I have euthansied one mouse before and it was horrific so I can’t imagine what you have to go through for research. I have been present for many euthansia’s I’ll never forget my first one which was a wallaby that had a condition called lumpy jaw. He was sedated first then after trying to find a large vein for a while the vet finally put him to rest, completely heartbreaking. At least if the experiment goes wrong you can put the animal out of pain as quickly as possible. Thanks for sharing an insight to your life :)