I have a very similar problem to Kim Schiller ("Two brothers who hate each other), except occurring with two sisters, and in my case, I know why they are behaving this way. I lived with my allergic parents for a month (they had to stay in the tool shed), then they had to stay in a kennel for two weeks (totally against my wishes). I've had them checked out by the vet since, and they're healthy, but now that I'm in my new house and they're with me, their behavior is getting worse. What to do?!?!