saying goodbye is not pleasent

Question
I have a yorkie maltese and he is three years old and a very good loving dog.  We have a problem which started about a year ago.  Whenever a person leaves the house even if its us the family he gets very mean and barks very aggressive and possibly could bite. We dont know how to stop this nor why he is doing it. We would really appreciate your expert advice and help.  Thank you very much.

Answer
It could be leadership.  Neuter him if not already.  The key to most behavior problems is approaching things using the dog's natural instincts. Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog. Life is much easier if the 2 legged pack members outrank the 4 legged ones. You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at http://www.dogsbestfriend.com/ For more on being top dog, see http://www.dogbreedinfo.com./topdogrules.htm  Don't make the serious but common error of failing to take a small dog seriously.