Toby is fear aggressive. It is much worse with bigger dogs and when on leash. And it's getting really serious Last Monday in class, we were doing a 5 minute down-stay. One of the dogs in it adolescence stage (who makes some of the least aggressive dogs in our class seem aggressive) was jumping around. He jumped too close to (almost on top of) Toby and Toby attacked. It lasted only a few seconds but it really scared everyone. He was going for the face, but I knew he wouldn't hurt the dog. I have a lot of control when on leash, but can't help it when he is off. First off, I have ordered a dog to dog Aggression DVD to fix his aggression, but the root of the problem has to be fixed first. I believe he is like this because of his sister, Hannah. Hannah is toy protective. She tries to take Toby's toys, and will growl at him if he has any. Toby used to just trade off toys with her, because she was never satisfied. But then they started fighting (going for the face, niether have ever hurt each other). We have kept this to a minimum by not getting out toys unless they are alone. But they will still do this with anything they decide to carry around. Neither of them are aggressive to people, not even if they are taking a toy/chew from them. So it is almost like a sibling thing that has gone further with Toby. This might take a while to fix, but does anyone have suggestions? Do you think it is possible to cure Toby's aggression before I've fixed the problem with Hannah and him?