I have to agree that I could never live with dogs who sought to fight each other to the point of harming or killing each other. If all my dogs couldn't live in harmony then I would have to do some shuffling around to see who would be getting rehomed. That said dogs that are used to starting fights with other dogs might not be too adoptable, no one wants to take in a dangerous dog so I would have to make sure it goes to a one dog family only. Living in a home where you have to be on guard 24/7 would be too much for me.