include antibiotics, pain killers and tranquillisers. Many of the veterinary medicines that are used to treat animals are the same as, or very similar to, those used to treat human patients.

Most human diseases exist in at least one other species. Many different animals naturally get illnesses such as cancer, heart failure, asthma, rabies and malaria and they can be treated in much the same way as human patients. There is evidence that dinosaurs suffered from arthritis. Chimpanzees can get polio and the human vaccine has been used to protect them in the wild.

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Medicines are only tested on animals after extensive screening by computer and test tube methods. Animal tests show how the medicine reacts in the living body and detect toxic effects before it is given to human volunteers.

Problems that will not be revealed by test tube results will often show up in animal tests. For instance, a medicine given by mouth may be altered by digestion, becoming less effective or more toxic. The animal tests aim to reveal major undesirable effects such as liver damage, raised blood pressure, nerve damage, or damage to the fetus. The results will give a strong indication of what the effects in people are likely to be. It is obviously important, and is required by law, to find out about potential problems before medicines are given to human volunteers and patients in clinical trials.

The new medicine will be tested on around 15 times as many human volunteers as animals. Human clinical trials will involve testing a potential drug on 3-5,000 human volunteers and patients. If a side effect (affecting say 1 in 10,000 patients) shows up only after this stage, then it is difficult to see how it could have been spotted before.

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• Where do medicines come from?
• Development of new treatments

A common myth is that penicillin is toxic to guinea pigs. It is only toxic at very high doses (a similar effect to long-term penicillin use in human patients). Like many other medicines, at equivalent doses to those used to treat people, it is not toxic.

Another common myth is that thalidomide didn’t cause birth defects in animals. In fact it wasn’t tested in pregnant animals before it was prescribed to pregnant women. As soon as the tragic effects on unborn babies came to light, testing of thalidomide on pregnant animals showed it had very similar effects in many species. This led directly to the introduction of the UK Medicines Act in 1968.

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• Penicillin protects mice against infection
• Regulation

Only around 4 in every 100 medicines are withdrawn after their launch because of side effects which were undetected during both human and animal tests. Of the 2,000 types of medicine on the market, since 1961 only about 40 have been withdrawn in the UK, US, France or Germany due to serious side effects. This indicates a success rate of at least 98% for medicines testing. Only 10 of the 40 medicines withdrawn have been withdrawn in all four countries.

Numbers of drug induced deaths or hospitalisation due to side effects are often exaggerated or misleading. Most of these deaths are not caused by normal doses of drugs, but are in fact due to accidental or deliberate overdose.

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• Development of new treatments
• Safety testing

Vioxx was extensively studied in thousands of human patients, both before and after it was approved by over 70 regulatory agencies around the world. For any new medicine, animal and other tests are meant to help work out if the medicine is safe enough for human trials. In the case of Vioxx, the answer was yes – animal tests did their job well.

Only when over 80 million patients around the world had taken this medicine and some long-term patient studies had been conducted was the increased risk of heart attack firmly established.

One answer to the problem of rare drug side effects is better scrutiny after approval. This would help to predict which patients might react badly – because of their genetic make-up, multiple illnesses or interactions with other medication.

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• Safety testing
• The research process

The discovery of insulin in dogs in the 1920s by Banting and Best is a good example of the contribution of animal research to medical progress. Before the discovery of insulin, there was no effective treatment for the disease and people with diabetes usually died tragically young. Diabetic dogs have also benefited from insulin treatment.

Each decade since the discovery of insulin has seen the introduction of new kinds of treatments for many diseases. Each of these and many other advances were critically dependent on animal research.

Given continued research using animals, we can expect further advances in the treatment of diseases such as Alzheimer’s disease, cancer, cystic fibrosis and crippling joint disease. It is very difficult to see how we could make such medical advances without animal research.

Four independent reports have found that animal studies make an important contribution to scientific and medical advances.

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• Medical advances timeline
• Expert and independent opinion

TGN1412 is one of the newer ‘biological’ medicines. None of the tests done before the clinical trial predicted its tragic side-effects. The expert inquiry described the human blood cell tests as a 'striking failure', and the clinical trial itself was poorly designed. Testing the safety and effectiveness of such treatments is more difficult than most medicines, but many biologicals which have been developed in animals, like Herceptin, are already saving lives.

There are around 300 clinical trials every year in the UK. Yet the kind of problem seen at Northwick Park Hospital is very rare, partly because animal and other tests are so good at discovering problems. To suggest that we abandon some tests because they are not 100% perfect is like saying that we should stop wearing seatbelts because they do not prevent all injuries.

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• Breast cancer treatment

HIV has been difficult to tackle because the virus fools the body’s immune system. It is true that we do not yet have an effective vaccine. Some leading researchers are now suggesting that more basic research should be done before trialling vaccines in patients – which does remain the ultimate goal of research.

However, animal studies were crucial in identifying the virus, for developing diagnostic tests, and for producing therapies such as antiretrovirals that have prolonged millions of lives. These medicines mean that HIV can be a manageable chronic condition rather than an automatic death sentence, as it was in the 1980s.

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• HIV & AIDS
• Research using monkeys

Systematic reviews can help to tell us whether studies are being properly carried out and published. For example, a systematic review in the respected medical journal The Lancetshowed that none of the 500 human clinical trials for an illness called tardive dyskinesia produced any useful data.

Systematic reviews have shown that all types of study can be improved. Where they have been carried out, systematic reviews and other independent studies have shown that animal studies can be relevant for human medical advances.

However, systematic reviews simply cannot provide all the answers. A lot depends on how studies are selected for review. For most animal research, the aim is not to predict what will happen in human trials, but to discover new knowledge or make advances in understanding diseases. In many cases comparing the results of animal research and results from human trials is as meaningless as comparing apples and oranges.

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• Systematic reviews in animal research

We cannot yet reproduce complex diseases in a cell culture, get a computer to cough, or examine a whole beating heart in a test-tube. By law, animals must not be used in a research project if viable non-animal techniques are available.

Most research is already carried out using these other methods. But we still need to use animals at some point. The living body is much more than just a collection of its parts; we need to understand how they interact. Humans can only be used in limited situations.

Scientists have strong ethical, economic and legal obligations to use animals in research only when necessary. As science progresses, it may be possible to reduce further the numbers of animals used in some areas. In other areas, the numbers of animals may increase.

The guiding principles in animal research today are called the three Rs: Refinement, to make sure animals suffer as little as possible; Reduction, to minimise the number of animals used; Replacement, to replace animals with non-animal techniques wherever possible;

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• Replacement
• Numbers of animals
• Three Rs

Functional MRI (fMRI) measures blood flow in different parts of the brain. It can be used in human volunteers without ill effect. But it does not give anything like the same level of detailed information that can be achieved by painlessly inserting electrodes into brain tissue in animal or human studies.

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• The need for research on non-human primates in cognitive neuroscience
• Alternatives and replacements

Microdosing is used to study how very small doses of potential medicines behave in human volunteers (sometimes called Phase 0 human trials). It should make the drug discovery process more efficient by highlighting earlier whether a compound is effective. New, urgently needed medicines could be available sooner and more cheaply as a result.

If microdosing shows that certain potential medicines are not suitable, it should reduce the number of animals used because these compounds would not need to be further developed and tested. But compounds that look promising would need to go through development and testing involving animals.

Microdosing has limitations like any other method of testing. There is no guarantee that the body's reaction to a microdose will be the same as it is to a full dose. It is a relatively new method and has yet to be fully validated, although it looks promising.

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• The research process - microdosing
• Alternatives

Improvements such as clean water and good sanitation were responsible for a dramatic drop in the great water-borne infectious diseases of the nineteenth century. However, by the 1940s and 50s, when clean water and good sanitation were standard in the UK, there were still hundreds of thousands of cases of these often fatal diseases every year.

Vaccines have virtually eradicated some ‘old’ diseases like TB, diphtheria and cholera in developed countries. Recent vaccination programmes, such has meningitis and MMR, have greatly reduced childhood infections. When vaccination is not taken up by a good majority the number of cases, of measles for instance, rises.

Smallpox was eradicated thanks largely to a worldwide vaccination programme and the World Health Organisation aims to eliminate polio worldwide by immunisation. Newer diseases such as HIV and many tropical diseases such as malaria will only be effectively tackled by vaccines.

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• Meningitis vaccine
• Polio vaccine
• HIV and AIDS

Unnecessary animal experiments are very unlikely in the UK for the following reasons:

• The strict controls on animal research, in the Animals (Scientific Procedures) Act 1986, do not allow animals to be used to obtain information that is obtainable by other means.

• Research using animals is very expensive because the animals are costly to buy or breed, to house, and to care for, and the work itself is slow and labour intensive.

• Funds for biomedical research are limited, so each research proposal is rigorously assessed by panels of experts. Trivial, irrelevant or repetitive work will not attract funding.

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Associated Links:

• Regulation
• Animal welfare and the three Rs

If researchers were motivated by the desire for profit, rather than the desire to establish scientific fact, then animal experimentation is the last technique they would adopt, since it is much more expensive than other, non-animal methods.

The high cost is largely due to the number of staff required to look after the animals’ welfare. Vets are on call 24/7 and all animal technicians must have months of specific training to look after the animals.

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• Regulation
• Animal welfare and the three Rs

More than 80 out of every 100 animals used in research are mice, rats and other rodents. Only one in every 1,000 research animals is a cat or a dog.

Dogs, because of the size and similarity of their organs, are important for the development of new surgical techniques and for the study of the heart, lungs and blood vessels. Cats are important in the study of hearing and brain function. The use of both cats and dogs is subject to particular controls which require that they are specially bred for research. Stray cats and dogs or lost pets are not used for research in Britain.

Some people believe that monkeys and apes (primates) are used in great numbers, but monkeys represent less than one in every 2,000 research animals. Apes are not used at all in the UK and Europe. Smaller primates such as macaques and marmosets are needed for research into very serious conditions such as AIDS and Alzheimer's disease.

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• Types of animals
• Medical advances timeline

Around the world the welfare of animals in research is protected by national and international legislation, by local laws or by ethical committees. The UK is widely recognised as having some of the most comprehensive regulations covering laboratory animal welfare. Uniquely, UK researchers must both comply with stringent national regulations and submit their research proposals to local ethical review.

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• Regulation

Researchers are concerned about the welfare of the animals that they study and this concern is both humane and scientific. Scientists are at least as caring as other people and, like anyone else, often have pets of their own. They have no reason to mistreat research animals and good reason for treating them well, because the use of unhealthy, stressed or frightened animals would reduce the reliability of an experiment’s results. Researchers make sure that their animals are well fed, well housed and kept free of infections and other illnesses.

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• Refinement

By law, researchers must work to minimise the suffering of animals in laboratories. This might be by using analgesia or anaesthesia to alleviate pain during or after a procedure, or it could be providing enrichment for animals in order to encourage mental stimulation and prevent boredom. 98% of procedures are classified as sub-threshold, mild or moderate.

It is in researchers’ interests to make sure animals suffer as little as possible; stressed animals are less likely to produce reliable results. All animal research must pass an ethical evaluation which weighs up its pros and cons and decides whether it is justified. The research then has to be approved by Home Office Inspectors, who are all doctors or vets and who ensure that high welfare standards are applied.

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• Animal welfare
• Regulation

Testing of cosmetics and cosmetic ingredients on animals has been banned in the UK since 1998. A Europe-wide ban is scheduled to come into force in 2010.

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• Areas of research