Hendrix is now 15 weeks old and he loves to play with everyone and every dog in sight. My parents have a lab who is 9 years old, with hip problems who has never been around a young puppy (let alone an energetic boxer!!!) Hendrix loves to play with Seamus (the lab) but because of Seamus' health problems, he can't play back in a very physical way. He does bark and growl back at Hendrix, but his tail is wagging the whole time. We don't want Seamus to get hurt, or to snap and hurt Hendrix, but we also don't want to let Hendrix think that he's "won". I thought that as long as Seamus' tail was wagging it was all fun and games, but we don't want anyone to get hurt or learn the wrong type of behaviour. Is allowing Hendrix to "play" this way going to teach him to be too aggressive? Any suggestions as to how we can calm the situation down?