Second, drugs from animal are sometimes ineffective and harmful for humans. Animals’ biology is very different from human beings. The anatomic, metabolic, and cellular of animals are so different from humans’, so the result of the test may be low-qualified, and inaccurate. The differences between animals and humans can lead to the completely different reactions. According to Paul Furlong, Professor of Clinical Neuroimaging at Aston University (UK), "it's very hard to create an animal model that even equates closely to what we're trying to achieve in the human4." For example, the Draize eye test−an acute toxicity test−is impractical to human because rabbits’ and humans’ cornea are structurally different. Rabbits’ corneas produce fewer tears, so the chemical will not be cleaned as soon as in humans’ eyes and it will cause more irritation.5
Furthermore, Drugs that pass animal tests are not always safe because the unreliably predicted result could affect the safety of humans. For instance, in 1950s, many new-born babies had to be seriously deformed because of sleeping pill thalidomide, even if it was tested the animal before it was released.6 Another example is the drug named Vioxx, a medicine developed for treating arthritis, which caused 27,000 heart attacks and sudden cardiac deaths, had passed the animal-testing also. It killed more Americans than in the Vietnam War, although it seems safe in eight studies using six different animal species.7 Ineffective drugs can be harmful to the live of mankind, so animal-testing is not a good idea.