We have established dominance over him by laying him on his back and putting our hands around his throat until he stops growling at us. We also grab him by the snout and hold it closed till he stops growling. We discipline him by rewarding good behavior, and putting him in a time out when he is bad. There are always treats involved with good behavior. He does hurt our girl pup. He means it when he bites her. He is not playing. He scares the piss out of her literally. Sometimes we are there, others we are not in the room, but we always come running to get him off of her. When we get him off her, we sternly say bad boy, and put him in time out. Our beagle loves other dogs. It is only her he is that way with. He also loves people. It was only my son and I we had a problem with.