photo: Cheryl Kavicky's flaxen chestnut Haflinger, Moses
Red and Flaxen will only manifest if the horse is homozygous for the allelle of that gene; i.e. Red results only when there are two "e" forms of the Extension gene. A single dominant "E" allelle will overpower it, resulting in a black horse. ("Red" means both Sorrel and Chestnut. These terms have different meanings for different breed registries, and therefore make discussions of color genetics more complicated than necessary. For genetic discussions, it is simpler to stick to "red.")
Flaxen only affects Red. Flaxen on a Black base coat has no effect.
Precisely because both red and flaxen are recessive, flaxen chestnut (red) horses breed true, and breeds have been developed which can be identified in part by their flaxen chestnut coloring. The Haflinger is a breed easily recognized by its lovely flaxen chestnut coloring. Haflingers breed true. A flaxen chestnut Haflinger bred to a flaxen chestnut Haflinger always produces another flaxen chestnut Haflinger. Although there are Belgians draft horses of other colors, flaxen chestnut is the most common color pattern for that breed as well.
By contrast, Palominos, who can look just like a flaxen chestnut, (but are the result of a single Creme gene and Red) when bred together will produce 25% plain red (chestnut, sorrel), 25% Cremello, and 50% Palomino offspring.
Likewise, maintaining an all black breed, such as the Freisian, can also be problematic. Since black is dominant, it easily carries hidden recessives, which can crop up unexpectedly. A test for the Red gene is now available, making it easier for breeders of black horses.
*Genes themselves are not actually dominant or recessive. Alleles are dominant or recessive. For example, the Extension gene codes for the production of eumelanin pigment, causing a horse to be black. A mutation occurred in that gene at some time long ago that coded the gene for the production of phaeomelanin, which produces red pigment.
If a horse carries one copy of the unmutated gene, and a second copy of the mutated gene, the unmutated gene creates enough eumelanin to mask the other copy. Therefore, we say that the unmutated copy, or allele (E) is dominant to the mutated copy, or allele (e). The same is true for all genes: cream, tobiano, overo, dun. But the gene is just a gene. So you can't say that chestnut (Red) is caused by a recessive gene.
Red is caused by the same gene that causes black--it's just caused by carrying two recessive alleles of the Extension gene, whereas black is caused by carrying at least one dominant allele of the Extension gene.
The Pearl dilution is a recessive gene, and therefore will only affect the coat of the carrying horse if:
1) Two inherited copies of the pearl dilution gene are present. Horses inheriting two copies of the Pearl will have a diluted coat and pale skin. For example, red horses carrying two copies of Pearl will have a lightened apricot coat, mane and tail, pale skin, and light brown eye color.
2) The Cream Dilution gene is also present in the Pearl-carrying horse. The combination of the dominant Cream gene and the recessive Pearl dilution gene will produce a pale coat color similar to that of horses that are homozygous for the Cream gene, such as cremello. The skin is pale and the eyes a blue/green color.
Other Pages In the Color Section of this Website:
The Base Colors: Red Flaxen
Major Headings: A Quick Overview of Horse Genetics | Horse Color Genetics Charts 2 | Equine Base Colors | Dominant Horse Color Genes | The Dilution Genes | Recessive Color Genes | Miscellaneous Color Issues
The Single Dominant Genes: Agouti | Appaloosa | Brindle | Dun | Grey | Pangare | Pintos | Rabicano | Roans & Roaning | Silver | Sooty |
The Pinto Patterns: Tobiano | The Overo Complex: Frame | Sabino | Splash | Tovero
The Incomplete Dominant Genes: Champagne | Creme
The Recessive Genes: Red | Flaxen
Colors with multiple genetic bases: Blue | Brown | White | Roan-like Effects
Color genetics are the same for all horses, regardless of breed or ancestry.
Since this is a Mustang website,
I use and prefer pictures of wild, or formerly-wild horses wherever possible.
Disclaimer: I am not a geneticist. The information on these color pages represents the best scientific info I have been able to locate. Theories and knowledge change over time, and it may be you know something I don't - this site is not intended to be "the last word" in colors, just a guide for those wishing to explore the topic.