Limitations, clarifications and some questions

Kila2

I am still playing catch-up with the Splash Project page, with more homozygous horses (like this Paint mare owned by Julia Lord) to add, as well as links to some interesting negative tests. I did not realize that an unexpected week away would put me quite so far behind!

Until I am caught up, there are a few important bits of news. A few horses have surfaced that have tested positive for one of the other versions of splashed white, SW2. One can be seen here. Reports are that she is SW1/SW2. It has also been rumored that the Quarter Horse stallion Colonels Smoking Gun carries the SW2 version. Whether his is the only line, or if there are others, is not yet known. So far I have not heard of a horse that has tested positive for SW3. Hopefully some of those will turn up soon.

It is interesting to note that the linked SW2/SW1 mare has somewhat less white on her body than the horses that have been testing homozygous for SW1. That will be something interesting to watch for among the horses that have a combination of two different versions. Even though their basic look might be the same, as has been reported, there may yet be visual differences that people good at pattern identification may see.

And that brings me to my own limitations. I have said that I am a phenotype researcher; I look at and analyze the visual appearance of horses. I look at a lot of horses, and I study family groups and trends within them, but I am not a molecular researcher. I have had what amounts to a crash course in the molecular end of this subject in the last ten years or so, because it has become increasingly relevant if one wants to grasp the current research. But it goes without saying that at that level, there are gaps in my knowledge. And I will likely never be as comfortable with that part as I am with determining tonal and pattern differences. So be aware, when reading this blog, that I am first and foremost an artist by trade.

I try to keep that limitation in mind. It is very important to me that this blog not perpetuate bad or misleading information. I have tried to simplify concepts presented here, because most readers are either artists or breeders or owners, but simplification itself can be misleading. I’ve been told that this is the case with the “one slot” explanation for KIT mutations. I was fortunate that someone with far more background in the technical end of genetics was able to point me to some relevant research, and hope to post a clarification in the near future. For the moment, though, let me throw down a marker that the subject of KIT mutations is more complex than that.

I also have questions about the nature of alleles, which others have expressed in other venues. The question I have had is whether or not these different versions of mutations (like SW2 and SW3) occur independently of one another, or does the original mutation get altered as some point. That is, was there one splashed white (presumably SW1 since it is most common and occurs in very old breeds) that changed into SW2 and SW3? Or did completely new mutations occur in the same general area and affecting some of the same functions? Since each dominant white mutation was like that – separate instances of similar mutations – we know that the latter scenario can happen. Is that what usually happens?  Knowing this might tell us something about where to expect – or perhaps where not to expect – the less common (and perhaps as-yet-unidentified) versions of splash. I hope to send out some queries along those lines, and report back what I find.

, ,

11 Responses to Limitations, clarifications and some questions

  1. Maridi Pletcher February 14, 2012 at 11:17 am #

    I wonder if the deafness found in some splash whites is only in homozygous individuals?

  2. Sue Stewart February 14, 2012 at 12:14 pm #

    Colonel’s Smoking Gun (AQHA/APHA — double registered), aka Gunner, is currently one of the most popular reining horse sires. He *seems* to pass on the “splash look” far more frequently than 50% — I’m not knowledgeable enough in those bloodlines to know an actual statistic. There are *many* examples at Tim McQuay’s (where Gunner stands), and they’re visible all over in “reining horse land”. There are several right down the road from me at another name-brand reining trainer — at least one of those is a grandget of Gunner. If he’s SW2, there’s a lot of it in the world! :)

    • Caroline February 14, 2012 at 12:22 pm #

      One thing to keep in mind is that they do seem to cross a bit of Mr Gun Smoke on Gunner, which will help get very white individuals. I’ve seen several that are Gunner/Trashadeous (Trash being out of Miss White Trash by Mr Gun Smoke) – Gunnatrashya being one of the better known, though a lesser-marked one.

      • The Equine Tapestry February 15, 2012 at 6:54 am #

        It’s all speculation at this point, but if Gunner is a source for SW2 he could be SW1/SW2 rather than SW2/n. He’s also used in a breed where there are other white patterning genes like sabino (or a lot of things we currently call sabino for lack of more precise terms), and those are probably factoring in as well.

  3. Caroline February 14, 2012 at 12:14 pm #

    The revelation that that Wimpys Little Step/Gunner mare is SW1/SW2 carrier is quite interesting. Also that Gunner is supposedly a SW2 carrier. It makes me curious as to which version of splash Mr Gun Smoke carried, as well as wonder just where the splash came in at. I knew that Wimpys Little Step had some white, and that his sire, Nu Chex to Cash had even more – I just didn’t suspect splash! The only Nu Chex to Cash offspring I’d come across that I suspected of being splash carriers were out of Mr Gun Smoke-bred mares, and never seemed to have all that much white on them. An inverse of the mare above (Gunner/Wimpys Little Step cross) with amazing markings: http://www.mvnreininghorses.be/breeding.html

    A lot of the foundation horses I’d figured (apparently incorrectly in some cases!) to have been sabino, mainly due to the fact that a lot of them that had a lot of white were from predominantly Thoroughbred lines, or anyway, the Thoroughbred lines were the ones that were known. This just adds to my desire to have a full collection of the AQHA stud books, and far more pictures, in general, of the old horses!

    I’m excited to see more stock horses tested, to not only see which versions of splash exist, but to start getting an idea as to which lines produce which version.

    • The Equine Tapestry February 15, 2012 at 6:56 am #

      I have been hopeful of that, too. There have long been suspected splash lines, but hopefully the tests will help nail down some of the specifics. I am also hoping that by process of elimination, it will start to tell us more about the non-splash white patterns, too.

  4. Leah February 14, 2012 at 12:39 pm #

    That Paint mare is gooorgeous! I think that Classic Splash White is one of the most attractive pinto patterns.

  5. Liz February 14, 2012 at 3:29 pm #

    Interesting that Gunner is apparetly SW2. I’m curious if maybe that means SW2 is linked to deafness (as I’m pretty sure he’s deaf?), rather than homozygous white, as previously thought.

  6. jacqueline Goertz February 14, 2012 at 9:58 pm #

    No one has mentioned this, but has anyone thought of the Arabian having splash? I’m seeing people calling them splash white. I always thought the Arabian only had one white pattern which was some sort of sabino, but these horses have blue eyes and they’re making really do look like splash. They’re also all pure Arabians so it’s not some genes from some other breed

    • The Equine Tapestry February 15, 2012 at 7:02 am #

      I sincerely hope that they are being tested. There has been at least one family that to me looked suspiciously like splashed white, though it has not yet produced what to me is a clear-cut classic splash pattern on a purebred.

  7. Maridi Pletcher February 21, 2012 at 5:41 pm #

    Coat Color results for Erica’s Take a Look At Me(DT29595):

    Splashed White SW-1 Result:
    SW1/SW1 – Horse has two copies of the SW-1 mutation.

    Its official! Baldy is homozygous sw1