When it comes to feeling pain, hunger, and thirst, "a mouse is a pig is a dog is a boy" (Monagle 1). In other words, animals experience pleasure and pain in much the same way as humans. And although this is one of the main goals of the fight against animal testing, it is extremely useful for the medical testing community. Because of this, we are able to very effectively see how animals react when they are given the drug. Effects such as aggressive or hostile behavior, mood changes, insomnia, involuntary tics and spasms, itching and nervousness are very common when it comes to drug use. As a result, we need to be able to use animal testing to ensure that we are not giving these drugs to humans without them knowing about these possible side effects..