Understanding What Causes Polydactyly in Cats
Polydactyly, the condition of having extra toes, is a fascinating and harmless genetic trait that appears in many domestic cats. Polydactyl cats are often affectionately referred to as
"mitten cats" or "Hemingway cats" and are known for their unusually shaped paws. While the phenotypic expressions may vary, the root cause lies in a
dominant gene mutation affecting toe development.
Genetic Origin of Polydactyly
The most common cause of polydactyly in cats is a mutation in the
ZRS regulatory region, which controls the
sonic hedgehog (SHH) gene. This gene plays a crucial role in limb development during embryogenesis. A single copy of this mutated gene, inherited from one parent, is sufficient to manifest the trait in offspring. Thus, only one parent has to carry the gene for kittens to potentially exhibit polydactyly.
How Polydactyly Manifests
Typically, cats have 18 toes: five on each front paw and four on each back paw. In polydactyl cats, extra toes can appear on one or more paws:
- Preaxial polydactyly — extra toes on the inner (thumb) side of the foot
- Postaxial polydactyly — extra toes on the outer (pinky) side
- Mesoaxial polydactyly — rare, extra toes in the middle of the paw
Some cats might have up to seven toes per paw, and exceptional cases, like those of cats named Jake and Paws, have up to 28 total toes.
Geographic and Breed Distribution
Polydactyl cats are not rare, but they are more commonly found in certain regions and breeds:
- East Coast of the United States, especially Massachusetts and Key West, Florida
- Southwest England and Wales
- Parts of Canada
In terms of breed prevalence:
- Maine Coon — Historically, up to 40% showed polydactyly, though less common today
- Pixiebob — Frequently exhibits the trait
- American Polydactyl — Includes various cats with this gene, but not a recognized breed
Physical and Functional Impacts
In most cases, extra toes do not affect a cat’s mobility. However:
- Some extra digits may consist only of soft tissue and lack full bone structure
- These toes can be more vulnerable to injury or infection
- Owners should watch for signs of discomfort or limping
If an extra digit causes pain or repeated problems, surgical removal might be necessary. As part of routine care, owners should:
- Regularly check between toes for debris or infection
- Trim all claws, especially those that don’t touch the ground and may overgrow
- Consult a veterinarian if swelling, pain, or unusual gait is observed
Historical and Cultural Significance
Polydactyl cats have a rich historical connection to maritime culture. Sailors favored them, believing their
broader paws helped with balance on ships and their
extra digits made them better mousers.
Famed author
Ernest Hemingway received a six-toed cat from a sea captain, which led to the nickname "Hemingway cats." His former residence in Key West now houses many of the descendants of his original polydactyl cat.
Myths and Misconceptions
It's a common misconception that polydactyl cats are rare or inherently more valuable. While they may be less common in some areas, the trait itself is not unusual and does not increase market value unless linked to breed or lineage.
Conclusion
Polydactyly in cats is a
genetically inherited condition caused by a dominant mutation affecting limb development. It usually presents as an endearing physical trait rather than a health concern. With proper foot care and monitoring, polydactyl cats lead healthy, happy lives and continue to charm people with their unique toes and storied history.
