Excerpt
Believe it or not, but animals
do not walk on the soles of their feet! They only walk on their toes. Let's go in for a close-up of this concept.
When relaxed, a dog's paws are always floppy. That's one of the main distinctions i've noticed between animals and humans: Humans use their hands in a very precise manner, whereas animals use their "hands" in a loose and imprecise way.
The idea of relaxed front and rear paws is especially important when dogs-- or any other animals with similar "hands" and "feet"-- walk. Take a look at the Great Dane to the right. This relaxed-paw quality is something that animators use and know well. It's a principle known as drag, and you can see it if you watch any wildlife special on TV. When animals walk, the paws drag behind in a floppy, relaxed manner. This is very different from the way humans walk. Yes, the joints in human hands are often loose during walking, but they never "drag" behind to quite the extent that you see on animals.