Gosh, Anna, that's a really good question! I'll be interested in seeing the replies too!
My cousin is raising a pit bull from 8 weeks old, she is tough and has many years experience with the breed.
Even with that, this (neutered) dog (now age 1) went after his "play date" dog that he's known since his puppyhood, causing damage to the playdate dog, expensive vet bills, stitches etc and my cousin was lucky she got the pit to release his jaws (she had to kick him and kick him).
She can NEVER trust him again. She said it's a good thing the other dog will be fine and it was her BFFs dog because she'd be looking at the butt end of a lawsuit that would probably take her house.