Temperment change

Question
Perhaps you can help us with seems to be an increasingly
stressful issue.
We have a Golden that is now over 3 years old. The dog has
always been great but now over the past 4 months has exhibited
temperament change.

Originally you could always play with the dog, he was a delight..
He has been growling increasingly, now to the point, when you
brush him or when he jumps up for a greeting he could growl.
Its weird because his tail is wagging, but he is growling.
We had taken him to the vet for an ear infection, but that was
awhile ago, we had medicine,which he used to love and helped
but now he seems not wanting to be touched.
He is not inany pain, he runs, plays, eats the same, but seems to
be distancing himself by being aggressive with the growling.
If you yell at him, it seems to worsen, I am very fearful, he is
turning and this problem is worsening.

I do not think, having him neutered would change this, We
purchased him from a kennel, with papers, I am wondering if
there is a problem with some breeds.
He is about 20 lb. larger than normal, which made if difficult to
breed him and now that is long past any type of consideration.

Do you have any suggestions, as this problem seems headed in
a very bad direction.
I have never in my life had any of my pets growl at me, or my
family. If I can cannot trust this dog, I must take some action.
I hope you may have some insight into this issue.
I thank you for your time in reading this and any help you can
give.

Al Lewis  

Answer
It is unusual for a Golden to be aggressive.  Of course, any breed can have a bad line and poor socialization.  I would suggest another vet visit.  It is possible the ear infection has left him deaf and confused.  You also need to discuss the weight gain.  If he is 20 pounds heavier than at a year old, he needs to lose weight.  You also need to discuss neutering him.  It is no cure all, but will make a big difference if the aggression is due to poor breeding or socialization.  His personality is mature now and will be hard to change.
 
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/

How much exercise does he get?  A long, structured walk every day will be important too.  He walks at your side, loose leash, and attentive to you.  You choose the time, the route, the pace, etc.  He does not get to stop and sniff or greet other dogs.  

Here is a link to judge his body condition, http://www.puppychow.com/products/popup_body_condition.aspx