agression

Question
We, my husband and I, have a 3 year old shih tzu who has become very aggressive with his treats.  He doesn't have problems with his food dish, as I can easily take it away from him without any incident.  However, when it comes to his treat he is very protective and growls if we tell him to leave it. The strange thing is that sometimes he moves his treat close to us, up to our hand, as if to encourage us to hold it while he chews.  He is neutered and is an indoor dog, but I walked him daily and he has been very well trained, and through several obedient classes to graduation. Another thing that recently happened is that he bite my 30 year old son who was going to take him for a walk, but he didn't want to go.
Please advise

Answer
What type of treat?  Maybe you should take the treat away completely.  A treat is meant as a reward for good behavior and if he is not doing what you want him to do and is misbehaving than withold the treat.  I don't like to give rawhide or long lasting chewing treats, I usually give an instant reward - dog cookie, carrot stick, apple slice.  I hope that after the biting incident you corrected him, kenneled him (time out), and then had your son take him for the walk after all, never ever let the dog have the last word (remember you are the boss).  I'm not sure what is going on in the home, but sounds like he may be going through some changes and is going through depression or insecurity issues.  You may want to talk with the obediance trainer about a few private refresher lessons.  Sorry I couldn't be of much more help.  Not knowing all the facts it's hard sometimes