Sunday, October 9, 2011

Guess the Genotype #26

Can you guess this dog's genotype? What about his breed? The image angle is part of the challenge.

Image provided to me by J. Burns of Ghostfire Photography, and is copyright to him

Here's a couple more pictures of Petey (taken at a boarding facility). Click for the full size images. 

Petey is a pit bull mix who actually has a nearly completely white head!  This is a bit odd, since otherwise his white is fairly minimal. From what I've seen, this is actually a fairly common occurrence in pit bulls, bulldogs, and mixes of similar type, where the dog has far more white on its head than would be expected when looking at the amount of white on its body. This is likely due to selective breeding for this phenotype. The genetics behind facial white is not very well understood, but the variation seen (both this extreme, and the opposite extreme of color-headed white) is likely due to the action of plus and minus modifiers. Plus modifiers would allow more white to occur, while minus modifiers would make less white occur. With the addition of selective breeding, this would explain how some breeds (or sometimes certain lines in a breed) have achieved fairly consistent amounts of facial white. Anyway, on to Petey's likely genotype:

This dog clearly has tan point, and as such must be atat tan pointed. I do not see any evidence for recessive black in pit bulls, and as such it is highly unlikely that Petey carries this color.

In pit bulls, it is common for dogs to be called "red-nosed" or "blue-nosed," which simply means that they express one of the dilutions that turn black in the coat to liver or blue, and which will affect the skin pigment as well. Petey appears to be a nice, deep black, however it is quite possible that he carries one of the color dilutions. Due to this, I am going to claim that he is Bb non-liver carrying liver and Dd non-blue carrying blue.

The only other gene that is likely to be affecting his phenotype is the spotting gene. Though he has so much white on his head, if you ignore his face he is actually collared Irish white. Though it is possible he is carrying a piebald gene, since piebald is also common in pit bulls, I don't think it is likely. I am told he doesn't have any white past his shoulders except for white toes. So, I do not believe that he carries piebald. That would make him sisi white collared Irish.

So, that would be atat Bb Dd sisi or white-faced collared Irish black and tan (carrying liver and blue).


  1. You know, I'm no good at these games. But I thought this one might be a good candidate for your series:

    I've got some answers if you need a cheat sheet. I have no vocabulary for these discussions on canine genetics, but it's always interesting to see what you come up with.

  2. He's a handsome fellow! I've actually seen him already. I hope to adopt a BRAT basenji one of these days, so I check their site about once a week or so. I might just use him. We shall see. :)

    For the most part, I am fairly familiar with the color genes that are found in basenjis. I blame years of research on the breed. I fell in love with them about eleven years ago, and have been preparing myself for owning one when I have the means.

    One of the most fascinating basenjis I have ever seen was one that was up on BRAT several years ago. She was a heavy sable with blue eyes! That was the one and only time I've ever seen one with blue eyes.

  3. Hehe, I figured you were a bit of a basenji fan based on some of the folks that pup up in your blogroll. Were you also intrigued by the Wimauma pups in Florida? Now I thought THAT group would have made a most interesting case study -- I think most of them have homes now.

    Yes, this guy is a very pretty-looking fellow. Sable isn't normally seen in modern B's, I believe? Not sure if it's seen in Africa. One hint about this guy: his BYB bred him from "questionable" pedigrees...

  4. I was indeed. They were quite unusual in appearance, which fascinated me. Either they have some mixed ancestry, or it was their tough life that made them so unusually large.

    Oh really? I think I see it. He does seem oddly terrier-ish in the face. I wonder if he might have some mixed ancestry too? As for sable, if you look through the BCOA African Stock Project offspring page there are more sables from those lines than there seem to be otherwise. Here's a few (though most are said to have "saddles," they are actually sable):

    There has been some DNA testing for color in some of the Africans, and apparently recessive red and clear sable both occur in the breed. Clear sable always presents the possibility of producing a non-clear sable.

  5. Okay, see, unless you hit me with the Obvious Stick, I wouldn't have taken those saddles as "sables." I don't know the genetics of how that plays out. I guess that's why I read your blog.

    If you get any warmer about the little red rescue, we're going to have to treat you for burns.

    (Poor neglected Petey, btw... all these comments and not a bit about him!)

  6. Well, the saddle coloration has also occurred in those lines, but far less often. It's usually fairly easy to tell the difference, especially if you know what the puppy looks like when it was born. Saddled dogs are always born appearing to be black with tan points (like Airedale terriers), but the black fades with age into a very distinctive pattern. Here's a saddled basenji, showing the fading: puppy, adult. The saddle pattern is also genetically black and tan, which can be determined with genetic testing. Sable, in contrast always looks about the same at birth, and some red will be visible where you can't see any in a black and tan or saddled tan puppy. Sometimes, only time will tell whether the black in a sable will stay or clear up.

    Haha! The basenji face is pretty distinctive. Curious, very curious. He also looks a bit big. Is that just my imagination?

    Anyway, I'm sure Petey doesn't mind. :)