My dog is from DDR bloodlines and has a VERY strong herding drive. He will play ball till he can't move,will try to herd everything. The problem I'm having is that ,well let me give you an example. The other day we were over are friends house and he was playing with 5 other dogs. He's great with that. Well one of the dogs owners grabbed a ball and ran with it so all the dogs took chase,well my dog, Cole,was right on his trail and when he stopped he nipped his ankle. It wasn't a bad bite but a small nip. I say no as soon as I see this and he put his head down but he has done this a few times now. How do I correct this? If I correct after it happens its to late.