Tuesday, August 23, 2011

Guess the Genotype #17

Can you guess the genotype of this dog? Nope, I'm not playing a trick on you. It's actually fairly simple to figure out.

Image is from Wikimedia Commons under a creative commons license.

The first thing to remember when looking at a hairless dog, is if it has any hair, pay attention! This dog's hair is pale, but you can see hints of black hairs on the ear and hints of red on the neck. So, what does this mean?

Even though the dog only has a few black hairs, it must be sable. At first glance I thought the dog was a recessive red, but a recessive red dog will never have any black in its coat. As far as I am aware, the only other allele on the A locus that exists in the Chinese crested breed is tan point, though it seems to be unusual. If you look at powderpuffs, or the Chinese crested with fur, it is the best way to guesstimate what genes are seen in this breed. I believe this dog is most likely AyAy sable. So, why is the dog's body mostly dark? Because the skin of a sable dog very often will be.

The light patched of skin are caused by the spotting gene. If you were to shave a dog that is piebald, the white areas would be growing from skin that either lacks pigment or has a few spots of dark pigment. This is why dogs with white will so often have a spotted belly, and why hairless cresteds will so often have pink skin with dark spots. I suspect this dog is Ssi solid carrying Irish, producing residual white.

Of course, there is also a gene that causes the lack of hair in the hairless breeds. In nearly all of these breeds if not all, the gene is dominant and lethal in the homozygous form. As such, this dog must be heterozygous. I am unaware of whether the gene has previously been given a letter distinction, but I will call it Z. So, this dog would be Zz hairless.

So, that is AyAy Ssi Zz or hairless sable with residual white.


  1. Good answer. Except the fancies threw a wrench in your assessment:

    It's a zz.

    It's not uncommon for Chinese Crested owners to shave them or nair them. In fact, the ones who are breeding "true hairless" are usually outside the show ring. Sad, eh?

  2. Oh, yes, I didn't think about that.

    Do you know anything about the differences between hairy hairless, true hairless, and powderpuff? From what I have seen, they usually only shave the "hairy hairless" dogs which usually have patches of bald skin on places like the belly, and the ones exhibited as powderpuffs have a full coat of fur. I'm wondering whether the hairy hairless dogs have the hairless gene or not since they still will have bald patches.