Humans have been selectively breeding horses for various colors as far back as horses have been domesticated. With advances in genetic science, we now know even more about the genetics that make these coat colors. From the basic genes that dictate whether a horse is black, bay, or chestnut to the more intricate combination of genes that create a buckskin or a leopard spotted Appaloosa or Knabstrupper, understanding the genetics behind these colors can enhance your appreciation and understanding of these animals down to their DNA. Here’s our guide to the top ten horse colors, along with the genetic mechanisms that create them, plus some interesting bonus shades.

1. Black (Genetic Variants: E/E, E/e)

A black horse's coat color is primarily determined by genetic variants at two key loci: the Extension (E) and Agouti (A) loci. The Extension locus controls the production of black pigment (eumelanin) through the MC1R gene. Horses with at least one dominant E allele (E/E or E/e) produce black pigment.

The Agouti locus, governed by the ASIP gene, controls the distribution of black pigment. Horses with the dominant A allele restrict black to the points (mane, tail, and lower legs), resulting in a bay color. However, if the horse is homozygous recessive at the Agouti locus (a/a), the black pigment is distributed across the entire coat, resulting in a solid black horse. Therefore, a horse with the genetic combination E/E or E/e at the Extension locus and a/a at the Agouti locus will have a black coat. Because Agouti controls black pigment, it has no effect on a horse with a red base coat (e/e).

2. Red/Chestnut/Sorrel (Genetic Variant: e/e)

A chestnut (or sorrel) horse’s coat is a result of the genetic makeup at the Extension (E) locus. Horses with two recessive e alleles at this locus (e/e) cannot produce black pigment and instead produce only red pigment (pheomelanin), giving them their reddish coat color, which can range from light reddish-brown chestnut to a deep liver chestnut.

Agouti does not affect chestnut horses because they do not produce black pigment, which is what that gene restricts. This means that regardless of the horse’s genetic status at the Agouti locus (A/A, A/a, or a/a), the horse will always have a chestnut coat as long as it has two recessive e alleles at the Extension locus and no additional modifiers.

3. Bay aka Agouti (Genetic Variants: A/A, A/a)

Bay horses display a reddish-brown body with black points, including the mane, tail, ear tips, and lower legs. This color pattern is created by the interaction of two genes at the Extension (E) and Agouti (A) loci. Horses with at least one dominant E allele (E/E or E/e) can produce black pigment. However, the Agouti locus controls where that black pigment is placed.

In bay horses, the dominant A allele at the Agouti locus restricts black pigment to the points, allowing the rest of the coat to remain a reddish-brown color. Horses with A/A or A/a at the Agouti locus and E/E or E/e at the Extension locus will have a bay coat. The combination of black pigment production and its restricted placement results in the classic bay color pattern.

4. Buckskin (Genetic Variant: CR/n)

Buckskin horses have a golden or tan body with black mane and tail, similar to bay horses but with a lighter body color. This coat color is the result of a cream gene (CR/n) acting on a bay base coat. The cream gene is a dilution gene that lightens the red pigment in the horse's coat without affecting the black points (mane, tail, and lower legs).

Buckskin horses have the genetic combination of E/E or E/e at the Extension locus, A/A or A/a at the Agouti locus (making them genetically bay), and a single copy of the cream gene (CR/n). The cream gene dilutes the reddish-brown body color to a yellow or gold, leaving the black points untouched. Some buckskins may also show a faint dorsal stripe or darker shading on their shoulders and legs.

5. Palomino (Genetic Variant: CR/n)

Palomino horses have a golden-yellow coat with a white or cream-colored mane and tail. This color is the result of a single cream gene (CR/n) acting on a chestnut base coat (e/e). The cream gene dilutes the red pigment produced by the chestnut coat, lightening it to the characteristic golden shade seen in palominos.

Like buckskins, palominos have one copy of the cream gene, but their base coat is red (chestnut) rather than bay. Palomino coats can range from pale gold to rich, deep gold to chocolate, and their light-colored mane and tail are a hallmark of this color. Horses with two cream genes would be a different color (cremello), but palominos always have just one CR/n cream gene.

6. Perlino (Genetic Variant: CR/CR)

Perlino horses are a light cream color with slightly darker manes and tails. They are the result of two copies of the cream gene (CR/CR) acting on a bay base coat. The double dilution from the cream gene lightens both the red pigment in the body and the black points, creating a pale cream coat with darker, peachy or coffee-colored points.

Perlinos have the genetic combination of E/E or E/e at the Extension locus, A/A or A/a at the Agouti locus (making them genetically bay), and two cream genes (CR/CR). They typically have blue eyes and pink skin due to the cream gene’s strong dilution effect.

7. Cremello (Genetic Variant: CR/CR)

Cremello horses are easily recognizable by their cream-colored coats, blue or green eyes, and pink skin. This unique appearance is the result of having two copies of the cream gene (CR/CR) and a red base coat (e/e). One cream gene dilutes the color of a chestnut base coat to a palomino, but two cream genes (CR/CR) on a red base (e/e) at Extension, creates a double dilution effect resulting in the pale, almost white shade known as cremello.

8. Dun (Genetic Variants: D/D, D/nd1 or D/nd2)

Dun horses are recognized by their sandy yellow, tan, or reddish-brown body color with distinctive "primitive" markings like a dorsal stripe (a dark line running down the spine), leg barring, and shoulder stripes. The dun gene (D) lightens the horse's base coat color while leaving these primitive markings intact.

Dun horses can have a variety of base coats, including black, bay, and chestnut. A red dun, for example, has a chestnut base coat (e/e) diluted by the dun gene, resulting in a lighter red body with a red dorsal stripe and markings. The dun gene can affect any base color and is known for producing horses with an earthy, rugged appearance.

9. Grey (Genetic Variants: G/G, G/n)

Grey horses are born with a solid coat color, often black, bay, or chestnut, but gradually turn white as they age due to the progressive depigmentation caused by the grey gene (G). This gene doesn’t change the horse's underlying coat color but causes the pigment cells to lose color over time, leading to a grey or white appearance.

A horse with two grey alleles (G/G) will always turn grey and do so faster than a horse with only one grey allele (G/n). Grey horses often retain their darker skin and eyes, distinguishing them from horses with white coats like cremellos or perlinos.

10. Leopard Complex Spotting - Appaloosa (Genetic Variants: LP/LP, LP/n)

Appaloosa horses and Knabstrupper warmbloods are famous for their spotted coat patterns, which are controlled by the leopard complex gene (LP). Leopard spotting is an example of an incomplete dominant trait. This means heterozygous horses (LP/n) have spots, while homozygous horses (LP/LP) might have very few or no spots at all in their white patches.

The most common patterns include the blanket (a white patch with dark spots over the horse’s hindquarters) and the full leopard pattern (spots scattered across the entire body). In addition to their unique coat, Appaloosas often have other distinctive traits like mottled skin, striped hooves, and a visible white sclera around the eyes.

Bonus Colors

11. Overo (Genetic Variant: LWO/n)

Overo is a paint pattern characterized by irregular, scattered white markings that do not cross the horse's back. This pattern is controlled by the frame gene (LWO). Horses with one copy of the frame gene (LWO/n) have jagged, scattered white patches, often with dark areas around the face and body.

The frame gene is associated with Lethal White Overo Syndrome, which occurs when a horse inherits two copies of the LWO gene (LWO/LWO). Foals with this genetic combination are born completely white and suffer from a fatal condition that affects their digestive system.

12. Brindle (Genetic Variants: BR1/BR1, BR1/n)

Brindle horses have a rare and striking striping pattern across their body, which can appear as a mix of dark and light stripes. The exact genetic mechanism behind brindle patterns is not fully understood, but it’s thought to result from chimerism (when two different sets of DNA are combined in one animal) or a rare gene interaction that creates the striped appearance.

13. Silver (Genetic Variants: Z/Z, Z/n)

Silver horses have a black base coat diluted by the silver gene (Z), resulting in a dark coat with a white mane that often has a silvery sheen. The gene lightens the mane and tail to a striking white or silver color. The silver gene can act on any base coat color to give many horses a shiny, or silvery, appearance.

Conclusion

Horse coat colors are a fascinating result of genetic interactions that shape each horse's unique appearance. By understanding the genetics behind colors, we gain insight into the complexity of equine biology and the beauty of genetic diversity. Whether it's the golden glow of a palomino or the striking sheen of a silver horse, each color is a testament to the intricate dance of genes that contribute to the spectrum of equine coats. Exploring these genetic variants not only enhances our appreciation for these magnificent creatures but also provides a deeper connection to the science behind their stunning appearances. Whether you're a horse enthusiast, a breeder, or just someone who appreciates their beauty, there is no doubt that the world of horse colors is fascinating.

Want to know more? Check out our in-depth look at the genetics behind horse colors and learn how to understand a horse’s color DNA results.

Glossary

Locus (plural: loci): A specific location on a gene where certain traits, like coat color, are controlled. Think of it as an "address" on the horse's DNA where specific instructions are stored.

Allele: A version of a gene. Horses inherit two alleles for each gene—one from each parent. These alleles work together to determine traits, like coat color. ** Dominant:** An allele that "overrides" the other allele and shows up in the horse’s traits, even if only one copy is present. For example, if a horse has one dominant allele for black pigment, the horse will have black pigment.

Recessive: An allele that only shows up in the horse’s traits if it’s paired with another recessive allele. In other words, both parents must pass down a recessive allele for it to be seen.

Homozygous: When a horse has two identical alleles at a particular locus, either two dominant or two recessive. This can affect traits consistently, like always passing down the same coat color to offspring.

Heterozygous: When a horse has two different alleles at a particular locus, one dominant and one recessive. The dominant allele usually determines the horse's traits, but the horse can still pass on the recessive allele to its offspring.