I have Pittbull/Australian Cattle Dog Mix and hes gonna be 3 on January 22nd. My brother recently got a Pittbull pup and my dog wont have anything to do with her. Whether it be in the house or out in the yard. His hair goes up and he attacks her. What do I do about it? I dont want to get rid of him. I mean what if the aggression is only starting with the other dogs, and next moves to people. I dont want to have to worry about my girlfriends special needs kids because hes getting itchy and aggressive.