Do you ever watch the Dog Whisperer?
He is a dog behavior specialist on National Geographic channel. It's so interesting I record it. Last night I watched 2 episodes and though the problems were different the solution was the same. Teaching the dog that they are
not the pack leaders.
Not an expert on how you go about that but it's more of a behavior issue than something you could get through training class. This guy is real big on putting the dogs on leashes and not allowing agressive or dominent behavior of any kind.
http://channel.nationalgeographic.co.../dogwhisperer/