I don't know if ALL dogs can be trained to fight, .....but it is not only this breed that has had a bad name - - -Collies ( Lassie type).There was a time when they were known as " one which could easily turn". What about the G.S.D.??? ( by the way I have owned both) - they were the most fierce of all. My goodness, in the early '70's an entire male or non-sterilised female was not allowed into Western Australia, because of the fear of them inter breeding with other dogs. Mention their name and you would shudder. - - - - now people sell from their back yard, and " Oh yes, it has Shepherd in it, it will be a good dog." (maybe in it's left toenail).........
Then the Bull Terrier ( Pig Dog ) - nasty creature, got to watch those buggers......and the Staffie with it's ""Locking Jaws" - nasty piece of work them.

What about the small dogs, the little terriers, that attack and bite and forget to let go, nothing is ever said about them ( I have had terriers too ),,,,,,,,,and the small Poodle ( I have had many ) they can be nasty too, and bite. - - what is said about them??? Nothing except how smal and good they all are to have in a back yard.

I have never had a Pit Bull Terrier, and they have a bad name here, BUT - like any big dog, it needs training, obedience most of all, . . . . . . . but because it has a "Tough Guy" image, bad people get them and do bad things with them. Some dogs will turn, it does not matter the breed..like humans, some are good, others are not!!!