This is a wonderful site to go to for all behavior questions that you may have. A definite bookmark site! Here is the intro for the articles
Unwanted barking, jumping up on people, pulling on the leash, mouthing and nipping, not coming when called… how many dog owners haven't had to deal with at least a few of these common canine behavior problems? It's never too late to train a dog, or to work on his or her behavior problems. Bad habits can be broken, good habits can be taught, and most importantly, with a little effort and love, you can make sure your dog stays a happy member of your family forever!
Should the training articles available here or elsewhere not be effective, contact your veterinarian. Veterinarians not specializing in behavior can eliminate medical causes of behavior problems. If no medical cause is found, your veterinarian can refer you to a colleague who specializes in behavior or a local behaviorist.