A Note about Sugarbush Draft Horses
I see it over and over again, and no matter how many times it's said, it's still wrong. "Sugarbush Drafts are just an Appaloosa Draft Cross". Uh.... no. The Sugarbush Draft Horse was a breed created many years ago in Ohio. While the initial cross was made using Percherons to Appaloosas, in the many generations following, the breed has been solidified into a consistent type. Saying these horses are "just" a draft cross makes as much sense as saying that AQHA horses are "just" a Thoroughbred cross, American Cream Drafts are "just" a dilute Belgian, or that Morgans are "just" a grade.
Thursday, July 22, 2010
White face and leg markings
I'm not sure a study has ever been done to determine who is correct. We do know that face and leg markings are inherited, and that sabino (which is actually a group of genes) causes certain characteristics to be seen on face and leg markings. We also know that other genes affect face and leg markings as well, such as splash and Overo (OLWS). I think that much of the sabino debate is due to people wanting their horse to have some "cool" pattern, and the recent acceptance of excessive white in many breeds from Arabians and Thoroughbreds to the white rules in AQHA.
Certain types and locations of these markings are considered normal. Socks, blazes, stars, and stockings are all easily accepted markings on a "solid" horse. Then you have something like this filly shows. Her blaze is irregular, and even has a hole in one area of it, and a displaced section of white on the opposite side. This is Soliloquy, a Stonewall Sport Horse filly whose name I usually shorten to Soli. Her dam has both sabino and splash (black mare shown below), while her sire carries sabino. Soli's markings show mostly traits of sabino, but there are a few signs that show she is also carrying splash.
Ever wonder how to tell the difference?
Sabino markings tend to be pointy. Sharp areas on blazes and socks that point towards the belly. Also, white on the lower lip is a big indicator of sabino. The chestnut shown below has classic sharp sections around his nostrils, and the black has obvious white on his lower lip. Both horses are suspected to have minimum sabino.
Then there are leg markings. Sabino leg markings are pointy (see a pattern here?) and usually are higher towards the belly. The only horse I have that shows this carries both sabino and splash, but I think you can get the idea. Yes, she's also very pregnant in this picture.
As for those "other effects" well, genes like sabino, splash and frame (commonly called frame white, or overo) have an effect on other white patterns. These are called "enhancer genes". It is a well documented fact that horses with excessive white face and leg markings tend to show more white in their patterns as well, both pinto and appaloosa patterns.
Base coat color also plays a role. Dominant extension (E) is a suppressor of white patterns, while recessive extension (e) is an enhancer. What does that mean? Well, a horse that is Ee will have a smaller blanket then a horse that is ee, and a horse that is EE will have an even smaller blanket then the heterozygote. Agouti is an enhancer gene, and it's effects have been documented even when the gene is hidden. A horse with the genome ee AA will have a larger pattern then a horse with the genome ee aa. To make it somewhat easy to remember, we often say that black supresses the most, then bay (a little suppression and a little enhancing), then chestnut.
These suppressors and enhancers will become important when I talk about appaloosa color genetics. There are MANY genes that have a suppression or enhancing role in color, and not all of them are known. In some cases we know that certain family lines, or breeds have "suppressors" but we don't know exactly what causes it.
This is why genetics tends to get so confusing. There's so much going on at the same time, and genes can have multiple roles. In many cases people ignore the supression and enhancing traits, and simply work on the basic genetics of the coat color, but if you want to breed for a very specific pattern (such as minimal paints, or leopard appaloosas) then these additional effects must be taken into consideration.
Many of the same genes that cause face and leg white markings can also cause pinto patterns with a "louder" expression. Splash is most commonly seen as face and leg white, but is most commonly associated with high chrome horses. Frame is ususally expressed as a pinto pattern, but can "hide" in face and leg markings only. These pinto patterns being expressed as only "normal" white markings are often refered to as "minimal" (insert type of pattern). Such as a minimal splash, or minimal frame.
Now, for your test......
What pattern genes would you suspect this foal of having?
There are 3 patterns at work here. Lets see who can guess!