Polydactyl cats may have as many as seven digits

Normal cats have four toes and one dewclaw (thumb) on each front paw and four toes on each hind paw. Polydactyl cats may have as many as seven digits on front and/or hind paws, and various combinations of anywhere from four to seven are common, although each of the front and rear paws are typically the same. Polydactyl is most commonly found on the front paws only, with polydactyly of all four paws being less common. It is rare for a cat to have polydactyl hind paws only.

The true polydactyly - commonly called mitten foot, mitten cat or thumb cat condition - is a congenital abnormality, genetically inherited as an autosomal dominant trait of the Pd gene with incomplete penetrance. This type of polydactyly is not life-threatening and usually not even debilitating to a cat. Some polydactyl kittens initially have more difficulty in learning to walk than normal animals. However in some cases polydactyly appears to improve the dexterity of the animal. For example, a common variation with six toes on the front paws, with two opposing digits on each (comparable in use to human thumbs), enables the cat to learn and perform feats of manual dexterity generally not observed in non-polydactyl cats, such as opening latches or catching objects with a single paw.

Feline radial hypoplasia (see squitten) is a mimic of polydactyly and is considered a severe condition. Radial hypoplasia may cause the formation of extra jointed toes, but it is not a result of the Pd gene normally associated with polydactyls. It thus does not cause the "mitten cat" or "thumb cat" condition where the extra toes occur separated from the normal ones just like a dewclaw, usually associated with an additional pad which makes them look like an underdeveloped foot sticking out near the base of the normal toes.

Rather, radial hypoplasia-related extra toes are immediately adjacent to the normal ones, giving the cat overly large, flat feet - colloquially known as "patty feet" or &