Most cats have five toes on the front paws and four toes on the rear, but a small percentage have extra toes that resemble thumbs. Although the condition is formally called polydactylism, the cats are commonly called thumb cats or mitten cats. The trait can occur in any breed of cat.
Extra toes occur more often on the front paws than the back paws. A cat must have extra toes on its rear paws to have extra toes on its front paws. Extra toes appear in a variety of places on a cat’s foot. Some cats have extra dew claws, the short claws on the side of the foot. Others have extra digits that look like thumbs or additional toes, which make the paw wider. You also might see small, undeveloped toes between fully developed toes. The Vetinfo website notes that extra toes can contain extra joints, which allow the cats to use the toes like fingers.
Breeding and Genetics
Polydactylism was once common in Maine Coon cats. In fact, as many as 40 percent of those cats were polydactyl at one time. Over the years, the trait was bred out of the cats to help them conform to cat show standards for appearance. Polydactyl cats inherit the trait from a parent who has extra toes. Forty to 50 percent of the kittens in a litter will be polydactyl if one of their parents has extra toes.
Polydactyl cats are sometimes referred to as “Hemingway cats” in honor of the late author Ernest Hemingway. The Ernest Hemingway Home and Museum reports that Hemingway was given a six-toed cat by a ship’s captain. As that cat bred with local cats, more polydactyl cats were born, and they eventually became a common site in the Key West, Florida area. Today, 40 to 50 polydactyl cats, most likely descendants of the original cat, are cared for by the museum staff.
Most cats have no problems with their extra toes, but in some cases extra digits can make life more challenging for cats. When nails don’t form correctly in an extra toe, the cat might be more likely to have a problem with ingrown claws, which can be painful. Claws that grow at an unusual angle can make walking difficult. Claws also can injure the cat if they grow toward the pads of the paws. Removal of the nails is the solution if they cause pain or difficulty walking. In some cases, a cat might have a twisted limb in addition to extra toes, which can affect the cat’s mobility.