Four-legged animals have six different ways of walking, our at least most of them do, that are illustrated in this animation. I was surprised to see how a dog uses his left and right legs together in both front and back in the slower gaits. I had assumed that they usually worked the opposite way, as in the trot.
There are exceptions, like my three-legged dog who just does the best she can, and my neighbor's dog who doesn't walk at all as far as I can tell -he just sits on the porch. -via Boing Boing