malformalady:

Polydactyly is an inherited trait that is not uncommon and may have arisen from a genetic mutation. Polydactyly commonly affects the forepaws, rarely affecting the back paws. Rear paw polydactyly does not occur without forepaw polydactyly. The number of toes can vary on each foot or can be the same. Most often, a polydactyl cat have one or two extra toes on each front paw, usually arising from the thumb area.

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