My Megan used to growl when we played tug-o-war, or she played with her favorite toy, a toilet paper tube with the ends pushed in. Megan never bit or was mean, she just acted like the little ratter that she was. Gina, my new puppy, is a growler/talker, and she growls while playing, she hasn't graduated to tug-o-war yet. Gina has a few toys, but her favorite is the toilet paper tube as well, she pounces, and attacks it, throws it and carries it around, all the while growling. She is a funny little girl, and as long as she's nice with the playing, she can growl as much as she wants. I can't wait to play tug-o-war with her.
Cheers Quad