Thank you wikipedia for this: http://en.wikipedia.org/wiki/Cheetah

It had everything I needed to get an idea of what Walt should look like, what noises he can make, that his claws are only semi-retractable, and I've made him a king cheetah after looking at the picture and description of that mutation. Didn't really give me any ideas of possible eye colors, but that's it as far as what I couldn't get from it.