It has been awhile since I have posted. My 3 year old spayed BC is submissive when meeting other dogs, but does like to play after greeting a dog she knows, if the dog is not too rowdy for her. Last night after rally class she and her younger Aussie friend (about 1 year and same size as Star) were playing off leash with both owners present and supervising. Their play consisted mainly of running around after each other in a big space. While it looked like both were having fun, when Star, when running, started to show her teeth I leashed her up and we quit. They probably ran around for about 5 minutes before this started and Star was getting pretty excited. Her tail was up as when she plays and she was not growling. Was this play or aggression? She can snap at new dogs occasionally at class, so I am very careful on introducing her to new dogs, but do want her to have the opportunity to run and play with other dogs. She and this dog had already met several times on leash and both expressed the desire to play on leash. We do not go to dog parks. My previous BC was a more low key BC compared to Star, though still quite active, and did not show teeth, so this is new to me.