These four or five cats will not let the neighbors’ dog come onto their property. The dog is convinced it’s a game; you can tell that by his body language. And maybe it is–note how careful the cats are never to actually catch him. I’m sure they could, if they really wanted to. Yes, I think it is a game. These critters are a lot more sophisticated than we give them credit for.
P.S.–You can’t get fence lizards to do things like this.