If you ever need to euthanize a few individual mice, even pinks/fuzzies, get a bottle of canned air. It kills them very quickly(they may agonal breathe for a bit, but that's normal) and they do not suffer. I have euthanized my pet rats at home when I can't get them in to see the vet this way. They go very peacefully.
+1
Ive had a Very sick looking mouse than I did not want around my colony, so I just got done doing this. She was dead in a matter of seconds and she seemed to go peacefully.
- Matt
Come here little guy. You're awfully cute and fluffy but unfortunately for you, you're made of meat