Almost every form of conventional medical treatment (including most drugs, surgical treatments, and vaccines) was developed with the help of animal research. Most of what we know about the basic workings of the body—in humans and animals—has come to us through two centuries of animal experiments. Each decade of animal research has brought newer and deeper understanding.
from this BMJ review. Inexplicably, BMJ, which used to be free full access, has lots of content, such as this, available only to subscribers. I guess too few people were subscribing to the journal. Kind of puts all their editorials decrying the profit motive in healthcare in a new light.
UPDATE: fixed title