Polydactylism Cause

Most cats are born with five digits on each front paw and four on each back paw. Some cats, however, are born with more than the normal number of digits. This condition is called polydactylism, which means "many fingers." Polydactylism (or polydactyly) is an inherited genetic condition that causes no physical disadvantages in most cases. Polydactyl cats became famous as the preferred pets of writer Ernest Hemingway and President Theodore Roosevelt. Their unique history has made them desirable pets.

  1. Genetics

    • Polydactylism is a genetic trait that probably resulted from a mutation in one or more genes, according to PetPlace.com. Several different genes are responsible for polydactylism, and there are several different mechanisms of inheritance. Sometimes, the gene for polydactylism is dominant, resulting in polydactylism in up to 50 percent of offspring. If both parents carry the gene, the trait will present in 75 percent of offspring. There is also a recessive form of the gene for polydactylism. This form only presents 25 percent of the time, and both parents must carry the recessive trait in order for it to appear in offspring.

    Types

    • There are two kinds of polydactylism, according to Messybeast.com. Pre-axial polydactylism involves extra digits on the inside of the paw. Post-axial polydactylism involves extra digits on the outside of the paw. Post-axial polydactylism is extremely uncommon.

    Breeding

    • Historically, polydactyl cat breeding has involved a large amount of inbreeding, since breeding two unrelated polydactyl cats will not always produce polydactyl offspring, but breeding related polydactyls always will. This practice eventually led to genetic birth defects and resulted in health problems in many of the offspring. According to Maine Coon Polydactyl International, this history of inbreeding has resulted in a poor reputation for the health of the Maine coon polydactyl cat population, even though the majority of today's Maine coon polydactyls are not inbred and are statistically just as healthy as other breeds.

    History

    • According to the Cummings School of Veterinary Medicine at Tufts University, the first documented case of polydactylism was recorded in 1868. Polydactyl cats were called "ship's cats" and were considered good luck by sailors who thought their extra toes gave them better balance aboard ship. Populations of polydactyl cats proliferated in Yarmouth, Massachusetts, and Halifax, Nova Scotia, along the shipping trade routes of the 1800s. In Maine (the Maine coon cat is often polydactyl), residents believe polydactylism evolved to help cats walk on the snow. Despite all the folklore, there is no scientific evidence that polydactylism confers any specific advantages to cats.

    Uncommon Variation

    • Most forms of polydactylism are harmless and affect only the paws of the cat; however, a deformity known as radial hypoplasia is associated with a specific and rare genetic variety of polydactylism. According to PetPlace.com, radial hypoplasia results in a malformed radius, one of the long bones of the forepaws. This deformity makes it difficult for cats to walk on their front legs. Cats with radial hypoplasia are known as "twisty cats" or "pixie-bobs," and in some cases are bred intentionally for their peculiar appearance and movement.