Thursday, September 1, 2011

Guess the Genotype #19

How about guessing the genotype of this dog?

Image is from Wikimedia Commons under a creative commons license

She's black, right? Well, not so fast. She actually has tan points! They're muddy and a bit hard to see, but they're definitely there. Genetically, this dog is basically the same as the Xolo that I talked about before. I'll repeat myself:

As I said, this dog is tan pointed. This is most obvious on the lower legs and the little tan "pips" above the eyes. The amount of tan on dogs with tan points can vary greatly, and the markings on this dog remind me a bit of a Labrador retriever mismark I once saw. It is very possible that this dog also carries recessive black, which is the form of black seen in the German shepherd breed. I am going to assume she does, which means she is ata tan point carrying recessive black.

As with nearly every other German shepherd out there, this dog has a mask (very very rarely you will see a GSD without a mask). Masking will either eliminate or nearly cover the tan on the face of a dog with tan points. Since the masking gene is so prevalent in the breed, it's almost guaranteed that this dog is EmEm masked.

I do wonder about the possibility that this dog could have a copy of the brindle gene. The gene was once present in the breed, though it was though to have died out. Though there is a small possibility that it is carried by the recessive black dogs, I really doubt that this dog would have a copy of the gene. Unless she's actually part Dutch shepherd, that is! However, this dog is listed as a purebred German shepherd and as such I will treat her as one. That means she must be kk non-black or brindle.

This dog does have a little white on her chest, but there are very few German shepherds out there (the "Panda shepherds") that have any white spotting genes other than solid. As such, this dog must be SS solid with residual white.

So, that is ata EmEm kk SS or masked black and tan with residual white.


  1. Sure about that?

    My understanding is that recessive black is on the A locus, denoted as "a".

    There is a dominant black that's located on the K loci, denoted as "K".

    My thinking is that she's an atat K- but showing something called "bad black". For whatever reason, the black fails to cover up completely. It's referred to as seal in some of the other breeds.

  2. I do very much see your point, and in some breeds this could be a very reasonable conclusion. However, there is one issue. I am not an expert on German shepherds, but I have seen a lot of information on the genetics of the breed's colors. All of the sources I have seen say the same thing: in the German shepherd breed, the form of black that is seen is recessive black. This is confirmed from breeding data.

    It's actually fairly easy to figure that sort of thing out. Let's say you have a black dog and breed it to a non-black and all of the puppies end up non-black; then you breed siblings from that mating together and they produce blacks (hypothetically, of course, since that is never a good idea), it would have to be recessive.

    In dominant black, black dogs can only come from other blacks. Black dogs can and will sometimes pop up in lines of German shepherds that haven't produced blacks in generations and as such the form of black seen in the breed has to be recessive.

    This page has pretty good information on the inheritance in the breed.

  3. *If* dominant blacK, K, absolutely does not exist the GSDs, I'm inclined to think the dog is an at a and for some reason the at did not completely dominate over the effects of a. This is based on the hearsay that tar heels and black on the toes are an indication of carrying a.

    Though I'm admittedly not as well versed in the GSD breed, I'm still wondering if dominant black may be lurking in some GSD lines. The Belgian Groenendael ended up as having both dominant black and recessive black for instance.

    The easiest test to rule it out dominant black without test breeding is to just send a buccal sample to UC-Davis for K testing. :-)

  4. Well, that is also possible, but I don't know that it is necessarily true (even though I did assume that this dog carries recessive black). Breeds such as the Manchester terrier (either size) are known for their tan points being abnormally black and that is a breed that breeds true for tan point. So, no recessive black there. It may be one of those cases where unknown modifiers are at work? In a lot of cases, a breed will breed true for a specific phenotype pertaining to the amount of tan on a black and tan, etc.

    I guess that could be possible in lines that only breed for black, however as far as I know there has never been a non-black German Shepherd puppy born from a black/black mating that was anything other that white (which is recessive red, so is a totally different story).

    As for genetic testing, just remember that it has only been feasible for a few years now, and before that people figured out a lot by doing test-matings such as the one I mentioned earlier. I do think there should be more research into cases like this, though, since we do have the technology and it is growing cheaper and cheaper all of the time. It is quite possible that one day we can identify the numerous unknown modifiers that do such things as control the amount of white in dogs, outside of the already known S locus. There is so very much variety seen in the amount of white on dogs, and I do suspect that there are at least some genetic components that go into it besides S, si, sp, and sw.

  5. While not in possession of the vast scientific genetic knowledge as you all have, I have a dog who looks very similarly and whose genetic testing revealed him to be German shepherd and Canaan dog.