Polydactyly is a congenital abnormality, genetically inherited as an autosomal dominant trait of the Pd gene with incomplete penetrance.
Normal cats have a total of eighteen toes, with five toes on each front paw and four toes on each hind paw; polydactyl cats may have as many as eight digits on their front and/or hind paws. Tiger, a Canadian polydactyl cat with twenty-seven toes, was recognised by Guinness World Records as having the highest number of toes on a cat. Various combinations of anywhere from four to seven toes per paw are common, and the number of toes on either the front or rear paws is typically the same. Polydactyly is most commonly found on the front paws only, it is rare for a cat to have polydactyl hind paws only, and polydactyly of all four paws is even less common.
Welcome to your family, polydactyl Sorcha!