When dogs are romping happily together, their bodies are like limp noodles. Tails may wag in loose arcs, and mouths may hang open. When a dog becomes tense, his body stiffens. As far as the play itself, one thing to be wary of is speed and intensity. It is a lot easier for play to boil over into aggression when things are becoming fast and furious. Are the dogs racing around the park? The more dogs that are involved, the more potential danger. Also, the more vertical the play gets, especially where dogs are standing on their hind legs and mouth wrestling, the more potential for danger. Watch for actions dogs may take offense to, such as humping, hip bumping or slamming, and placing a head over another dog’s neck or shoulder area. If you notice a freeze or tense body language, stay alert and ready to intervene if necessary. If you notice that your dog is becoming overexcited or playing too roughly, or that other owners are becoming concerned, create an enforced break in the action by calling your dog to you.