I have 2 Male Jack's. The oldest is 13 and the other is 6. They used to be best of friends and it was clear that the eldest was the leader. He was a nice leader, not mean. When his health started acting up (arthritis) and my fiance moved in, the youngest started attacking the older Jack. He will also bite my fiance if he is close to me. He is allowed to sleep in our bed but we have to stop because he growls and snaps at my fiance. We also got a small female dog around the same time(Yorkie/Westie mix). They get along great. The younger one has beat him up several times and it is getting worse. He is drawing blood (ear cuts). The fights can start over anything. The oldest dog could just be walking past and he will attack. The oldest seems to know that he is no longer the alpha dog and is scared of him. The younger Jack glares and is a bully. I do not know what to do!!!?? I love them both and do not want to see the younger one bully or even kill the older Jack. The younger Jack is normally sweet and a mama's boy. I do not want to get rid of him. I want my oldest Jack to live out the rest of his years happy. What can I do to make them happy and keep our nerves calm? If anyone has any ideas that would be great. Some say shock collars, news paper ect...I've tried flipping the youngest on his back and showing him dominance but doesn't stop him from future attacks. Thanks!