I have a friend who raises mice and then has to break their necks to euthanize them before experimenting on them. Another of my friends has to give mice cancer.
The former friend's lab has come up with life-changing treatments for muscular diseases, and the latter friend is helping to develop immunotherapy methods.
While it's awful to think about the price, it's important to think about why the price is paid and how much suffering can be prevented.
Another note: there are strict codes of ethics for how animals are treated in labs, so in most reputable organizations, the suffering is as minimal as possible (sometimes no suffering at all).