I have an 8 year old male jack named Skip, and a 4 year old male jack named Jake. When we brought Jake into the mix everything was fine, until he turned 3. Jake started to attack Skip, at first is was just growling and there wasn't any blood shed. As time goes by the fights between them got more frequent and more violent. Yesterday was the worst Jake got a hold of Skip, and he is torn up really bad. Jake ripped a huge part of skin off of Skips face. I also noticed that Jake goes for Skip's neck when they are fighting. Please someone tell me how to fix this! Is this common in jack males?? What can I do?? The pics are Skip after latest fight.