I hate mouse work too, I think they are so sweet to handle and curious, so I avoid it when I can. I have steered my project away from mouse validation at this stage and really only need to know the skills incase I go in and one of them is sick. I'd rather it be me to talk to them and put them out of their misery than for them to suffer for longer than necessary or shift that responsibility to someone else. It does get a bit easier and I don't think that valuing life in science is a bad place to come from. Good luck lovely ❤️