My spouse says that if you use tugging type toys with a dog, that it will make them behave in a more aggressive way. I am of the thought that it would help a puppy to burn off some energy, so long as you keep the game low key. I thought that aggressiveness is an inborn trait that perhaps can be changed to a small degree, but not totally. I await your opinions (pant, pant) and then I can put this disagreement to final rest!!! Thank you pup people!