Who doesn’t love a glistening golden palomino, or an exotic blue-eyed pale horse? I sure do! But how do those colors happen if horses only produce red and black pigment, as we learned in the first post in this series? Glad you asked, because there is a very good answer!
When a horse is a color other than black, chestnut, or bay, it means that a genetic mutation has acted to dilute the horse’s coat. There a lots of these mutations, and we call these dilutions. The cream dilution is arguably the most well known and popular. It is abbreviated CR if the horse carries the gene, and cr in its recessive non-cream form.
Cream is a partially dominant gene. That means that unlike the other dominant genes we have learned about, a horse who is heterozygous for cream (CRcr) will look different than a horse that is homozygous for cream (CRCR).
First, let’s talk about the CRcr colors. In its heterozygous form, cream only acts on red pigment and dilutes it to a golden color. It essentially takes all the red out of the horse’s coat and leaves it a shade varying from cream to dark golden tan. A single cream gene does not act on black pigment, so a bay horse’s points stay black, along with any black hairs scattered throughout the coat. A black horse does not show cream at all (Black hair scattered through a red or bay-based coat is called “sooty” and no genetic control for it been discovered yet). Sometimes a single copy of cream will also cause the horse’s eyes to be a bit lighter than a non-dilute horse’s – sort of a dark amber, rather than chocolate.
Palomino horses are the result one copy of cream acting on a chestnut base. They are genetically ee CRcr. Cream dilutes their red manes and tails to white and their bodies to gold. Palominos are strikingly lovely horses. Their golden coats make them very popular and HOP has rescued quite a few over the years.
Stirrat is a beautiful example of a palomino. He even has a touch of “sooty”. See his dapples and how his legs are a little darker? If he didn’t have a cream gene, he would most likely be a dark liver chestnut.
Stirrat’s cute little daughter, Sansa, is a palomino just like her father. She’s a lighter palomino without a sooty appearance.
When a bay-based horse has one copy of cream, it is called a buckskin. Buckskins are genetically E_A_CRcr. Their bodies are the same range of shades as palominos, but their points stay black. It’s true that a good horse is never a bad color, but buckskin is my favorite of the diluted colors. Golden coats, shiny black manes, what’s not to love? HOP has had a few of these lovelies, as well.
Bug and Calli are buckskins, although Bug has something else going on that we will cover in a future post.
A closer look at Calli’s adorable face shows us the dark amber eyes that some cream horses have.
When a black horse has one copy of cream, it’s called a smoky black. They are E_aaCRcr. But because one copy of cream will only work on red pigment, a smoky black horse cannot be differentiated from a regular black horse. Their phenotype is the same, and you can only know a black horse has cream if you do a genetic test or if its offspring are cream.
That’s a LOT of information about heterozygous cream horses! But hang on, we aren’t done with cream yet.
We still have the homozygous cream dilutes, or double creams. Fortunately there’s not a lot to them. Two copies of cream gives a horse blue eyes, pink skin, and a very pale cream coat. Black horses with two copies become smoky cream (E_aaCRCR), bays become perlino (E_A_CRCR), and chestnuts become cremello (eeCRCR). Their phenotypes are nearly identical and it is impossible to tell them apart without genetic testing.
Dane is a double cream dilute. His skin is pink, his eyes are blue, and his coat and hair are pale cream. He could be any of the three double cream dilute colors. We simply cannot be sure just by looking at him (he would need genetic testing for us to know for certain which). I think this little fellow is just lovely, and his striking pale color makes him even more so.
That’s all on the Cream Gene!
Next time we will talk about dun.
The read the first in this series, visit “What Color is My Horse?”
(This fantastic informative piece is penned by Liz E., a dedicated HOP volunteer and equine color aficionado)