I know someone personally that worked in an animal laboratory. They asked if they could console a terrified monkey and were told no. It breaks my heart. There is no reason that we need to subject sentient beings to repetitive and horrific experiments. The scientists seem to be hardened and lack any empathy towards the animals that are unwittingly put through bizzare experiments. There are plenty of humans that would be willing to be a guinea pig for experiments, especially a the end of their life. There are also ways to simulate these experiments without torturing beings.