I have had all 4 of these dogs since July, everything has been fine. They have a communal living area, with individual beds and food dishes. In the last week, Charlie has started violently attacking Ace for no reason. Ace is a larger and un altered male dog, but he absolutely does not fight back, he cowers and screams when Charlie gets aggressive with him. I have tried seperating them, but that isn't practical for the long term, and Charlie is pretty much attacking Ace on sight now. Charlie is also showing signs of aggression towards myself and my teenage daughter (who I would say is his primary care giver).
What is happening? I have made a vet appointment for Charlie next week, but I just have no idea what could be causeing this sudden change in behavior. Anybody have any thoughts?