I'm having the same issue. I will say though, males with males is a hard thing to deal with. Everyone has that testosterone of who's better than who and to show them all that they are the best. I have a female dane and a male lab mix. She is mainly having the issue that my lab is insane and she has to put him in his place periodically. It's not acceptable to me at all though. She is too big to be grabbing him and shaking him around, plus I have younger kids and she could hurt them when she's not paying attention to what she is doing. It's getting better, but we monitor it and watch. She's still on trial here per se...I can't have aggressive dogs so we shall see if she calms down. I keep a pinch collar and long leash on her while the two are together in the house and they are not left alone in the house together at all right now. At night we separate them: he sleeps in our bedroom on his bed and she has a large kennel that she goes into (we don't shut it unless we leave). She is constantly praised for when our lab can come near her/me and she acts nice. Mainly her problem is that she is pretty protective of me and when he comes near, she would act as if he was a threat. It's a pain, but she's coming around. I'm not sure what all you could do for your situation...I guess I wanted to relate that I know how you feel. I also feed them separately; Duke eats outside and Perdi inside. That keeps down a lot of issues. Just know that it's going to take a while for your boys to understand each other. I have noticed that being outside together running around and playing (even though they are playing separately with me while both are there) has helped my two. It burns off energy, but also mine realize that they are not there to fight, but to have fun. I hope it works out. I know it's hard to always be on your guard with them...hopeful ly they'll work it all out and be best buds!