Okay, now I have never thought I would be posting this, but when my KeeKee goes outside to her x-pen to potty she stands upright against the side and goes standing up. I have never known a dog to do this before. My Mickey not only curves his back with the back legs up against the front legs - he holds up his back legs up off the ground - it's like a balancing act and he is very good at it.
T.