Around the fall of 2002, messybeast.com caused a stir with its page on winged cats. The link (http://www.messybeast.com/winged-cats.htm) was passed around in message boards and blogs, and most people shrugged off the photos and stories there as a hoax. Afterall, the web is filled with examples of freakish feline humor, like bonsai kitten and tubcat. However, the disorder messybeast.com focuses on on the winged cat page, feline cutaneous asthenia (or FCA for short), is indeed real, and documented in many veterinary journals. In plain English, cutaneous asthenia means "skin weakness". Other animals experience similar disorders, which are generically known as collagen dysplasias. In humans, the disorder is known as Ehlers-Danlos Syndrome, and people with this condition were the "India rubber men" of carnival freakshows. Cattle, sheep, and dogs are also subject to the disorder. In sheep and cattle, it's more well know as dermatosparixis.

The disease is genetic, and two forms of it have been described in cats, each apparently caused by a different gene(s): one in which is a recessive trait, another in which it is dominant. The recessive version of FCA is caused by a deficiency of an enzyme called procollagen terminal peptidase. The lack of this enzyme causes collagen fibers to be unable to form their usual, tubular shape. They appear misshapen and twisted. The dominant version of FCA causes a disorganization of the fiber bundles. Animals with two copies of the dominant FCA gene probably die before birth. Both forms of the disease are very rare, and they both result in an animal being born with very loose, fragile skin.

So much as petting a cat with FCA can result in the skin stretching and even tearing. It is often advised that the cats be declawed, to prevent them from hurting themselves. The disorder can also affect joints and blood vessels, and animals can die from a sudden rupture of their arteries.

So, how's this related to winged cats? Well, while some of the photos of winged cats may be doctored, some reports hoaxes, and in other cases the "wings" mentioned may actually be mats of fur, there are certainly some cases of winged cats that fit the usual picture of FCA. For example, there is a report of a winged cat shot in Sweden, in 1949. Professor Rendhahl, a member of the State Museum of Natural History, examined the cat, and concluded that the wings were actually large flaps of skin. How many of the cases of winged cats were actually reports of FCA is hard to tell...however, it would be wrong to say (as some websites report) that most cases of winged cats are descriptions of the disorder. FCA is very rare, and while winged cats aren't exactly a dime a dozen either, many of the cases are obviously fakes or of cats with matted fur.

In the end, what we have in FCA is a very interesting condition that is just one of the main explanations behind cases of "winged" cats. It is real (though rare), incurable, hereditary, and not at all the sort of thing you would wish upon your pet. Messy Beast tying the winged cat stories to FCA sensationalized it, but that does not change the fact that it is a recognized and documented veterinary disorder.

Sources:
http://www.inno-vet.com/journals/vetderm/980901/06.htm
http://www.lclarkecushingvmd.com/showpracfaq.cfm?FAQID=108&Private=0
http://www.abvetline.com.au/vetline/linkstmp_alpha.stm?dis_id=159&species=cat
http://www.vetpathology.org/cgi/reprint/36/6/603.pdf