Animals have played a significant role in almost every major medical advance in the last century. If it was not for the incredible role of animals in biomedical research, many lifesaving therapies for humans and animals would not exist today.
Specific details regarding the contributions animals have made to biomedical research are available here:
Scientists today are closer than ever to finding new preventions, therapies, and cures for countless diseases shared by humans and animals.
Advances in tissue engineering and software development are providing more and more alternatives to various medical experiments. In vitro testing, using cell and tissue based models, is a very important aspect of medical research. In silico testing, or computer models, are also providing important tools for understanding biology and the mechanisms of disease. New technology is allowing scientists to use fewer animals in their experiments while still gaining the same amount of knowledge. However, animals are still needed for some studies. Unfortunately, scientists still cannot determine the full extent of how safe new medicines or medical devices are, nor how well they work, just from cells, tissues or computer simulations alone at this point in time.
As of yet, there is no complete alternative to biomedical research with animals, and laboratory animals continue to provide a great service to the advancement of medical discoveries.