Unfortunately they didn't need to be trained to fight. They are a terrier breed and it does come naturally to them. Man has manipulated that instinct to suit their own entertainment. The pit bull type dog was used to hunt and hold wild boar and bear and then to bait bears for entertainment. When bear baiting became illegal, they used bulls, when baiting became illegal, the pit bull actually had a respectable job on the farm and in the work place. On the farm, the dog was used to help move large stock, in the butcher's, the dog was used to hold the animal while the butcher did the slaughtering. Of course it didn't take men long to figure out that they could still make money off of these dogs, they'd pick the most animal aggressive ones and pit them against each other. They'd breed the winners and so the story goes. Human aggression was never tolerated in the breed, if a dog was aggressive towards a person, that was a death sentence for the animal. That's why most of the time when you see all the headlines of pit bull attacks, most are cross breeds or something else entirely.
My girls will squabble from time to time and I'll break them up. I'm not afraid to stick my hands in there to do so. Now if it's some of the other dogs, there is no way in hell my hands are going near their mouths. I've only been bite one time by a pit bull and it was my fault. I sat on him by accident and hurt him and I got nipped. I've been bite bad by other breeds because they will redirect onto humans.
