[Mary Beth]

I would be concerned about the size difference between the BT and the gsd especially now that the play is getting rough at times. The incident with the dogs in the yard does sound like redirection - your gsd got excited - frustrated and then redirected on your little BT. My suggestion is that you keep the dogs separated when you are not at home and also when you are at home to monitor their playtime so it doesn't get out of hand.