Awww, poor baby
I'm sorry that he's hurt, but glad that he's found someone to love him.
I don't have any experience with a severely injured Yorkie, but I imagine that you could just use baby wipes on him if you are afraid to bathe him. He'll guide you on what's comfortable for him as far as holding him or picking him up. If you can, talk to the vet about this stuff so they can show you how to handle him.
Do you know what happened to the poor darling? I wish you all the best and hope you'll keep us updated. This place is so awesome, I just found it a few days ago and am hooked, lol! Welcome~!
