most working dogs have that killing in them ive keep patterdales my old patterdale dog the times ive saved him from being killed by a bull cross.he will start it evrey time he thinks he is the same size but i can see it cumeing before it kicks off.but the thing is with bull cross thay have pit in them so getting them to stop is a job in its self.not running you down mate becuse dont no you or your dogs.but if it was me i would no that if a dog turns on my bull cross he will kill it or try to.