Both bulldogs have been with me since about 3 months of age. They are both "fixed" and have been since between 4-6 months of age. My male attacked my female the first night she was here over food and i have fed them seperatley ever since. The fighting started about 3 months ago, seemed to be about the time that my female realized she had gotten bigger than my male due to the breed. It is almost like the second he growls or shows any signs of aggresion she attacks to show him whoes boss now. I can't really tell for sure who is starting it since it happens so quickly. we either have to pull them apart and keep them seperated or throw a large amount of water on them. Neither of them have had any obedience training. None of my other dogs are ever involved in any of the fighting, it is specificly between these two, who get along great the majority of the time..