The Debate About Animal Experimentation: Benefits and Controversies

Animal testing is the use of non-human animals for the purpose of scientific experimentation. Around fifty to one hundred million vertebrate animals, ranging from fish to primates, are used in experiments each year. Many more invertebrates—including flies and worms—are also used in experiments (although the use of these animals is largely unregulated).


There are many different words used to describe the practice of animal testing. In general they all mean more or less the same thing – but the words themselves tend to have different connotations for many people.

· Animal testing, experimentation, or research

· In vivo research – literally “in life,” meaning the experiment is conducted in a living organism (in vitro means “in glass,” – the use of this phrase denotes an experiment that does not involve a living organism. However it may involve living cells).

· Vivisection – this term is historically defined as the dissection (or operation on) of living animals for experimental purposes. It later came to be used as a catch-all term for all kinds of animal research; these days it is used more as a pejorative by people opposed to the use of animals in scientific experiments.

Where does Animal Research Take Place?

Animal research is conducted in a wide variety of places: within colleges and university laboratories, in medical schools, on farms, in pharmaceutical companies, and in commercial facilities which provide testing services to certain types of industry.

Many biological sciences involve the use of animals in experiments: immunology, genetics, biochemistry, behavioral psychology, biomedical research, xenotransplantation research, and toxicology (including drug and cosmetic testing).

Animal Testing Controversy

The use of animals in scientific research has been a controversial issue for some time. While supporters argue that most major medical achievements have involved the use of animals, and could not have been made otherwise, detractors of the practice say that it is cruel, unnecessary, scientifically unreliable, and both ethically and morally abhorrent.

The issue of animal testing largely revolves around ethical problems: the justification of using living animals in research to benefit humans, and the problems posed by situations where animals suffer as a result of research.

Another prominent issue is one of compatibility between species: historically, there have been situations where the failings of animal experimentation have been exposed due to differences in the way animals and humans respond to various substances. (Note, however, that the thalidomide story is not such a situation – this was more a failure of scientific design than of the use of animals, as thalidomide was never tested in any pregnant organism before its release for human use.)

Finally, there is the issue of alternatives to animal research, and whether they are viable replacements for any or all types of animal experimentation.

This post is part of the series: Animal Experimentation

A six-part series which examines practical and ethical issues involved in the use of animals for scientific research.
  1. An Introduction to the Use of Animal Experimentation in Medical Science
  2. A History of How Scientists Used Animal Testing to Make Medical Advances
  3. Animal Experimentation: Uses of Animals in Research
  4. Animal Experimentation: Practical and Ethical Issues
  5. Animal Experimentation: Alternatives to the Use of Animals in Research
  6. Animal Experimentation: Regulations for the Use of Animals in Research