Polydactyl cat

A black cat sitting on a garden chair. Its left front paw faces up, displaying its seven toes.
One of the polydactyl cats at the Ernest Hemingway House in Key West, Florida. This particular cat has seven (two extra) toes on each paw.

A polydactyl cat is a cat with a congenital physical anomaly called polydactyly (also known as polydactylism or hyperdactyly), which causes the cat to be born with more than the usual number of toes on one or more of its paws. Cats with this genetically inherited trait are most commonly found along the East Coast of North America (in the United States and Canada) and in South West England and Wales.