I would be cautious, particularly if you have a dog. I adopted a pit bull mix from a shelter when he was about 3 or 4 months old. He had been neutered, of course. He and my other male dog, a gentle border collie, got along great until Bone was about 6 months old and then Bone started attacking my border collie. We took him to months of behavior therapy at U of Penn vet school, put him on puppy Prozac, etc. but nothing worked and he was insane around other dogs. The two dogs had to be kept separated at all times. Bone was extremely lovable with people - particularly children - had a great sense of humor (really!), loved to sing (I promise this is true!), and lived a long and happy life, but even as a senior citizen he was vicious around other dogs. He did come to me with some scars on his face so perhaps he had been pre-trained as a fighting dog as a little puppy, I don't know. I do think, though, that no matter how conscientious the owner some dogs might be hard-wired to fight.