Summer and Kali play often. And occasionally it gets out of hand and Summer puts a stop to it. If so, it usually ends with Summer growling. Thats usually enough to let Kali know its over. If Kali doesn't take the hint, Summer will get nasty and bloodshed has resulted (nothing serious). So we keep an eye on them when we are with them. I constantly tell them to play nice, because they know not to get me mad, because I WILL get involved.