It's gross, it's hot, and it's super humid outside. I love warm weather, but this isn't warm, it's just humid. So, in order to procrastinate more, I'm FINALLY going to get to appaloosa genetics.
Appaloosa coat colors are controlled by multiple genes. First there's the "main" gene, LP. This is what makes the mottled skin, the striped hooves, the white sclera (eye), and causes the horse to progressively gain more white hairs over time in its coat - roaning.
Some people will say that their horse doesn't roan. That's not true. ALL appaloosa horses will roan to SOME extent. A few roan only minorly, but they still do roan. It's simply the nature of the gene. Of course, the more white a horse has to start with, the less it roans, because, it's already near the end of its limits!
The second "gene" isn't actually a gene, it's a group of genes that get lumped into one. Those are the pattern genes. There are about 30 different genes suspected (but not yet proven) to affect the amount of "dense white patterning" that a horse is born with.
The third "gene" is also not a gene, but a group of genes. These are the modifier genes. We've already discussed a few of these with face and leg markings. Coat color also counts as a modifier. Most modifier genes have a primary purpose, and only modify appaloosa markings as a secondary thing.
As you can see, appaloosa coat patterns are one of the more complex patterns in the horse world. Of course, this is why I love them so much... they make me think. When predicting appaloosa patterns, you have to take EVERYTHING into consideration. Base coat color, face and leg markings, resistance to roaning in the parents, white pattern shown at birth, ranges of pattern enhancement, and of course the obvious chances of inheritance of LP.
And every one has their favorite patterns such as:
And of course, there's a variety of roans. These are horses that were born with characteristics only, but no pattern:
The dam, not the foal in the last picture. As you can see, the level of expression varies greatly. I have some that are my favourites, from leopards, to big splotchy roans, and of course I love big blankets with big splotchy roaning.
Because Appaloosa genetics gets rather complicated, I will be using a lot of pictures. Most of these horses are mine, or ancestors of mine. I'm pulling pictures out of the archives, so not all will be pretty poses... forgive me for that.... and some will be baby pictures of horses that are now mature.
Oh, and I'll warn you ahead of time. Appaloosa genetics makes most people's head's hurt!
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.