POLYDACTYL MAINE COONS: WHAT POLYDACTYLY REALLY MEANS
Updated: Sep 12
The extra toes are the obvious part. The biology, inheritance and extraordinary variation behind them are considerably more interesting.
At first glance, polydactyly seems almost self explanatory. A cat has more toes than usual, therefore it is polydactyl. That is correct, but it barely begins to describe the trait.
In the Maine Coon, polydactyly is an inherited developmental characteristic that can produce remarkable variation in the structure and appearance of the paws. One cat may have a single additional digit. Another may have several. The characteristic may appear on the front paws, the hind paws, or all four. Even two Maine Coons with the same number of toes can have paws that look completely different.
What we see on the outside is the finished result of events that began much earlier, while the limbs were forming before birth.
What actually counts as polydactyly?
Most domestic cats have eighteen digits. There are five on each front paw and four on each hind paw. A polydactyl cat is born with additional digits beyond this usual arrangement.
Yet counting toes tells only part of the story.
Research examining polydactyl Maine Coons has shown considerable variation not simply in digit number, but also in the arrangement of the digits and in the underlying structures of the paw. This is why polydactyly should not be imagined as an ordinary paw with an extra toe simply attached to the side.
The architecture of the foot itself may be different.
Some polydactyl paws have the familiar mitten appearance, where an additional digit sits apart from the main group and can resemble a thumb. Others have a broader arrangement often described as a patty paw. Some cats have almost perfectly mirrored feet, while others show differences between one side and the other.
There is no single polydactyl paw.
There is a spectrum of expression.
The biology begins before the toes exist
The formation of a limb during embryonic development is remarkably organised.
Cells must receive precise instructions about where different structures should develop. Among the signalling systems involved is one associated with a gene called Sonic Hedgehog, commonly abbreviated to SHH.
Its unusual name conceals an important biological role.
SHH helps regulate the pattern of the developing limb. Research into polydactyly in domestic cats has identified changes within a regulatory region that influences SHH activity during this stage of development.
Certain genetic variants can alter where that signalling occurs within the developing limb, changing the usual pattern and allowing additional digits to form.
This is one reason the familiar expression the polydactyl gene is rather too simple.
The visible result may be an additional digit, but behind it is an alteration in the regulation of limb development.
The genetics are not identical in every Maine Coon
The genetic story becomes even more interesting when Maine Coons are examined specifically.
Researchers studying polydactyl Maine Coons from breeding populations in Europe, Canada and the United States found that a previously identified genetic variant was present in some polydactyl cats, but not in all of them.
The known variant could therefore explain part of the population, but not every polydactyl Maine Coon studied.
The researchers concluded that polydactyly in the breed is genetically heterogeneous.
In practical terms, that means the same visible characteristic can arise against different genetic backgrounds. Two cats can both unquestionably be polydactyl without necessarily sharing the same known molecular explanation.
There is something particularly interesting about that from a scientific perspective.
The paws may appear to give us an obvious answer, while the genetics underneath them remain more complex.
Research has explained a great deal about feline polydactyly.
It has not explained everything.
An inherited characteristic with variable expression
Polydactyly in the Maine Coon has been shown to behave as a dominant inherited characteristic in the populations studied.
That does not mean every cat expresses it in exactly the same way.
The number of additional digits can vary.
Their position can vary.
The paws affected can vary.
The overall shape of the foot can vary considerably.
This is known as variable expression.
Research has also documented incomplete penetrance in Hw associated Maine Coons, meaning that some cats carrying this variant did not visibly express polydactyly.
That distinction matters because the relationship between genetic information and the visible appearance of the paws is not always as simple as a basic inheritance diagram might suggest.
The detailed genetics deserve an article of their own because the subject is frequently reduced to simple percentage calculations that do not tell the whole story.
For now, the important point is that polydactyly is inherited, but its appearance is not uniform.
More toes do not mean a better paw
The dramatic appearance of some polydactyl Maine Coons can make toe count seem more important than it actually is.
It is not a competition.
TICA recognises considerable variation within the Maine Coon Polydactyl standard. Additional digits may appear on the front feet, the hind feet, or both. Mitten and patty forms are recognised, and there is a permitted maximum of seven toes on an individual foot.
Crucially, the standard does not give preference simply because one cat has more additional toes than another.
A cat with exceptionally large or dramatic paws is not automatically a better example of a polydactyl Maine Coon.
The structure, balance and quality of the whole cat still matter.
The feet attract attention because they are unusual, but they should not dominate every judgement made about the animal carrying them.
What does a polydactyl paw feel like to live with?
For most owners, the day to day difference is surprisingly ordinary.
There are simply more digits and more claws to know.
Studies examining polydactyl Maine Coon paw structure have found considerable anatomical variation without identifying an apparent detrimental consequence for welfare in the populations studied.
That is reassuring evidence, but it does not remove the need to look at the individual cat.
An additional claw may sit in a position where it receives less natural wear. Some digits can be tucked closely beside another. Others may sit separately from the main row of toes.
The practical answer is not complicated.
Owners should know the arrangement of each paw, identify every claw and include all of them during normal claw checks.
Good paw care begins with understanding the individual structure in front of you rather than assuming every polydactyl foot is the same.
A historic characteristic of the Maine Coon
Polydactyl Maine Coons are sometimes presented as though they are the product of a recent desire for increasingly unusual cats.
They are not.
Polydactyly has a documented historical association with the Maine Coon population and was present long before modern breeding programmes began deliberately preserving particular paw types.
There is, however, an important limit to what can be stated as fact.
The precise origin of polydactyly within the early Maine Coon population is not known.
Various stories have developed around the trait, particularly involving working cats, ships, snow and supposed advantages provided by broader feet.
Some of those stories are repeated so frequently that they can begin to sound like established history.
They are not established history simply because they are familiar.
There is a difference between a plausible story and documented evidence.
Where the historical record ends, a serious account of the breed should say so.
The known history of the Maine Coon is interesting enough without improving it through folklore.
The Maine Coon Polydactyl today
Within TICA, the Maine Coon and Maine Coon Polydactyl are recognised within the same Breed Group, with the polydactyl cat carrying the MCP designation.
TICA accepted the Maine Coon Polydactyl for Championship competition in 2015.
That formal recognition is important, but the philosophy within the breed standard is equally significant.
Balance and proportion remain fundamental.
A Maine Coon is assessed as a complete animal.
Its head, profile, muzzle, ears, body, boning, musculature, coat and overall balance do not become secondary simply because the cat has extraordinary feet.
This is perhaps the most sensible way to understand polydactyly within the breed.
It is significant.
It is distinctive.
It is not the whole cat.
What polydactyly can tell us
A polydactyl paw tells us something about inherited variation and the development of the limb.
It does not tell us whether the cat has been responsibly bred.
It does not tell us about cardiac screening, genetic testing, hip health, pedigree planning, temperament or early socialisation.
It cannot tell us whether two breeding cats were thoughtfully matched.
Those questions remain separate.
For breeders, polydactyly can be preserved without allowing it to become the sole objective of a breeding programme.
For prospective owners, the unusual paws can be appreciated without allowing them to distract from the questions that matter to the welfare and quality of the complete animal.
A kitten should never become more desirable simply because the toe count is impressive.
The visible part of a much larger story
Perhaps the most interesting thing about the polydactyl Maine Coon is how deceptive the apparent simplicity of the trait can be.
We look at a paw and see an extra toe.
Behind that toe is embryonic development, inherited variation, regulatory genetics and a range of anatomical expression capable of producing remarkably different feet within the same breed.
Even now, the genetic explanation is not complete.
Known variants account for some polydactyl Maine Coons, but research indicates that they do not account for every case.
There are still questions to answer.
That uncertainty does not make the subject less authoritative.
Quite the opposite.
Good science distinguishes between what has been demonstrated, what remains possible and what is still unknown.
The polydactyl Maine Coon does not need exaggerated stories to make it fascinating.
The biology is fascinating enough.
Buba Ayers
Founder & Breeder, Tycoon Manor
Sources and further reading
Hamelin A, Conchou F, Fusellier M, Duchenij B, Vieira I, Filhol E, et al. Genetic heterogeneity of polydactyly in Maine Coon cats. Journal of Feline Medicine and Surgery. 2020;22(12):1103 to 1113. DOI 10.1177/1098612X20905061.
Hamelin A, Begon D, Conchou F, Fusellier M, Abitbol M. Clinical characterisation of polydactyly in Maine Coon cats. Journal of Feline Medicine and Surgery. 2017;19(4):382 to 393. DOI 10.1177/1098612X16628920.
Lettice LA, Hill AE, Devenney PS, Hill RE. Point mutations in a distant Sonic Hedgehog cis regulator generate a variable regulatory output responsible for preaxial polydactyly. Human Molecular Genetics. 2008;17(7):978 to 985. DOI 10.1093/hmg/ddm370.
The International Cat Association. Maine Coon Breed Group, MC and MCP. Official Maine Coon and Maine Coon Polydactyl breed standard and breed information.
