|MadSci Network: Medicine|
Scientists use animals to test medicines and other substances for a variety of reasons that primarily boil down to whether these substances are suitable for use. I purposely did not include the words "in humans" because medicines for pets & livestock are also tested in animals. Safety is the primary concern, for example whether the substance can kill you, cause cancer or damage the liver. For vaccines there is the additional need to know if the vaccine will protect animals against the disease. For some substances there is the ability to do tests that do not involve animals, but at this time our knowledge of biology is such that it is impossible to use simple cell culture tests or computer models to predict exactly what will happen for most substances when they are given to a person or animal. Animal testing is currently the best means of assessing the safety of a substance. But animal testing is not perfect - a good scientist will make a careful determination whether the animal they have chosen for testing is a good one.