overprotective german sheperd

Question
I have a 7 mon old male german sheperd, he becomes "very" agressive towards anyone outside of family, even people he has met before but not real familiar with. He stalks them, barks and and chases when they turn and walk away.  He does not stop when I command him to and does not come to me when commanded. We have a home business in the country and have several employees so he is exposed to lots of people. I am affraid he will bite an employee or visitor if I can't get this controlled. But I do not want to totally ruin the watch dog in him, I have thought of getting a shock collar but sure. What I want is for him to learn to stop the aggresion and to come when I command.  

Answer
Hi Kasha,  Your dog sounds like he is not suffering from overaggression, but instead is reacting on his herding drive.  GSD's are herding dogs, and some have very strong herding instincts which come out as they start to mature.  The symptoms of a strong herding instinct include "stalking" animals or people, barking at them, and then when they run away going at their heels basically "herding" them.  Also, you need to start him in obedience training if you would like to teach him to come to you.  Don't use a shock collar on him.  That is a dominant way to train a dog, and can be a very inhumane way to train him.  The obedience training can also help with the herding problem too.  Hope this helps,

Dawn