Kathleen, "Fear biting" is not necessarily something that always goes along with fearfulness or shyness. I have a pathologically shy Rescue Berner (Shadow) who is very timid around people, and in the house, but is much more comfortable outside and with other dogs. And he's not particularly "mouthy" so biting is not his first response - freezing or fleeing are his coping mechanisms.
Several factors may be contributing to your boy's reluctance to participate in puppy play session. He may feel overwhelmed in a group. Has your trainer tried to have more than one play group going? She might try having him play one-on-one with a dog that is gentler or more his speed in terms of playfulness. Some pups can really benefit from one-on-one play (my Mickey was similar - with people he was a super-sweetie and very outgoing but he hid under the chairs for the first 3 or 4 weeks of puppy K. To this day he prefers one-on-one play to those multi-pup pile-ups that Labs seems to love) When he exhibits this " cowering" does he come up to you for reassurance? And do you give it to him? This comforting may actually be reinforcing his timidity. As hard as it may be for you to resist, it is important not to give him such reinforcement. When I assist at our training classes, I frequently tell the owners to ignore their dogs and then I will toss treats to the "shy" ones when they are out observing the play session and esp. if they try to investigate or greet the other pups. This can be helpful too. Dogs all have "breed personalities" and individual personalities. He may need to find just the right friend to "click" with. Does he get much dog-dog interaction outside of puppy class? And have you considered bringing him to class early so that he can investigate the building alone? Sometimes this can help a dog feel more settled when s/he has a good sense of what's where, etc. You don't describe this other class that your trainer is recommending -- can you tell us any more about it? I know that many other folks on the List have experience with shyness and training issues and the more information you can give about behaviors and specific instances will help us to help you. Good luck and let us know how your little guy is doing Catherine Young Madison WI Shadow, Mickey and Jenny (BMD) Max and Emily (cats.....)