Research involving animals has been a cornerstone of medical progress for more than two centuries. For most of that time, it has also met with moral objections because of the suffering it can cause the animals. Though animal welfare laws in the United States and other countries have reduced the number of laboratory animals and ameliorated their pain, ethical concerns remain.

How can the number of animals used for experimentation – estimated to be 100 million animals internationally each year – be reduced without reducing the quality of research? Do some types of animals have higher moral status than others and, if so, is it ethically desirable to replace a “higher” species with a lower one in research? What constitutes humane treatment of the animals and how can that be improved? What more can be done to develop alternatives to animal models?