Hmm, I need to watch more closely. I've never seen mine just walk backward for any reason - unless forward was impossible.
I did some back up practice with my mare tonight - forward and backward on railroad ties. And backing up a hill and down a hill. She was very trusting and didn't swing around. Tomorrow we are loading up with a friend and driving a few hours to stay at a riding resort (for a week) Richard Shrake is the clinician of the week - Thought I'd get her "backwards" in motion so she doesn't fly out of the trailer.