Under the Microscope: Many advances in biological and biomedical research have resulted from experimentation on animals. Humans and animals have close ties and many people, including many scientists, have mixed feelings about using animals in research.
Scientists would not need to use animals in research in an ideal world, but, we live in a non-ideal world and awkward ethical questions arise. Science, Medicine and Animals (National Academies Press, 2004) is a useful discussion on the subject.
Some questions include: (a) Is it ethical to allow human and animal diseases to continue for which cures could be found through painless research on animals? (b) Is it ethical to perform painful experiments on animals where these experiments lead to cures for human disease or to new and better treatments? (c) Is it ethical to experiment on animals when new treatments resulting from these experiments might not occur for many years, if ever?
Polls indicate that a majority of people condone painless research on animals that produces treatments and cures for human disease. A minority think that such research should be carried out on humans, not on animals.
However, most people would not condone research on humans, believing that humans deserve higher moral consideration than animals.
Some anti-vivisectionists condemn biomedical research on animals on the grounds that animals are so different from humans that any results obtained cannot be successfully extrapolated to humans. This argument is wrong. Humans contract many of the same diseases as animals. For example, humans and dogs have 65 infectious diseases in common. The figure for cattle is 50, 42 for pigs, 35 for horses and 26 for fowl. We have lived among animals for thousands of years and we are susceptible to many of the same parasites, viruses and bacteria as animals and some of these can be transmitted between animals and people, eg rabies and malaria. Also, many non-infectious chronic diseases like epilepsy also afflict other species.
We are all familiar today with the concept that micro-organisms (germs) can invade the body and cause disease. This "germ theory" of disease, which led to the development of antibiotics to fight these micro-organisms and vaccines to render people immune to them, could not have happened without animal research.
Towards the end of the 19th century, Robert Koch (1843-1910) established that a particular germ caused a specific disease. He examined the blood of cows that had died of anthrax, saw rod-shaped bacteria and guessed that they caused anthrax. When Koch injected mice with blood taken from cows suffering from anthrax, the mice also developed anthrax.
Koch, Pasteur and others identified the germs causing anthrax, diphtheria, rabies and the plague. These discoveries allowed scientists to develop vaccines for animals and people by using weakened germs.
A vaccine against anthrax was one of the first to be developed. Louis Pasteur (1822-1895) weakened anthrax bacteria by heating so that it no longer caused disease and vaccinated a group of sheep with the weakened bacteria, causing the sheep's immune systems to produce antibodies against them. Pasteur later infected this vaccinated group and another non-vaccinated group with live anthrax. The vaccinated group all survived whereas the non-vaccinated group died. The vaccinated animals' immune systems fought the live anthrax and thus prevented the disease. The anthrax vaccine has saved many farm animals and people from death by anthrax.
Until the 20th century, smallpox, polio, diphtheria, tetanus, whooping cough, measles, and mumps deformed and killed thousands of children a year. But with the development of vaccines, natural smallpox has been eradicated from the world since 1977, polio has been eradicated in the western hemisphere, and whooping cough, tetanus and mumps are rarely seen in developed countries.
Many life-saving surgical procedures, including organ transplantation, heart valve replacement, coronary artery bypass and open-heart surgery, have been developed using animal models first. Animal studies have also led to the development of drugs to treat epilepsy and certain forms of cancer.
Animals are considered essential for testing the safety of food additives, drugs, workplace chemicals, vaccines and so on. Animals have also been used extensively to test cosmetic products, but the EU has agreed to implement a Europe-wide ban on animal use to test cosmetics by 2009.
Nobody with a shred of sensitivity could be unbothered by using animals for the various purposes that I have described and, so, there is a drive on to produce alternatives to animal experimentation. For example, much testing and research can be done by computer modelling or using cells grown in tissue culture. Use of animals in research has been significantly reduced in recent decades and this decline will accelerate in the future. However some questions can be answered only by experimenting on animals.
Take safety testing a new drug for example. Cell cultures and computer models can be used to screen and test the toxic potential of a new substance in the early stages of investigation, thereby sparing the use of animals.
The final test, however, must be done in a whole living system. Even the most sophisticated alternative methods cannot mimic the complicated interactions that occur between cells, tissues and organs in humans and animals.
We must reduce the use of animals in biomedical research to the absolute minimum. However, at the moment our best hopes for developing treatments and cures for diseases such as Alzheimer's, Aids and cancer involve research using animals.
The use of animals in such work is a privilege that must be used sparingly and humanely, while at the same time trying hard to develop alternative methods that will eventually make animal experiments unnecessary.
• William Reville is associate professor of biochemistry and director of microscopy at UCC - http://understandingscience.ucc.ie