1. Rule out a physical problem. A chemistry panel, bile acids, and thyroid panel would be appropriate. A variety of health conditions can increase aggression or make the dog uncomfortable and hence more apt to bite.
2. Once a physical problem is ruled out, find a trainer or behaviorist who uses positive methods of behavior modification. Recommendations would include a leadership program like Ruff Love or Nothing in Life is Free, positive training like clicker training, setting a schedule, taking away priveledges, taking an obedience class, working obedience daily, playing the trading game, etc. If the trainer recommends physically correcting the dog, find a different trainer. Treating a aggression with aggression is asking for disaster.
3. While you are getting your referrals and finding a trainer, start a nothing in life is free program and restrict your dog's priveledges. Basically it means your dog has to do something (sit, down, a trick) before it gets any attention, food, pats, going outdoors, etc. If your dog sleeps in bed, have him sleep in a crate or on a dog bed on the floor. If your dog sits on the couch with you, give him a bed on the floor instead.
http://www.sspca.org/Dogs_TANSTAAFL.html
He has figured out that by biting or threatening to bite you, he is in charge of the situation. This behavior has been effective for him. He gets to keep things or get out of doing things. Unfortunately, this is a dangerous behavior that is inappropriate. It is also a very common problem in toy dogs who rule the house, especially manipulative Maltese. These are smart dogs!
Professional help is the best way to go. Any advice given on the internet does not fully take into account your specific dog or how you and your dog interact. A trainer or behaviorist who actually watches you interact can often give better recommendations to help improve your relationship with your dog.
