Well, I am not feeding them together or letting them have chews together. This is what happened and I am almost at my breaking point and it has only been 48 hours. I told everyone that Dirk has been growling at Isabella and others when he is eating and someone walks into the room. Well, he was laying on the couch and Isabella went to climb up on the couch with him and he growled at her. Just a low grumble and Sugar hears this and jumped from one couch to the other and tore into his ass. I had to yell at her to get off...she did immediately and I sent both to their kennels. I am so scared that something bad is going to happen. They were getting better together. I had no tiffs at all today until now. I really am starting to think that Sugar has turned into a different dog in just 6 months. She has never shown any signs of aggressios towards any dog.