Hyper-specific Topic: Horse Color Genetics

Let’s go off on a tangent, shall we? A warning first: If you don’t care about horses at all, skip this post. As all five of you who read this blog may know, I am a fan of all things equine. And when I am a fan of something, I learn about it. So, I’ve learned a little bit about horses over the years. One pet peeve of mine is when professional horse-people, especially people who breed horses, seem to know nothing about them. I mean, c’mon folks. One of the many, MANY places in which ignorance raises its ugly head is in the prediction of a foal’s color or coat pattern. I’m tired of people bragging about how their buckskin stallion “throws 75% color in his babies!” ARG! There is a scientific way of determining the future baby by simply observing the color genetics of the sire and dam! You just have to get your horse DNA tested. Now, this will cost money, but so does successful, responsible horse breeding. Now, in breeding there is always going to be a healthy degree of chance, but we can reduce the role of chance by understanding the wonderful world of genetic inheritance. Follow me along on a magical journey with equine science!

The Terms! Before we advance, we should all know some basic coat color/pattern terms. For this post, I shall focus on the cream gene because of its popularity. The cream gene is known as a color modification gene for its tendency to modify color! Specifically, it dilutes color. Red turns to gold, gold turns to white, white turns to a super-massive black hole and destroys the Universe. Still with me? Great. The cream gene is responsible for those lovely golden palominos we see during the Rose Parade. Thank you, cream gene, you’re doing a great job! And now we have been introduced to the cream gene.

Two other important terms are homozygosity and heterozygosity. If a horse is homozygous for the cream gene, it will have two copies of that gene. If a horse is heterozygous for the gene, it will just have one copy. These words may sound scary, but the idea behind them is simple. If heterozygosity is a hamburger, then homozygosity is a double-double. Not all color-related genes are this simple, but we have to start somewhere.

One thing that makes the cream gene easy to deal with is the fact that it is an incomplete dominant gene. If a horse inherits the gene, it will show. Below are examples of the cream gene in horses:

Palomino: This is a popular coat color that happens when a horse with a red (chestnut/sorrel) base coat inherits one copy of the cream gene. Notable palominos include Trigger, Mr. Ed, and Barbie’s horse.

Buckskin: This is the less-famous Baldwin brother of horse color. Like palominos, buckskin horses have golden coats, but instead of a white mane and tail, theirs are black. The buckskin color is what happens when a bay (brown with black points) based horse has one copy of the cream gene. Just to confuse you further, a bay horse is considered to have a black-based coat. This is due to the presence of the aguti gene, which is dominant over the black gene and turns the coat brown (while leaving the mane and tail black). So a buckskin is a black horse that is a bay horse that is a gold horse. Notable buckskins include; Buttercup (Trigger’s less-famous stable mate), and Cisco (from “Dances with Wolves”).

                                                     (Photo attributed to: Tierpfotografien at de.wikipedia)

Cremello: When an otherwise red-based horse gets a double helping of the cream gene (both parents must have passed the gene on), it appears white with pinkish skin and blue eyes. This horse is now homozygous for the cream gene and will always pass the gene to its offspring. Breeding to a cremello is a nearly sure-fire way of producing a cool-colored foal. Cremello + chestnut = palomino (always). Cremello + bay = buckskin, chestnut, or smoky black (appears black). Because more variables are involved with bay horses (aguti gene, black gene, etc), there is a wider variance of color in this mating. Some notable cremellos include: …I can’t think of any right now.

Perlino: A perlino horse is also double for the cream gene, but has a black (or bay) base coat. Like a cremello, it also appears white with pink skin and blue eyes. When bred to a bay or black or chestnut, the resulting foal can be palomino, buckskin, or smoky black. I am also having a hard time finding famous perlinos. 

Here is a super-fun site that allows you to predict foal color: http://www.horsetesting.com/CCalculator1.asp

Here is a visual chart that is also fun: http://www.horsecolor.com/dilutions/cream/foal_chart.htm

And here is a chart depicting the cream gene: http://www.horsecolor.com/dilutions/cream/color-chart.htm

                                            I am not a perlino or a cremello, I carry the unicorn gene.