scrappy2

can anyone give me training hints with my 2 year old? I have had him since 7 weeks old and he is fantastic with people, my little terrier bitch and other bitches. He was recently in a fight with another dog which attacked him and since then has been agressive with other male dogs. He picked up a yorkshire terrier in the middle of its back and tried to shake it to death a week ago. I am getting scared to take him out in case he kills someone's dog, any suggestions? Scrappy 2