Third in a series on animal experimentation, this article looks at some of the ways in which animals are used in medical research.
Scientific experiments involving animals can be classified into several different categories, including: pure research, applied research, toxicology, and drug testing.
Pure (Basic) Research
Pure research is an examination of organisms at a fairly broad level: how they develop, function, and behave. This type of research tends to use animals of a wide range – from fruit flies to rodents to sea slugs. Opponents of animal testing argue that this type of research is not of any practical use; however researchers say that pure research can produce benefits which simply can’t be predicted, and that adding to our store of knowledge is never useless.
Examples include behavioral experiments, breeding experiments which study genetics and evolution, and studies which explore developmental aspects of certain organisms – such as the effects of genetic changes during embryogenesis or fetal development.
Unlike pure research, which is more knowledge for its own sake, applied research is carried out for the purpose of finding answers to specific questions, and solving specific problems. In general, applied research is more likely to be carried out for commercial purposes than is pure research.
One very commonly-used example of applied research is the genetic modification of animals to examine specific diseases. Genes may be inserted, removed, or modified, to cause the animal to exhibit symptoms which mimic a certain disease. Such an approach allows researchers to examine the cause and development of the disease, and provides a medium for testing treatments.
Toxicology tests are generally carried out by drug companies which test the drugs they make, and by testing facilities which carry out contracted tests on behalf of other companies (an example of such a facility is Huntingdon Life Sciences, with laboratories in several countries).
This type of testing is not only carried out to determine the toxicity of pharmaceuticals – pesticides, food additives, cosmetics, air fresheners, and in fact almost any synthetic substance may be tested for toxic effects.
The testing of cosmetics is a particularly controversial subject, all over the world. These types of tests typically involve testing toxicity on the skin and eyes, and are considered by many to be unnecessary. A long list of cosmetic companies has developed cruelty-free products to meet consumer demand.
All new drugs must undergo several phases of animal testing before they can be trialed in humans. Several types of tests are carried out.
Metabolic tests – these investigate how drugs are absorbed, metabolized, and excreted. Often, several methods of delivery are tested.
Toxicology tests – determine toxic and sub-toxic levels of the drug in animals, and determine whether toxic levels of the drug or metabolites can accumulate over time.
Efficacy tests – simply test whether the drug works as intended. The disease is induced in experimental animals, which are then treated with the drug.
- Depending on the drug involved, and the law, other studies, such as embryonic toxicity, reproductive function, and carcinogenic potential tests may be required.