I have had a great deal of success working with dog aggressive dogs at local dog parks. This may seem strange at first but works very well. We DO NOT enter the park with the aggressive dog. We do all work on the outside of the fence at a safe distance. We work the dogs using HIGH VALUE food reward, or toy, and the correct equipment for management. We teach the dog that if he stays in a calm, clear state of mind, he earns a great reward. They quickly learn, when around other dogs, great things come from their handler.This, in turn, teaches the dog to pay attention to its handler and not the other dogs.