I have counted 5 or 6 of mine and my partners cats that the back leg is changing texture. It seems like the back leg is going grey with a cat head in it.
Hi Brilynn! I've had this happen to my cats before, if you put them into low prim mode then back out it should fix the issue. If for some reason that doesn't do it then send them to the cattery and back.
I have cats go grey on me in full or in part when I'm trying to push my graphics higher than my computer wants to go. Just a possibility.