The dog needs training. He needs to know YOU are the pack leader. Maybe you should write to Cesar Milan, you could end up on TV.

Here is a link to his website...
http://www.cesarmillaninc.com/about/
Seriously though. I've been watching the Dog Whisperer a lot lately, and when it comes to dog psychology, that man is a GENIUS. I swear I think he was a dog in a past life.