Cooper does this too, but only at his house. He never ever does it to Carley, but our neighbors dogs come over all the time (they let them run loose
) and Cooper will run up and snap at them if he thinks they are getting too close to me and my husband or if we try to give all of the dogs a treat. I think it is just his way of saying "MINE". I have bought a squirt bottle just for this and when he runs and snaps he gets a squirt. It does stop him for awhile, but then a few days later he will do it again. He only does this to these dogs when they get close to us to be petted, or when we try to give them a treat, otherwise he is fine with them. These are large dogs too and he just doesn't care, he lets them know he is boss. The squirt bottle does help though. Good luck!