Guess the Genotype #22

Can you guess Ebon's Genotype?

If you didn't notice from the pictures, Ebon is actually not solid black, but instead has tan hairs sprinkled all over his lower legs, as well as some on his face. The placement of the tan is almost identical to that seen in tan pointed dog. So, what's behind it? It is possible that it's "sun burning" that is often seen in black dogs, however that is generally more noticeable on the dog's back and rear and may only be present during certain times of the year. Ebon rarely gets sunburning and when he does it occurs on his hips and only lasts for the summer months. Also, there is more tan on the inside of his legs than the outside, which doesn't fit with the idea of sun exposure causing the tan to appear. I suspect that the constant tan on his legs is somehow genetic in nature.

There are really only two possibilities if it is genetic. Either he is actually a mismarked black and brindle with extremely heavy striping, or he is a "bad black" or "seal." I suspect that the latter is true. In "bad black," the dominant black gene somehow does not fully cover the agouti locus, causing a sort of bronzing effect. It has been confirmed that "seal" dogs seen in such breeds as the Italian greyhound have at least one copy of the dominant black gene. The actual genes that produce this bronzing effect haven't yet been found.

I suspect that Ebon is atat tan pointed at the Agouti locus. If he is in fact a "bad black," this could very well explain the placement of the tan. Also, of all of the rare mismarks seen in the Labrador retriever breed, tan point does appear to be the most common, with or without brindle striping. It is quite possible that Labradors may have the tan point gene fixed in the breed, which would explain why you see tan pointed mismarks but never sable.

Ebon is also Bb non-liver carrying liver. I know this because his mother is a chocolate Labrador and thus genetically homozygous for the liver gene.

I also believe that Ebon is Eme masked carrying recessive red. His father is a yellow Labrador and thus homozygous for the recessive red gene. In a similar thought process that led me to thinking he has the tan pointed gene, I believe he also has a copy of the masking gene. Though there are a few tan hairs on his muzzle, there are far fewer than would be expected if he did not have a copy of the mask gene. Masking is also seen in mismarked Labs.

Now we come to the "bad black." Genetically, they have at least one copy of dominant black and as such if Ebon is bad black he would likely be KK black. It is also true that the dominant black gene is very close to being fixed in the Labrador breed, so in all likelihood this would be true anyway.

So, that's atat Bb Eme KK or black with bronzed legs (carrying liver and recessive red).

Here are some websites with pictures of mismarks in Labradors: one, two, three