Our three get into from time to time and sometimes they sound so mean, I'm afraid they are going to hurt each other. We always intervene when it's getting too out of hand.
We make a sharp noise, shake a can of coins or spray water to stop the situation.
I agree with the other poster, we don't put any of them in their crate or playpen, because we don't want it viewed as a punishment place. These our their sleeping places and for Camden, she stays in a playpen when we are gone. So we don't want it viewed as negative.
I've said this in another post that the dogs get over these situations alot quicker than we do! They are like siblings and they get on each other's nerves and fight for attention. Then they kiss and make up and start it all over again!