I have three dogs. The oldest is three years old, he came from a neglected home, but was never beaten. He had a bad skin problem and it was never addressed properly, so it escalated until he lost his fur. That was when he came to me. His owner had taken another dog from her neighbor that was not feeding the pup or giving it water, or letting him in the house, an he was only six weeks old, this is vinny. So I wound up with both of the boys. After three months of medical treatment, Rio is the picture of heath, Vinny, the younger one was gaining weight like nothing I had ever seen. He got pudgy, then grew into all of it. Now almost a year later, after having both dogs plus one of my own, Rio snapped. He has never shown signs of aggression that went beyond making gruff noises that were not quite a growl. We were all laying down, nothing going on and he bit vinny. Then he ran to his cage. He was shaking for about six hours after that. This happened about week ago. I am just wondering if there is anything I can do. The worst punnishment that they recieve is a strong NO, and then they go to their cage for a few minutes. I don't understand what happened. He has not been aggressive since, but I just don't know if I can trust him. He has never tried to be dominant with people let alone aggressive, and I am always in the room with them or in the backyard when they are out. So I do supervise, I am just at a loss. He is not going anywhere, I have decided that, and I have bought a muzzel, so if he is getting excited I can put it on him and we can all play until the energy is gone, but I know there has to be a better solution that will not lead to one of my other boys getting hurt. Any suggestions?