[poohbearsmom]

Obedience training is for YOU to learn how to teach your dog behaviors you want, and to teach you how to extinguish the behaviors you do not want. It would likely do you well to research and read some books on dog behavior and body language.

I concur with the others; it does sound as though your boy may have missed out on some important imprinting. His lashing out when pinned is not good - he's either scared and fighting back, or he's very dominant with the other dogs and when pinned it pisses him off. Either way, YOU are the boss and need to take control of the situation.

Dog parks are not the safest place in the world to take a pup to. Too much likelihood of a very BAD imprint occuring. Please read the link provided in the post above, you might think twice about taking your boy there. If the other dogs are pinning him because he's a rude little tyke, you are running the risk of him being attacked badly when he doesn't back down to these dogs.