Albinism in Horses

To follow up with the promised post after the last one, I of course have to talk about albinism in horses. To recap, albino is when there is no pigment in the skin; all genes that control color are off.

There are quite a few curiosities on the subject, including a simple fact that will surprise you: albinism has never ever been proven in horses.

While you may be able to Google quite a few images of horses that appear albino, there has never been a case in which they weren't able to prove it was something else. The horses above came up in the search, as well as the ones below.

As mentioned in the last post, red eyes only sometimes indicate albino, and there are several other things besides that would. However, with horses, there is no picture I can find of a horse with red eyes that doesn't look photo shopped, or when you look close up are actually blue eyes surrounded by pink skin.

According to various sources, blue eyes in horses is not exactly lack of pigment, and is as close to non-pigmented eyes as you can get, but again there isn't no pigment.

The most commonly mistaken color for albino is cremello, because of the very light-colored skin that often is pink with blue eyes. However, using the method of deciphering albino as in the last post, albino has no base color, and there is no pigment behind it. Cremello is a chestnut horse with two cream genes, so it would indeed have some pigment. Other double-cream horses (perlino, smoky cream) may be categorized among cremello in being mistaken for albino.
If you were to take the tiniest bit of red paint, and then add a dose of white, it makes pink. If you add even more white, it becomes light pink. Even if you keep adding white to the original red, the paint will never be truly white, no matter how much you put in.

One of the closest things to albino scientifically is dominant white. Dominant white is considered to be a white-spotting genes, along with patterns such as tobiano and frame overo. The main difference with dominant white is that it often shows up as one, huge spot, entirely covering the body and blotting out the under color. Did you notice that last sentence? 'The under color'. There is a color under there that they can pass on.

Dominant white can be expressed in many different ways, even within each specific mutation. It isn't always predictable, and because of that it isn't a fool-proof way to describe as albino. It seems like most of the time, it leaves the eyes their original brown color, although there are some cases of white. That would depend on the specific mutation.

Fully-expressed sabino is similar to dominant white, except that sabino never causes blue eyes, leaving the eyes dark.

So, I guess the underlying question is: why? Why has albino never been proven in horses? Why would horses be the exception?

Albino means there is no pigment whatsoever, and they never have any color to pass on. With all these genes, the horse also has a color underneath. The only way for a horse to be albino would be that somehow, the gene that causes pigment (extension) wouldn't be working.

Extension is the only gene that causes pigment. All the rest of the genes I speak of are simply instructions, or a way to lighten what was already there. Isn't that interesting?

For albino to happen, extension would have to find a way to not work. Because it is a dominant gene, one or two copies produces black pigment. In recessive form, it causes red pigment. That doesn't leave any option open for no pigment, see?

In the whole history of horses, we haven't found a way for it not work as of yet. Albino hasn't happened yet, that doesn't mean it can't. Extension would have to find a way to be missing entirely from the genome, but how when both parents have it boggles my mind. Colors, and the way they work, and the way we percieve them is constantly changing.