Does animal testing work?

Level: Intermediate

Animal Experiments

Key Points

• More than 2.7 million live animal experiments were authorised in Great Britain in 2002. This number has halved in the last 30 years
• Around the world, animals are used to test products ranging from shampoo to new cancer drugs
• British law requires that any new drug must be tested on at least two different species of live mammal. One must be a large non-rodent
• UK regulations are considered some of the most rigorous in the world - the Animals Act of 1986 insists that no animal experiments be conducted if there is a realistic alternative

Almost every medical treatment you use has been tested on animals. Animals were also used to develop anesthetics to prevent human pain and suffering during surgery.

It is estimated that 50 million–100 million animals worldwide are used annually and subsequently killed in scientific procedures — conducted as part of pure research, applied research, or toxicology testing — mostly inside universities, medical schools, pharmaceutical companies, and commercial facilities that provide animal-testing services to industry. Testing is also carried out on farms, in defense-research establishments, and by public-health authorities, on a variety of species from fruit flies and mice to non-human primates. Most laboratory animals are purpose bred, while a smaller number are caught in the wild or supplied by pounds.

The topic is controversial, with supporters and opponents arguing about ethical issues and whether using animal models is good or bad science. According to the U.S. Foundation for Biomedical Research, "animal research has played a vital role in virtually every major medical advance of the last century — for both human and animal health." The foundation, in addition to various other groups and former Nobel Prize recipients, agree that many major developments that led to Nobel Prizes critically depended on animal research, including the development of penicillin (mice), organ transplant (dogs), and work on poliomyelitis that led to a vaccine (mice, monkeys). Whether animal research was necessary to achieve these results has been questioned by animal rights groups and critics of the animal model.

The moral basis of the pro-testing position was summarized by a British House of Lords report in 2002: "The institution of morality, society, and law is founded on the belief that human beings are unique amongst animals," and are therefore morally entitled to use them for their own purposes. This belief is "combined with a further belief that there is a moral imperative ... to develop medical and veterinary science for the relief of suffering ..." Some people also believe that animals may suffer less during experiments than human beings would, arguing that although all mammals have similar pain receptors and central nervous system pathways and may feel physical pain in the same way, non-human mammals suffer less because they have a reduced capacity to remember and to anticipate pain. Opponents of animal testing strongly contest these views.

History

The earliest references to animal testing are found in the writings of the Greeks in the third and fourth centuries BCE, with Aristotle (384-322 BCE) and Erasistratus (304-258 BCE) among the first to perform experiments on living animals (Cohen and Loew 1984). Galen, a physician in second-century Rome, dissected pigs and goats, and is known as the "father of vivisection."

Animals have played a role in numerous well-known experiments. In 1796, Edward Jenner extracted pus from pox-infected cows to inoculate James Phipps against smallpox. The virus was the top cause of mortality in England before Jenner's work. In the 1880s, Louis Pasteur convincingly demonstrated the germ theory of medicine by giving anthrax to sheep. In the 1890s, Ivan Pavlov famously used dogs to describe classical conditioning. Insulin was isolated first from dogs in 1922, and revolutionized the treatment of diabetes. On November 3, 1957 a Russian dog named Laika became the first of many animals to orbit the earth. In the 1970s, leprosy multi-drug antibiotic treatments were developed first in armadillos, then in humans. In 1996 Dolly the sheep was born, the first mammal to be cloned from an adult cell.

In 1822, in the British parliament, Richard Martin MP piloted the first parliamentary bill in the world to give animals a degree of protection through the law. This first bill related to farm animals. The first to regulate animal experimentation in Britain was the Cruelty to Animals Act (1876). One of the people who campaigned to see the bill introduced was Charles Darwin (1809-1882). He said, in a letter of March 22, 1871 to Professor Ray Lankester: "You ask about my opinion on vivisection. I quite agree that it is justifiable for real investigations on physiology; but not for mere damnable and detestable curiosity. It is a subject which makes me sick with horror, so I will not say another word about it; else I shall not sleep to-night." The bill remained on the statute books until the introduction of the Animals (Scientific Procedures) Act (1986).

From the early days of animal welfare legislation concerns were both for the relief of animal suffering and also for the moral health of humanity. The Victorians were particularly concerned that people should show good moral virtues such as kindness and concern for others. It was in Victorian Britain that the RSPCA (the world's first SPCA - Society for the Prevention of Cruelty to Animals) was formed. One of the founder members was William Wilberforce, who was also in the forefront of anti-slavery activism.

These Victorian concerns have formed a backdrop to ongoing debate throughout the 20th century and into current times.

The defenders of animal testing believe the differences between species to be very minor and not sufficient to invalidate the results obtained. They also say that cures for many illnesses have been found by the use of animal experiments. These claims are disputed.

The argument is often raised that animals themselves benefit from being experimented upon since these experiments can lead to veterinary medicines and procedures. There is also a strong moral and emotional feeling that even one single medical advance for humans is worth any number of animals.

Focusing on the cruelty issues, SPCAs have been formed in Canada, Australia, New Zealand, The United States and other countries. Animal welfare organisations have fiercely debated the issues both scientific and moral and have developed an offshoot: the animal rights movement.

Focusing on the scientific issues, research departments have been set up in Europe and the USA to find as many non-animal methods of research as possible and to provide the information about these methods to scientists working within relevant fields.

Species

Invertebrates

Most of the animals used in animal testing are invertebrates, especially Drosophila melanogaster, a fruit fly, and Caenorhabditis elegans, a nematode. In the case of C. elegans, the precise lineage of all of the organism's cells is known, and D. melanogaster has various characteristics making it well suited to genetic studies.

Rodents

Rats and mice, the most commonly utilized vertebrate species, are used in large proportion because they are small, inexpensive, easy to handle and care for, and can produce up to 100 pups in a year. Mice are considered the prime model of inherited human disease, are genetically tractable and share 99% of their genes with humans.

Fish and amphibia

In the UK, 194,562 fish and 18,195 amphibia were used in 2004. The major species utilized are the zebrafish, Danio rerio, which are translucent during their embryonic stage, and the African clawed frog, Xenopus laevis.

Rabbits

Over 20,000 rabbits were used for animal testing in the UK in 2004. Albino rabbits are used in eye irritancy tests because rabbits have less tear flow than other animals and the lack of eye pigment make the effects easier to visualize. They are also used in skin irritancy tests. In 2004 less than 12% of the rabbits were used for safety testing of non-medical products.

Dogs

Beagles are used, because they are friendly and gentle, in toxicity tests, surgery, and dental experiments. Toxicology tests are required to last six months in the UK, although British laboratories carry out tests lasting nine months on behalf of Japanese and American customers. Of the 8,018 dogs used in the UK in 2004, 7,799 were beagles (97.3%). In the UK, most dogs are bred for the purpose, for example by Harlan in Leicestershire.

Non-human primates (NHPs)

Most of the NHPs used are baboons, macaques, marmosets, and chimpanzees. Licenses approving the use of non-human great apes, such as gorillas, chimpanzees, and orangutans are not currently being issued in Britain, though their use has not been outlawed, but chimpanzees are used in the U.S., with an estimated 1,300 still remaining in research laboratories.

Cats

Felines are most commonly used in neurological research. In the UK, 819 cats were used in 2004. According to the USDA(United States Department of Agriculture), over 25,500 felines were used in the USA in 2000, of these around half were reported to have been used in experiments that caused "pain and/or distress".

Does animal testing work?

The 'Three Rs'
In 1959, British zoologist William M. S. Russell and microbiologist Rex L. Burch published "The Principles of Humane Experimental Technique", in which they put forth the 'three Rs of animal research':

Replacement - use alternative methods, e.g. testing on cell cultures (in vitro)

Reduction - use statistics to reduce the number of animals that must be used for each experiment

Refinement - improve the experiment to reduce animal suffering

Animal welfare groups are divided in their position on the 'three Rs'; some support the principles while others accept replacement as the only valid action. There are a number of scientific studies and institutes researching alternatives to animal tests. However, critics say these facilities perpetuate the myth that animal experiments are necessary for human health, and to reassure the public that steps are being taken to find alternatives. It is further stated these studies are funded with trivial amounts of money, but this view is contested by the UK pharmaceutical industry, which estimates more than £300 million (of a total UK R&D budget of £3285 million) is spent on 'three R' development and implementation annually.

Paying for alternatives
Humanitarian organisations and governments have funded studies into alternative methods since the 1960s. For the past 15 years, Germany has given Ј4.2 million a year in research grants, while the Netherlands spends Ј1.4 million a year. It is estimated that the total spent by the UK government is in the region of Ј2 million a year. The European Centre for the Validation of Alternative Methods was set up in 1992 by the European Commission, and contributes Ј6.3 million annually. EU regulations state that researchers must assess the pain that an animal may feel during an experiment, and justify its suffering by what the research can achieve.

Reducing deaths...
In the past, the toxicity of a new substance was measured by an 'LD50' (lethal dose 50%) test. This test required up to 200 rats, dogs or other animals to be force-fed different amounts of the substance, to determine the dose that would kill exactly half that group of animals.

Recent changes in protocol have put a ban on the LD50 test, save in exceptional circumstances. In addition, the Organisation for Economic Co-operation and Development says that if a substance kills the first three animals it is tested on, further trials are unnecessary.

...by using statistics
A vaccine is only considered effective if at least 80% of the vaccinated animals survive after being exposed to a particular disease. However, the disease must also kill 80% of a control group not protected by the vaccine. Using statistical methods, Coenraad Hendriksen of the National Institute of Public Health and the Environment in the Netherlands has developed a method to test diphtheria and tetanus vaccines that only requires measuring the level of antibodies in an animal.

Apart from greatly reducing their suffering, it also uses half the number of animals. Other statistical techniques can use patient data to understand how a disease spreads, without testing it on animals.

...using fewer mammals
Horst Spielmann of ZEBET, the German centre for animal testing alternatives, has surveyed decades of industry data on pesticides. He concluded that if mice and rats prove sensitive to a chemical, it does not have to undergo further tests on dogs. Spielmann anticipates that 70% of dog tests can now be dispensed with.

There is a general effort by researchers to use lab animals that are less likely to suffer the sensations of pain or discomfort. In Canada, many studies have replaced mammals with fish, and now researchers are even trying to use bacteria in tests instead of rats.

...using cell cultures
In the 1970s, the Netherlands used 5,000 monkeys a year to make polio vaccines. Now kidney cell cultures from just 10 monkeys provide enough vaccine for everyone in the country. Hormones or vaccines manufactured in cell cultures are also purer than those made within the animals themselves. This further reduces the need for animal tests to check the safety of the vaccines.

...using synthetic membranes
The Department of Transportation became the first US agency to accept tests for skin corrosivity conducted on artificially-grown cells in 1993. The traditional test simply measured how far a corrosive substance ate into an anaesthetised rabbit's shaved back. Instead, the replacement uses reconstructed human skin, or a synthetic material called 'Corrositex'. Similar solutions are being developed for many other types of experiments which currently use animals.

...using new technologies
New scanning technologies (such as Magnetic Resonance Imaging) can help doctors learn about disease from human patients without the need for invasive surgery, or animal testing.

Similarly, autopsies and cell culture studies can reveal a great deal of information without having to simulate the disease in a lab animal. Computer models have also been developed that simulate an animal's response, removing the need for live animal tests.

In the future
Animal researchers say that it will be impossible to eliminate all animal tests. But most scientists accept that it is extremely important to minimise the suffering of laboratory animals, and to use as few animals as possible.

Date: 2015-12-18; view: 706