Polydactyly in cats 

Polydactyly, coming from the Greek, means “having more than the normal number of fingers or toes.” It occasionally occurs in humans, as well as including dogs, mice, horses, and other animals, but is much more common in cats. The gene for polydactyly is thought to be incompletely dominant, so that a kitten with one parent having the gene may or may not be polydactyl.  

Polydactyl cats are also known as “mitten cats," "thumb cats," "Boston thumb cats," and “Hemingway cats." The reasons will soon become clear!

Cats normally have five toes on the front paws and four on the back; with polydactyly, they may have as many as seven, with the largest number ever reported being eight per foot. Sometimes the extra digit is one very prominent thumb; sometimes the cat’s extra toe or toes give the paw a fan-shaped appearance. It is more common to have extra toes on the front feet, but they can be on the back feet as well. A cat will never (or rarely, depending on the source) have extra toes on the back feet without also having them on the front.

Polydactyly is considered an anomaly, not a deformity, in cats; some people feel the extra “thumbs” are actually opposable, helping these cats to grip their toys.

It is thought that Maine coon cats were the first to show the trait. Up to 40% of Maine coons used to be polydactyl; the trait has since been bred out of them. (For more info about Maine coons, read my article: Maine coons ).

Polydactyl cats are more common in the Eastern United States, which is the beginning of the explanation of the term “Hemingway cats.” The first polydactyly cats were probably brought over from England in colonial times. Sailors considered the feature lucky; they thought the extra toes gave the cat better sea legs as well as better mousing abilities. A ship’s captain probably gave Ernest Hemingway, a cat lover, a polydactyl cat as a gift, and that cat then passed along the gene to future generations.

Hemingway had a home on a small island off Key West, Florida. With him lived a colony of about 50 cats, about half of them polydactyl. Today, you can visit Hemingway’s island home, now the Ernest Hemingway Museum and Home; a colony of about 60 cats still lives there, protected by the terms of his will. At least some of those cats are descendents of Hemingway's first cat; after many years of inbreeding, presumably all the cats there now carry the polydactyly gene, with yet about half showing the trait.

Some breeders are trying to bring back polydactyly in Maine coons, and several new breeds are being developed with this trait. This is probably a bad idea. While polydactyly is usually no more than a curiosity, and perhaps an advantage in gripping ships’ decks, catching mice, and playing with cat toys, it may lead to complications without human intervention.

A polydactyl cat may have extra claws that he cannot sharpen normally. The claws may grow into the paw pad, cutting it and possibly causing infection, or the claw may grow outward, leading to snagging. Your polydactyl cat’s claws may need to be clipped regularly or surgically removed by your veterinarian. Note that this is a departure from the normally hard-and-fast rule against declawing cats.

Please see www.declawing.com for more information on declawing and alternatives.

Another option is to outfit your polydactyl cat with Soft Paws [link to product], vinyl nail caps that fit over your cat's clipped claws. Be sure to specify that your cat is polydactyl when ordering, in case of special size considerations.

Hemingway often named his cats after movie stars and characters in his books. If you’re thinking of adopting a “Hemingway cat” and would like to give it a “Hemingway name,” just do an Internet search for “Hemingway cat names.” And remember to give your cat’s claws the extra attention they need.

(C)Lisa J. Lehr