Why Does My Cat Have Six Toes?

My cat has 6 toes on both of his front paws. What is the explanation for this?

There are two possible causes of extra digits in cats: Polydactyly (supernumerary digits) and Radial Hypoplasia (under-developed radius bones). Normal cats have four toes and one "thumb" on each front paw and four tows on each hind paw. You did not state if you meant that your cat has 6 digits in total on each paw, or if he has 6 toes and also a thumb.

Polydactyly is an inherited congenital abnormality. Polydactyly can give rise to various combinations between four and seven digits on the front or hind paws, and each of the front and rear paws are normally the same – in this case it seems that only your cat’s front paws are affected. It is very rare for only the hind paws to be affected. A polydactyl cat can only result if one of its parents is polydactyl. It is believed that the first breed to exhibit this trait was the Maine Coon, but it is considered a fault in all breeds except the Pixie Bob. This type of abnormality is not usually even debilitating to a cat, but some affected cats have difficult learning to climb.

On the other hand, Radial Hypoplasia can be a very serious condition in which duplication of digits is only one symptom. In Radial Hypoplasia, the radius (one of the two long bones of the lower foreleg) is unusually short, giving the impression that the paw is attached to the elbow. Cats affected by Radial Hypoplasia have much shorter front legs and therefore tend to sit like a kangaroo and hop like a rabbit, since using all four legs to walk can cause a great deal of spinal strain. Even though in some cases affected cats have only minor symptoms, they should not be allowed to breed since offspring could have much more severe abnormalities.