my friend has a rottweiler and he's one of the sweetest dogs i've met. none of those dog breeds are necessarily dangerous, they're just used most often in dogfighting rings and by people that use dogs to hurt other people because they're bigger, stronger breeds and that's given them a bad image. they all have the same temperament as any other breed of dog unless they're treated to act otherwise. in terms of how often they bite, smaller dogs are actually more dangerous than these bigger dogs. there's no such thing as a bad dog, only bad owners; it all comes down to how you treat them.
They were bread to be fighting/attack dogs, it's in their nature to be somewhat violent. Sure they can be sweet animals like any other, they just have a higher risk of injury to others because they get overprotective or angry. It's like how golden retrievers have a thing with sticks and playing fetch, they were bread to like them. :x
Also, is it bread or breed? ?_?