Polydactyly (Feline) — Cat Glossary

Polydactyly

Polydactyly (from Greek: poly = many, daktylos = finger) — a genetic condition in which a cat is born with more than the normal number of toes on one or more paws. Caused by a dominant mutation on the Shh (Sonic hedgehog) signalling pathway. Largely benign. Also called "Hemingway cats" after the famous colony in Key West, Florida.

The genetics

Feline polydactyly is caused by a dominant autosomal mutation — a cat needs only one copy of the mutated gene to express extra toes. It affects the Shh regulatory region (the ZRS enhancer), which controls limb bud development. The molecular basis was described by Lettice et al. (2007) in PLOS Genetics, in a paper that also illuminated limb development genetics more broadly.

Because it is dominant, a polydactyl cat mated with a normal cat produces roughly half polydactyl offspring. Homozygous (two copies) polydactyly is theoretically possible but rarely seen — the condition is almost always heterozygous.

Normal vs polydactyl toe count

PawNormalTypical polydactyl

Front left5 toes6–7 toes

Front right5 toes6–7 toes

Back left4 toes4–5 toes

Back right4 toes4–5 toes

Total18 toes20–24 toes (typically)

The Hemingway cats

Ernest Hemingway received a six-toed white cat named Snow White from ship captain Stanley Dexter, and the descendants of that cat have lived at the Hemingway Home and Museum in Key West, Florida continuously since the 1930s. The property's roughly 40–50 cats are protected as a National Historic Landmark and cared for by a full-time staff. They are one of the best-known examples of a polydactyl colony.

Extra nails, extra attention. The innermost extra toes on polydactyl cats often resemble a thumb and carry a nail that does not make ground contact. These nails grow in a curve and can embed in the paw pad if not trimmed. Check all extra toes monthly and trim as needed — or ask your vet to show you the first time.

Is it a welfare concern?

Generally no. Polydactyly is not associated with increased rates of lameness, joint disease, or shortened lifespan. It is classified by International Cat Care as a largely benign anatomical variant. The only routine management requirement is nail care for the extra digits.

In contrast, other paw-related genetic mutations in cats (such as twisty cat / radial hypoplasia) do cause significant welfare concerns and should not be confused with polydactyly, which is a separate and unrelated condition.

Frequently asked questions

Is polydactyly harmful to cats?

In most cases, no. Polydactyl cats live normal, healthy lives. The extra toes do not cause pain or mobility problems in the vast majority of cases. The main practical concern is nail care: extra toes — especially dewclaw-like inner toes — can have nails that curl inward if not trimmed regularly, potentially embedding into the paw pad. Regular checks by an owner or vet prevent this. International Cat Care outlines the basic care requirements.

How many extra toes can a polydactyl cat have?

Normal cats have 18 toes (5 on each front paw, 4 on each back paw). Most polydactyl cats have one or two extra toes per affected paw, typically giving them 6 or 7 toes on the front paws. The Guinness World Record for the most toes on a cat was held by a cat with 28 toes, though such extreme cases are rare. The genetics are described in Lettice et al. (2007) in PLOS Genetics.

What is the Hemingway connection?

Ernest Hemingway was given a six-toed cat by a ship's captain, and the descendants of that cat still live at the Ernest Hemingway Home and Museum in Key West, Florida. The roughly 40–50 cats on the property are a National Historic Landmark attraction. The term "Hemingway cat" is now used colloquially for any polydactyl cat, though the condition appears worldwide and predates Hemingway's association with it.

Is polydactyly a breed?

No — polydactyly is a trait, not a breed. It can appear in any breed of domestic cat. The Maine Coon historically had a high prevalence of polydactyly (believed to be advantageous for walking on snow), though deliberate selection has reduced it in show lines. The GCCF (UK) and most cat registries do not recognise polydactyly as a standalone breed.

Does a polydactyl cat need special care?

The main difference is nail maintenance. Extra toes — particularly the innermost, thumb-like toes — have nails that may not wear down naturally. Check all paws weekly and trim nails monthly, or as needed. If a nail appears to be growing toward the pad, have a vet check it. Otherwise, polydactyl cats need exactly the same care as any other cat.