I have a rescue dog, Gandolf, now about 3 1/2 years old, male, german shepherd mix. He is dog aggressive and has shown aggression to humans (he has nipped at several house guests, and bit a neighbor in an electric wheelchair who was passing by in the alley). We have done obediance training with him, had private training with a trainer who works mostly with shepherds, done grumpy growler classes, and consulted with a behaviorist. Everyone has said we have a management issue, and that we need to practice good leadership skills/rules ("nothing in life is free" type rules), which we do diligently. He gets exercise often - I run with him and my husband takes him on a bicycle we have set up for him to run next to. We use a gentle leader and he walks nicely on a leash (no pulling, no lunging at other dogs, etc.). The behaviorist labeled his aggression as dominance aggression, and he definitely would take over if we relaxed the rules. We are very careful with him when we have anyone in the house - he usually wears a muzzle. With other dogs, he is unpredictable, and we only let him meet new dogs if he is wearing a muzzle and is leashed and obeying our commands.
Anyway, I recently saw a book by a man named Cesar Millan who has a dog camp in the LA area, and I believe he claims he can rehabilitate almost any aggressive dog. I don't know too much about him, or his techniques, other than that he advocates a leadership model. I read a brief section of his book that indicated that he solved one dog's aggression issues by training the humans to act as leaders, and then by reintroducing the dog to a pack of dogs he has at his camp, so she could learn acceptable dog behavior from them. Apparently, this dog started a scuffle, but he made the dog lie on its size (by force?, by what method, I don't know), and let the other dogs sniff her. He apparently kept reintroducing her slowly to the pack and by the end of a month or so, she was getting along with all the dogs, and showed no aggression. Is this mainstream thinking on aggression, or kind of crazy? I don't know if he had the dog muzzled, or??? Anybody know how it works, or have an opinion about it?