I was reading about polydactyl cats in Wikipedia. They say that most polydactyl cats have polydactyly in either just their front paws or in all four paws. It's rare that a cat will have polydactyly in their back paws only. My first kitten that I got when I was 10 had 6 claws on her front paws and 4 on her back paws. She died when I was 18. She was a good cat. Her claws that were between her "thumbs" and the rest of the paw didn't move. I now have a kitty that's a year old and has polydactyly on all four paws. 6 claws on the front and 5 in the back. all of her claws are used and they all retract into the paw and out. She's a great climber, a pest sometimes, and I still love her to pieces.