With small animals, facial expressions do not display well but instead, tails and ears usually show all the emotions. I figure this is a result of how far away the animals are away from each other when conveying those emotions to each other. While watching the film "The Wild" (Disney film with zoo animals vs wildebeests) I was amazed at how close the CG character designs were to the real animals but also noticed the biggest differences between CG and real were tools needed for facial expressions. The joke that Benny (the squirrel) admiring Bridget's spots (the Giraffe) and she saying "my eyes are up here" tells a lot in that as humans, we see each other's faces more then other body parts (except maybe boobs). For animal actors and animated animal characters, the key to making the human audience feel for the soul of the characters is the expressions that are visible in the eyes and face. I have seen rodent faces up close showing that they have a lot of control of facial muscles but just rarely use that control to make facial expressions. Maybe that facial muscle control and facial expressions us humans are used to can be taught to animals to advance animal acting to the level that we saw in Bolt in the "Bolt" movie where facial expressions were seen on real animals by the audience. My idea of developing a computer program that displays an animated character to interact with human computer users was originally to imteract with real animals using animal body language cues to speed up the lamguage learning process for the animals. Of course it can also be used to teach human facial expressions to animals too.