Aggressive Behavior-Golden Retriever

Question
Hello,
I have a 7 month old golden, who ways in at 70 pounds.  He was neutered last week.  At the same time, we began using a choke collar to control him on walks.  We had previously been using a plastic chain like collar with inverted point.

He is always on a lead, even in the house.  He's successfully made it through two behavior classes with pretty good results.

He responds to hand signals and voice cues.  I would estimate that he's a typical loving golden 99% of the time.  However, the single percent he isn't, can be very destruction and scary.

His attacking behavior started at about 5 months when I would take him to an off leash area near my home.  We only enter there if we can be alone.  As I was teaching him about water and getting him to enter streams, he would suddenly race up a hillside or down the stream then come back at me snarling, baring his teeth and jumping up.

My only recourse was to grab the lead and attempt to get him under control.  I found no other recourse to control him, so I used my knee.  I forced it into his chest.  Most times he would stop and sit down.

That was 2 months ago.  Now he works well in the off leash area, but has started attacking me on walks, while wearing the choke collar and being on the lead.

This morning, I had to choke him in order to bring him under control.  I hated to do it, but he wouldn't stop for at least 10 minutes.

Besides the attacks, he is tearing our back yard up eating and carrying off anything he can get his teeth into.  We do not chase him, as the does nothing.  We try to coax him into the garage by offering a treat.  That works, but it takes a while.

Help, my wife and I love the dog, try to treat him in the same manner, but we're at the end of our patience.

Answer
Aggression isn't common in Goldens, but dogs don't read and follow breed descriptions.  It is quite evident he doesn't understand who is the pack leader.  It sounds like both the classes you took were useless ones about the dog sitting, not you being top dog.  There are better ones out there.  Pick up a good book such as The Art of Raising a Puppy, ISBN 0-316-57839-8  See http://www.dogsbestfriend.com/ and also http://www.dogbreedinfo.com./topdogrules.htm