Doberman behavior problem

Question
I know you are not a vet but I thought I could get an oppinion from you about my dog.  I have a 9 year old male Doberman (pure breed) He has always had a strange nature (very aggressive) but tolerable.  Recently he has become more aggressive (snapping, growling at all family members) he even bit a girl at my son's party because someone left the gate open accidentally.  I let that go because he was doing his job protecting his home and owners and reacted to seeing a yard full of strangers.  I love the dog very much and don't know what to do about this. He has never turned on me but recently he has been growling at me for no apparent reason. I have never felt threatened by him until now.  I am also worried about my 14 year old son  being around him.  I was thinking about bringing him to a vet to see if something is bothering him or hurting him.  What is your opinion?  
Thank you.

Answer
Hi Carolyn!  I can completely understand your concern.  You mentioned that he has always been aggressive...and it is normal for a tolerable behavioral problem to become more of a problem as the dog ages.  I would definitely think that this is what is occuring now, and this is normal for a behavioral problem to become worse with age.
I would definately suggest a vet visit to see if there are any ailments present that could be causing this mulitplied aggression.  If this is a behavioral problem, I don't know how you feel about medications, but there is a medication called Acepromazine which helps in situations like these.
The medications causes the dog to be a little more relaxed...not "loopy", just relaxed, which causes a decrease in aggression.  It's definitely something your veterinarian could talk to you about.
Please keep me posted and best of luck!
Hilary