Thursday, December 18, 2008
Breeding Dogs for Intentional Defect
Sam, winner of ugliest dog contests 2003-2005.
All of the winners of the world's ugliest dogs contests have been Chinese Cresteds.
Why is this?
Well, it's more than the lack of hair on the dog's body, or the odd placement of what little hair that does exist.
It's also the horrible condition of the teeth, and the fact that the dogs appear to have a hard time keeping their tongues in their mouth.
All of this is by design if not quite by intent.
Elwood, winner of ugliest dog contest 2007.
Rascal, winner of ugliest dog contest 2002.
You see, when folks are breeding hairless dogs, they are breeding for a specific genetic mutation of the FOXI3 gene, which controls both the development of coat and teeth in all hairless breeds.
Because the gene that controls hairlessness also controls teeth formation, hairless Chinese Cresteds generally have missing teeth, deformed teeth, or misplaced teeth, and it is fairly common for hairless dogs to end up completely toothless at some point in their lives.
As a result, the American Kennel Club standard for this made-in-America breed says that the "Hairless variety is not to be penalized for absence of full dentition."
Chinese Crested dogs, Mexican Hairless (Xoloitzcuintle), and Peruvian Hairless all share the same no-hair and poor-dentition gene mutation, and all are believed to be descended from a single-dog mutation which occurred in the New World some 4,000 years ago.
While hairless dog breeders are intentionally breeding defective dogs for canine ectodermal dysplasia (CED), the same condition in humans is considered a fairly serious problem.
Actor Michael Berryman was born with Ectodermal Dysplasia : A nice man.
As with hairless dogs, humans born with ectodermal dysplasia have malformed teeth and extremely sparse hair, and a higher-than average chance of having misshaped facial features and skin and eye abnormalities. This is because, as the National Foundation for Ectodermal Dysplasias (NFED) notes, "The ectoderm contributes to the formation of many parts of the body, including the skin, sweat glands, hair, teeth, and nails. During embryonic development, these and/or other parts of the baby’s body, including the lens of the eye, parts of the inner ear, the fingers and toes, or nerves, among others, may fail to develop normally."
This is not to say that all hairless Chinese Crested dogs look like Zuul the devil dog in Ghostbusters anymore than to say that all humans with ectodermal dysplasia look as startling as Michael Berryman.
Most hairless Chinese Crested look like the dog below -- some with a little more hair, and some with a little less.
That said, most have teeth issues, and the breed has a relatively short average life -- just over 10 years -- quite a bit less than the number typically stated in the all-breed literature.