Polydactyl cat

One of the polydactyl cats at the Ernest Hemingway House in Key West, Florida. This particular cat has 26 toes, two extra on each paw.

A polydactyl cat is a cat with a congenital physical anomaly called polydactyly (or polydactylism, also known as hyperdactyly), a type of cat body type genetic mutation that causes the cat to be born with more than the usual number of toes on one or more of its paws. Cats with this genetically inherited trait are most commonly found along the East Coast of North America (in the United States and Canada) and in South West England and Wales.

Nicknames for polydactyl cats include "boxing cats", "mitten cats", "mitten-foot cats", "snowshoe cats", "thumb cats", "six-fingered cats", "Cardi-cats", "Hemingway cats", and "double-pawed cats." Two specific breeds recognized by some but not all cat fancier clubs are the American Polydactyl and Maine Coon Polydactyl, and named regional populations include the Boston thumb cat, Cardi-cat, Ithacat, and Vermont snowshoe cat.

Occurrence

The true polydactyly is a congenital abnormality, genetically inherited as an autosomal dominant trait of the Pd gene with incomplete penetrance.

Normal cats have a total of 18 toes, with five toes on each front paw and four toes on each hind paw; polydactyl cats may have as many as seven digits on their front and/or hind paws. Tiger, a Canadian polydactyl cat with 27 toes, was recognised by Guinness World Records as having the highest number of toes on a cat.^[1] (However, unofficially, this title goes to Mooch, a 28-toed American polydactyl cat from the New England state of Maine. Mooch's owners, Bob & Becky Duval, have submitted evidence to the Guinness Book of Records.^[2]) Various combinations of anywhere from four to seven toes per paw are common, and the number of toes on either the front or rear paws is typically the same. Polydactyly is most commonly found on the front paws only, it is rare for a cat to have polydactyl hind paws only, and polydactyly of all four paws is even less common.

The nickname "double-pawed cat" is a misnomer since there is a specific double paw condition, although this condition may be interrelated with polydactyly.^[3]

Feline radial hypoplasia (see squitten) is a mimic of polydactyly and is considered a severe condition. Radial hypoplasia may cause the formation of extra jointed toes, but it is not a result of the Pd gene normally associated with polydactyls. It thus does not cause the "mitten cat" or "thumb cat" condition where the extra toes occur separated from the normal ones just like a dewclaw, usually associated with an additional pad which makes them look like an underdeveloped foot sticking out near the base of the normal toes. Rather, radial hypoplasia-related extra toes are immediately adjacent to the normal ones, giving the cat overly large, flat feet — colloquially known as "patty feet" or "hamburger feet". Though this looks less serious than true polydactyly (as the feet appear "normal" apart from having one or two extra toes), breeding such cats will eventually result in severely crippled offspring. Cats used in polydactyl breeding programs can be screened by x-ray for indicators of radial hypoplasia, and cats suspected to have radial hypoplasia should not be used for breeding.

History and folklore

The condition seems to be most commonly found in cats along the East Coast of North America (in the United States and Canada) and in South West England, Wales and Kingston-upon-Hull. Polydactyl cats have been extremely popular as ship's cats. Although there is some controversy over whether the most common variant of the trait originated as a mutation in New England or was brought there from Britain, there seems to be agreement that it spread widely as a result of cats carried on ships originating in Boston, Massachusetts, and the prevalence of polydactyly among the cat population of various ports correlates with the dates when they first established trade with Boston.^[4][3] Contributing to the spread of polydactyl cats by this means, sailors were long-known to especially value polydactyl cats for their extraordinary climbing and hunting abilities as an aid in controlling shipboard rodents. Some sailors also considered them to be extremely good luck when at sea.

Genetic work studying the DNA basis of the condition however indicates that many different mutations can all lead to polydactyly^[5] and since samples from the UK and USA were shown to possess different mutations it seems likely that these cats have originated multiple times independently, rather than spreading from a single origin.

Nobel Prize–winning author Ernest Hemingway was one of the more famous lovers of polydactyl cats, after being first given a six-toed cat by a ship's captain. Upon Hemingway's death in 1961, his former home in Key West, Florida, became a museum and a home for his cats, and it currently houses approximately fifty descendants of his cats (about half of which are polydactyl). Because of his love for these animals, "Hemingway Kitty Cat", or simply "Hemingway Cat", is a term which has come to describe polydactyls.

Some sources state that these cats are rare in Europe because they were killed as witches' familiars,^[4] but other sources indicate that they are quite common in southern Britain.^[3]

Caring for a polydactyl cat

This type of polydactyly is not life-threatening and usually not even debilitating to a cat. Some polydactyl kittens initially have more difficulty in learning to walk than normal animals; however in some cases polydactyly appears to improve the dexterity of the animal. For example, a common variation with six toes on the front paws, with two opposing digits on each (comparable in use to human thumbs), enables the cat to learn and perform feats of manual dexterity generally not observed in non-polydactyl cats, such as opening latches or catching objects with a single paw.

Cats usually "file down" their nails, thereby removing the outer layer. However, some of the claws of polydactyl cats are in awkward positions, so they are not able to trim them down by scratching. If proper trimming is not done, then these claws could grow into the cat's flesh and cause infection.

Breeding

American Polydactyl cats are bred as a specific cat breed, with specific physical and behavioral characteristics in addition to extra digits.^[6]

The American Polydactyl is not to be confused with the pedigree Maine Coon polydactyl. The polydactyl form of the Maine Coon is being reinstated by some breeders.^[7]

A particular strain of polydactyl cats native to Ithaca, New York is known as the Ithacat. Polydactyls are very common in the Cardigan area of Wales, where they are known as "Cardi-cats."

Gallery

• 

  Right front paw of male polydactyl cat

• 

  Opposable "thumb" on male polydactyl cat

• 

  Hind dewclaw on male polydactyl cat

• 

  Extra toes on front paws, female polydactyl cat

• 

  Extra toes on back paws, female polydactyl cat

• 

  "Thumb" on female polydactyl cat

• 

  "Thumb" on Female Polydactyl Kitten

• 

  Appearance of "mittens" due to extra toe

• 

  Domestic female polydactlyl cat, with opposable thumb visible.

• 

  "Mitten paws" on female domestic shorthair kitten.

• 

  Opposable "thumb" on two-year-old female polydactyl cat.

• 

  Front left paw of male polydactyl cat.

• 

  Female polydactyl. Extra toes on front and hind legs.

• 

  Male kitten with 23 toes.

References

1. ^ Fat Cat, Inc. - Your Cat Magazine Articles!
2. ^ http://www.cat-world.com.au/cat-world-records
3. ^ ^{a b c} "Polydactyl Cats (Part 1)". http://www.messybeast.com/poly-cats.html. Retrieved 2007-01-20. 
4. ^ ^{a b} "Is it true many New England cats have extra paws because Boston ships' captains considered them lucky? Or may it be true that they were better at catching mice than normal cats?". The Straight Dope. 1999-06-29. http://www.straightdope.com/mailbag/m6toecat.html. Retrieved 2007-01-20. 
5. ^ Lettice, L A; A E Hill, P S Devenney, R E Hill (1995-02). "Point mutations in a distant sonic hedgehog cis-regulator generate a variable regulatory output responsible for preaxial polydactyly". Human Molecular Genetics 17 (7): 978–985. doi:10.1093/hmg/ddm370. PMID 18156157. http://www.ncbi.nlm.nih.gov/pubmed/18156157. 
6. ^ "American Polydactyl". http://www.centralpets.com/animals/mammals/cats/cat5776.html. Retrieved 2007-01-20. 
7. ^ The History of the Polydactyl Maine Coon

• Chapman, VA; Zeiner, FN: The anatomy of polydactylism in cats with observations on genetic control Anatomical Record 141:205-217, 1961
• Danforth CH: Heredity of polydactyly in the cat. Journal of Heredity 38: 107, 1947
• Danforth CH: Morphology of the feet of polydactyl cats. American Journal of Anatomy 80:143, 1947
• Jude, AC: Cat Genetics, 1955
• Robinson R: Genetics for Cat Breeders, Mar 1977
• Sis, RF; Getty, R: Polydactylism in cats Veterinary Medicine and Small Animal Clinician 63:948-951, 1968
• Todd, NB; Jones, TC: On independent assortmant of dominant white and polydactyly in the cat Journal of Cat Genetics 1:16-17, 1964
• Vella, C; Shelton LM; McGonagle J; Stanglein TW: Robinson's Genetics for Cat Breeders and Veterinarians, Butterworth- Heinemann Ltd (19 Aug 1999)
• Wenthe, M; Lazarz, B: A case of atavistic polydactyly at the hind limb of a cat [German] Kleintierpraxis 40:617-619, 1995
• Wittmann, F: Polydactylism in a Cat Praktische Tierarzt 73:709, 1992

External links

• Hemingway Home Museum, Key West Florida, cats webpage
• Article on polydactylism in cats in New England
• Polydactyl Cats Photo Gallery online
• Images of polydactyl cats
• Maine Coon Polydactyl Tracking Database and Resource
• Owner's appeal over cat's 26 toes