I play tug with my pit/boxer all the time.....he's a master at it! Jaws of Life I say! LOL
Usually the rules for tug are:
1. Human always wins! I let Smiley win about every 5 tugs, but he is well versed in the game and always "Bring back" the tug for another round. We had to build up to this.
2. Never Let them Growl! Haha! It's part of the boxer's playstyle to growl! But, if Smiley begins to growl, I know it's because he is getting overexcited, so play ends immediately. Pits really shouldn't play tug, but I only play tug with the boxer side of him! LOL
3. End the game with another toy! If playing tug, then the last game should end with a trade of a toy so the dog knows the game ended and he can continue his own playing with his toy to release any energy built up from tugging. And no retailliating against your hands for another round.
Just remember - never yank or jerk the toy where the dog's head and neck will be jerked as well. You can really do damage to the neck muscles if not careful, especially with young pups. And no jerking back and forth, that's really dangerous to their muscles and tendons.
Make sure you use the "no Teeth" rule and your dog has complete bite inhibition. To be bit in an excited game of tug can really hurt you and make the dog apprehensive with your hands as not to cause you pain again. If your hand ends up in his mouth during a tug session, immediately stop the game (I use "no play" command) and let them calm a bit before initiating again.
I always then finish the session with the "Kiss me" command and trade a toy.......hey, I love my kisses so it's an excuse! LOL