There's got to be a lot of things that aren't good for dogs to chew on. We have a nylon (I think it's nylon) rope that use to have a ball attached on the one end of it. Occassionaly Lola will want to play tug of war with the rope, and we'll play a little and then she'll lose her grip and the rope will slide through her teeth and I'm just like - OW that can't be good. Therefore we don't play like that very often at all. She likes to chew on wood too (sticks), which I would think isn't too bad. Luckily she isn't much of a chewer.