This post first appeared on July 6, 2011
I don’t know the original meaning of the Spanish word sabino, but it should have been “mimic”. The sabino patterns often mimic the characteristics of the other patterns.

Leopard complex is the gene that functions as the master switch for the various appaloosa patterns. One of the well-known characteristics of the leopard complex gene is visible sclera, or eye whites. The eye above belongs to Dottie, a pasture mate of my own appaloosa mare Sprinkles. Dottie is a loud chestnut leopard. (Her rump was used in the comparison shots in the manchado post.) It isn’t unusual to see white in the corner of a horse’s eye, especially if they are looking at something. What makes appaloosa eye whites different is that they are visible on both sides of the eye even when the horse is not looking at anything in particular. I took this picture when Dottie was resting under a shade tree, and until I started pestering her with the camera all she wanted to look at was the backs of her own eyelids.

It isn’t the most practical of characteristics. I often forget that the whites of my mare’s eyes don’t actually indicate the direction of her gaze. I once walked forward to see why she was fearful, only to see the whites on the front, too.  She wasn’t looking at boogie men in the woods beyond us, but behind at the snake draped across both her hind hooves.

It’s also not a characteristic unique to appaloosas, although they do show it most consistently. It shows up on a fair number of horses that carry one of the sabino patterns.

This guy was even more sleepy than Dottie, but the sclera is still visible on both sides of the eye.

This one had very visible sclera on both sides, and is a good illustration of why this characteristic is often called “human eye”. It is harder to see in the photo of his other side because of the shadows, but that one does show how these eyes still show directional gaze even if it is just a subtle change.

Sharing this trait does not usually pose much of a problem when it comes to identifying patterns because appaloosas and pintos are not usually hard to tell apart. It takes an unusual set of circumstances to make that difficult, but that is exactly the case with the Old Kladruber. Visible sclera is seen in a lot of Kladrubers, and historical documents suggest that this has been the case for at least the last 100 years. But because the Kladruber has been bred for rapid – and complete – greying (quite the opposite from yesterday’s horse!), and because facial vitiligo is common, the clues for sabino and leopard complex are muddled. The same could be said for some of the Iberian breeds, which might explain why appaloosas have occasionally cropped up there.

I’ll close with a shot of Dottie’s other eye, which oddly enough does not have visible sclera at all.