Polydactyl Cats: The Genetics and History Behind Cats With Extra Toes

A standard cat has eighteen toes: five on each front paw, four on each back paw. Polydactyl cats break that pattern, sometimes dramatically. The current record-holder has 28 toes — seven on every paw — and plenty of ordinary pet cats walk around with six or seven toes on their front feet without their owners thinking twice about it. The trait is common enough that most cat owners will encounter a "poly" at some point, yet surprisingly few know where the extra toes come from or whether they mean anything for the cat's health.

A Dominant Gene, Not a Birth Defect

Polydactyly in cats is caused by a mutation in a gene involved in limb development, inherited as an autosomal dominant trait. That means a kitten only needs to inherit the gene from one parent to be born polydactyl — if one parent carries it, roughly half the litter will typically show extra toes. It's also why polydactyl cats tend to run in family lines and in geographic clusters: a few founding polydactyl cats on a ship, a farm, or in a coastal town can seed a local population where the trait becomes unusually common, which is exactly what happened along parts of the New England and Atlantic Canada coastline, and in Southwest England.

Vets classify the extra toes by where they appear. Preaxial polydactyly adds toes on the inner (thumb) side of the paw, postaxial adds them on the outer side, and mesoaxial (the rarest form) duplicates toes in the middle of the paw. The front paws are affected far more often than the back paws, and a "mitten foot" or "thumb cat" look — where the extra toe sits apart like an opposable thumb — is one of the more common and recognizable presentations.

A veterinarian explains where polydactyl toes typically appear and what, if anything, owners need to do about them.

Hemingway's Cats: How One Gift Became a Dynasty

No polydactyl cat is more famous than the six-toed cats of the Ernest Hemingway Home and Museum in Key West, Florida. The story, as the museum tells it, begins with a ship's captain named Stanley Dexter, who gave the author a white six-toed cat named Snow White sometime in the 1930s. Hemingway, who was fond of cats throughout his life, kept her on his Key West property, and Snow White's descendants have lived on the grounds ever since. Today roughly 40 to 50 cats live at the museum, and about half of them are polydactyl — all believed to descend from that original gift.

The association became strong enough that "Hemingway cat" is now a widely used nickname for any polydactyl cat, even one with no connection to Key West at all. Maine Coons have a similar, if less celebrated, reputation: early New England farm stock included a meaningful number of polydactyl cats, and some breed historians have argued the wider front paws may once have offered a slight practical advantage for walking on snow, though this is folklore more than established science.

A short look at the history behind the "Hemingway cat" nickname and the polydactyl mutation itself.

Does It Cause Any Problems?

For the overwhelming majority of polydactyl cats, the extra toes are entirely harmless and the cat never knows anything is unusual about its paws. A few practical things are worth knowing as an owner, though:

• Extra nails need extra attention. An inner "thumb" toe often doesn't touch the ground, so its claw doesn't wear down naturally the way the others do. Left untrimmed, that claw can curl around and grow into the paw pad — check it during routine nail trims the same way you'd check a dewclaw on a dog.
• Wider paws, no real mobility issue. Despite how unusual the paw looks, polydactyl cats walk, run, climb, and use a litter box completely normally. Some owners report their poly is unusually good at manipulating objects with its paws, a popular but unverified bit of cat lore.
• It is not the same condition as "twisty cat" syndrome. A separate and much rarer condition, radial hypoplasia, causes shortened or malformed forelimbs along with wide, splayed paws that can resemble extreme polydactyly. Unlike ordinary polydactyly, radial hypoplasia can cause genuine mobility problems, and breeding for it is considered an animal-welfare concern by major cat fancier organizations. Plain polydactyly, with normal-length limbs and simply extra digits, does not carry this concern.

Breed Standards and Everyday Cats

Most polydactyl cats are not a distinct breed at all — they're ordinary domestic shorthairs or longhairs that happen to carry the gene, which is why the trait turns up unpredictably in random-bred cat populations far more often than in pedigreed ones. The major registries (CFA, TICA, and others) do not recognize polydactyly as a standard trait in most established breeds and will disqualify it from the show ring in breeds where a strict paw conformation is part of the standard, even though the cats themselves are perfectly healthy. A handful of informal "American Polydactyl" breeding programs exist specifically to preserve and standardize the trait, but it has never become an official, widely recognized breed.

The Bottom Line

Polydactyly is one of the more charming quirks of cat genetics: a single dominant mutation, inherited unpredictably, that can turn an ordinary paw into something that looks almost hand-like. Outside of routine nail care for toes that don't touch the ground, a polydactyl cat needs nothing different from any other cat — and if Hemingway's cats are anything to go by, the trait has a way of sticking around in a family for generations.