I don't know about you, but I live in a world full of shit humans.
Then remove yourself. Tom, you seem to have a very human(e) perspective on the work you do, and it seems that you don't like being involved. I am not a person who whittles things down to black and white; however, it would seem to me that in this case the answer is clear. Remove yourself from that work. I'm sure it's not easy, and I don't know your life circumstances, but yes, what you feel is correct - the amount of suffering caused by using animals in medical (or other) research is one of the greatest blights on humanity in this day and age.
Death is natural and ultimately unavoidable. There will always be diseases which cause suffering and take life. There is no justification - none whatsoever - in taking any living creature, and systemically torturing it.
I find it perplexing and disturbing how often I hear people comment that testing on <insert any creature> is better than testing on humans. On what authority can people claim one life form to be 'worth' more or less than any other? Humans seem to have a severe case of superiority complex and see the Earth and its creatures as simply here for our use - as our slaves.
Most people would be sickened to know, let alone see, what goes on in medical testing facilities, and if the context of the facility was removed, and a man in normal clothes was cutting the legs off a dog in the street - do you think people would find that acceptable? And yet, in a different context people see it as "necessary".
The human population is expanding, and we want to remove anything that stops it. Becuase.... ? Why? What are we doing here? We're merely making the Earth a living hell at this rate.