Considerable evidence demonstrates that animal experimentation is inefficient, unreliable and unsafe. It is also unnecessary because newly developed methodologies are more valid and less expensive than animal studies. An increasing number of doctors and scientists agree that the methodology of today's biomedical research is invalid and counterproductive. Many times the unreliability of animal research has produced highly unpredicted and unwanted results. The danger and varying reliability of animal experimentation stems from the fact that vivisection (live animal experimentation) research entails gathering data on animals with artificially induced versions of human diseases in place of information on humans with the actual diseases. This is nearly useless because not only is every species bio-mechanically and bio-chemically different but laboratory results are further skewed by the stressful and unnaturally living environments of the test subjects. In addition the researchers involved in vivisection are often said to overshadow its negative aspects. Although vivisection supporters claim that it has played a crucial role in virtually all medical advances. Several medical historians argue that key discoveries in such areas as heart disease, cancer, immunology, and anesthesia, were in fact achieved through clinical research, observation of patients, and human autopsy. In addition in vitro cell and tissue cultures have proven to be powerful investigative tools. .
Animal Research has proven on many accounts to be highly unsafe. It is dangerous because drugs tested safe and effective on animals often prove not to be so during human guinea pig testing. The drug Milrinone increased the survival of rats with artificially induced heart failure, but there was a 30% increase in the mortality rate of humans taking the drug. A drug, which appeared safe in animal tests, Fialuridine, caused liver failure in 7 of 15 humans taking the drug; five died and two required liver transplants.