This post first appeared on July 18, 2011
Amrita Ibold of Sweet Water Farm shared this photo of her green-eyed perlino Akhal-Teke, Kegas. This photo shows the darker golden ring around his eye, which gives his eye a green, rather than a blue, appearance.

Since starting this blog, I have gotten a number of emails from owners of homozygous cream dilute horses saying that their horses did not have truly blue eyes. Perhaps the most striking of these has been the Morgan stallion Amberfields Desperado. Many people have questioned whether or not a horse like that could even be a cremello, but he is an 18 year-old breeding stallion with a large number of foals on the ground. His eyes may be well beyond the norm for the color, but he has by all reports bred like one. This past weekend I met someone with a double-dilute from him, also with the same greenish eyes. When I get pictures, I will share those, too.

At the same event I ran into an unrelated cremello. This guy was a rescue, so nothing was known about his background. He did have blue eyes, but they had brown striations around the outer edge of the iris, as well as small flecks of brown inside.

Seeing these horses has made me wonder if the rule that homozygous creams are blue-eyed is absolute, or if there is a little more variety. And if that is the case, what causes the eye color to be different?

We already know that human eye color – the iconic subject for teaching about dominance – is not actually as simple as once thought. There are a number of genes in human beings that modify eye color. If there are numerous genes influencing eye color in human beings – even changing them over time – what is to say that the same might not be true of other animals?