In my opinion, its not mostly bull breeds.. But it seems to me that the bull breed attacks only make the paper/news. I have two large lurchers both male and never once have they attacked each other or even took one bite against each other, they sleep, eat, work and play with together, and never ever has either one of them took badness against anyone, one of them only barks if a stranger walks into the garden, we also had two poms both bitches and they done nothing but bite each other and other dogs and people. My point is most people see through a wee ball of fluff or cute looking dog nipping