[horsnaround]

This sounds like it could really get bad fast. The biting and breaking skin is not good as you well know. Maybe when he is getting that way instead of focusing on that behavior. Get a treat and change his thinking right away. Get his mind busy teach a trick. It sounds like he is playing hard because the kids are playing hard. But if you can get his mind to switch to something else right away it may help. Just a idea of positive instead of negative. The biggest thing is being consitent in your method. Good luck.