Aggressive at dog park

Question
I have a5.5 mo. old black lab male, he is very, very docile at our home and listens, we walk even w/out a leash and he obeys and stays close, comes when I call him etc. I also have a10yr old yellow male who has trained him well in that aspect. I have started taking the dogs to a local dog park, so the puppy can get more running, as my old dog doesn't run and play that well anymore. My puppy acts very aggressive w/ other dogs at the park, and absolutely won't listen to me at all, even when I have him on his leash to walk him into the park he is twisting and pulling all over the place, to the  point where I feel as though he will hurt himself, because I don't let go of the leash?? He will be getting neutered here in a couple of weeks, but doyou have any other ideas on what to do???

Answer
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/ For more on being top dog, see http://www.dogbreedinfo.com./topdogrules.htm

Is it true aggresion or does he just want to play rough?  If so, identify other owners of rowdy youg dogs and let them have at eachother.  Here is a link to picture of a friend's dog enjoying a visit with mine, http://www.photolocker.net/images/Labman/gretchenandellaplaying.jpg

Now your puppy is 5 months old, you can go with the metal slip collar with the rings on each end. Otherwise you could damage its windpipe. Put it on like this for the usual dog on the left position. Pull the chain through the one ring forming a "P". Facing the dog, slip it over its head. The free end comes over the neck allowing the other end to release pressure when the leash is slack. A five month old's head will still grow some. If you buy one that easily goes over the head, it still should come off leaving the ears when the dog finishes growing. You need a good 6' leather leash, although you may not want to give a young puppy a chance to chew it.

Easier dogs will give up their pulling with a few good snaps of the leash combined with a stern "Bad dog!". You can work up to forceful corrections with the leash doubled up in both hands and your whole body behind it. But you don't want to use any more force than you need. One gentle technique I like is to just stop when he pulls. He wants to go. If you move forward when the leash is slack, and stop when he pulls, he should quickly figure out the only way to get to go, is not to pull. This is about teaching him not to pull, not getting somewhere. The man that taught it to me said "If in a half hour you haven't made it out to the front walk, fine, you have taught him a lesson. Pulling the dog backwards is a good technique too.

Still, you may want to switch to a head collar. The leading brands are Promise, Haltie, and Gentle Leader. They have a strap going around the dogs nose looking something like a muzzle. They work by pulling the dogs head around. No other way gives you such great control with so little force. The prong collar is now a dangerous relic of value only for its macho looks. Do not consider using one without hands on instruction from somebody with plenty of experience with them.