Eve, my English Shepherd, would stop every dog running if she could, I'm sure! When we are out and she meets dog to play with, she'll initiate a run out together, then grab at the dogs legs to stop them! Many dogs have done somersaults or really snapped at her but she just thinks this is a great game! (until I tell her off lol). Even with her own pups, she will play with them but when they run, will stop them, then just stands over them waiting for them to run again! Is she just herding?