With all my puppies I find that mouthing stops when the dog realizes it can be unpleasant and it is NOT at all rewarding. 1. Do not reward – He thinks they are doggie games and can include tug of war with your arm, or you are a teething toy, or if bothered enough you may dispense a treat to distract him. In all 3 cases he wins. What to do: Don’t yell, thrash and NEVER pull away or use your hands to push the dog off. Move forward, push and throw the dog off balance so he has to let go. Repeat as often as you must. 2. Make it unpleasant – “Mouth back” more and better. I have always grabbed my dog’s mouth or teeth when they put their mouth on me. It’s not to hurt, just to make it uncomfortable so they want to get you out of their mouth. When they spit you out, you may praise. Add the command “drop it” and practice on toys.