I've got an American bulldog (not to be confused with and American pitbull) he's the most docile sod you'll ever meet, you can Chuck a toddler on his back and he won't even bat an eyelid. He's been brought up as part of the family, great with other dogs....If someone broke into my house, he would probably stroll up to the burglar and wait for a smooth, although the size of him woul be enough to scare most off. Like a previous poster said. It's how you treat them and look after them that makes the difference. Any dog, no matter what breed will attack if it's been mistreated