we use chew bones, but what really keeps China busy, believe it or not, is an empty water bottle. Now I dont know if this is healthy for her but she just plays with it until she completly destorys the small bottle. The other thing, that we us is a kitten. The kitten is a little younger then China (she is now 4 mos), but I'll tell you, they go at for hours. I've never seen a dog play with a kitten like China. When she starts to get rough we calm her down by either giving her a time out in her crate, and the kitten too, because she's just spitting fire. We never leave either of them unattended. Because at about the 3rd week the kitten got a little confuse and wanted to nurse and China was letting her. Well that is a no-no, so we got a spray bottle and just keep our ears open when it was quite it was time to see what was happening. We've made it though that. Any way hope this will give you some ideas. With a boxer anything is possible.