The Dilution Genes

Agouti, Cream, Dun, Silver Dapple, Champagne, Pearl

Many horse colors are the result of dilution genes acting on the base colors. They all work similarly in that they dilute the main body color, but not always the color of the legs, mane, and tail. Bay is the most basic dilution color, and it is caused by the agouti gene diluting black. The black body hairs are diluted to a shade of brown while the legs, mane, and tail remain black. Like most dilution genes, agouti is dominant, so if a horse carries it, it will be expressed.

Agouti is technically not a seperate gene, but rather a piece of the black gene called an allele. It can occur in four forms: A-agouti (meaning the horse is bay), a-non agouti (meaning the horse remains black), At-brown (a color often confused with dark bay, but genetically different from bay), and A+ wild-type bay (generally a sandy colored shade of bay, but the black on the legs is often restricted just to the joints).


This is Touch Gold, a light bay TB.

This is a red or blood bay.

This is Rambler's Renown, a dark bay Cleveland Bay. Note the lovely golden undertones and dappling. (Owned by IdleHour Stud)

This is Empire Maker, a dark bay TB.

The horse at left is also a bay, but the black on his legs is restricted to just his joints and pasterns. This is called a wild type bay. It is thought to be a primitive coloration as it is often found in old breeds like the Fjord and Przewalski's Horse.

 

Brown is also a dilution that acts on black as I mentioned above. Though it looks similar to dark bay, it is genetically distinct. Brown (or seal brown) horses are characterized by having a black coat with brown hairs on their muzzles, flanks, inner forearms, and inner thighs. Seattle Slew is an excellent example of this color. (Photos by Anne Eberhardt)

 

Cream: Unlike agouti, which only affects the black gene, cream can modify any color it acts in conjunction with, though it is most commonly recognized when combined with chestnut and bay. The cream gene is an incomplete dominant, meaning it is always expressed when it's present, but it acts differently in its heterozygous (1 copy of the gene) and homozygous (2 copies of the gene) states. Simply put, horses with one copy of the cream gene will have a diluted coat; horses with 2 copies will have a doubly diluted coat. Double dilutes always have blue eyes. The cream gene has very little noticeable effect on black hairs in its single form, but it is very obvious in its double form.

 

Palomino: Chestnut + 1 Cream gene
Chestnuts have no black hairs, so the entire coat is diluted. The mane and tail are almost always white.

Cremello: Chestnut + 2 Cream genes
Cremello is basically a very pale palomino color---white markings are still discernable against the pale cream colored coat. Cremellos have blue eyes and light colored skin. (The only true pink skin is under white markings.)


Buckskin: Bay + 1 Cream gene
Because the cream gene doesn't affect black hairs, the dark points remain even after the bay body color has been diluted.

Perlino: Bay + 2 Cream genes
When two cream genes are present, the body color becomes very pale, and the black points are diluted to a red or brown color.


Smoky Black: Black + 1 Cream gene
The cream gene has very little affect on black hairs in its single state, so smoky black is very hard to distinguish from brown or (very sooty) dark bays. Often the best way to tell if the horse carries the cream gene is to have it genetically tested. Some smoky blacks will fade to a dull brownish shade with sun exposure.

Smoky Cream: Black + 2 Cream genes
A smoky cream Akhal Teke. Notice how his points are still a darker shade than the rest of the body.



When sooty is present along with the cream gene, it can do strange things to the horse's coat. Chex Nu Jewel, a palomino Quarter Horse stallion, has most of his sooty coloration concentrated in his mane. (Photo by McBride Quarter Horses.)


Golden Belle is a sooty buckskin. (Bred, owned, and photographed by Red Fox Farm.)

 

Dun: Like the cream gene, the dun gene is also a dilution gene, but it is a complete dominant rather than an incomplete one, meaning heterozygous and homozygous duns look the same. It is often considered a "primitive" color because most very ancient breeds are predominantly or entirely dun, i.e. Przewalskis, Tarpans, etc. Duns are characterized by certain markings known as dun factors. They usually consist of a distinct dorsal (or eel) stripe down the back, leg barring (or zebra stripes), and cobwebbing on the face. As with the cream gene, the dun gene only dilutes the body color, not the points.

Red Dun: Chestnut + Dun
The chestnut color is diluted to a sandy color, but the mane, tail, and points remain chestnut. The dun factors tend to be the same reddish brown color as the points.

Bay Dun: Bay + Dun
The body color is diluted to a sandy color, but the points remain dark. This mustang shows another typical characteristic of duns---the light colored hairs on top of the mane and at the dock of the tail.

Black (or Brown) Dun: Black (or Brown) + Dun
Whether on a brown or black base, this color is often called grulla, grullo, slate dun, or mouse dun. Once again, the points remain dark while the body color is lightened. (This is Quartz of Croila, a lovely Highland Pony stallion I met when we both still lived in Georgia.)

 

Silver Dapple: Silver dapple (also called taffy) is a dilution gene that only affects black pigment, not red (chestnut) pigment. It acts by changing black or brown horses to a chocolately color, and thus bays to a reddish, sometimes dappled color. (This dappling is unrelated to that caused by the grey gene.) While the legs are often only slightly affected by the silver dapple gene, the mane and tail usually change to a pale, flaxen color. Because of this, flaxen chestnuts are easily confused with silver dapple horses (and vice versa). This color is found primarily in Rocky Mountain Horses, other related gaited horses, stock breeds and mustangs, Icelandics, Shetland Ponies, and Miniature Horses. A few draft breeds have also recently been discovered to carry silver, but it's quite rare.


This is silver dapple on black. Note the diluted mane and tail. Some silver dapple blacks fade with sun exposure to a dappled chocolate or even greyish-brown shade. The latter is very common in Shetland Ponies.



This is Smooth As Silk, a Rocky Mountain horse owned by Fair Chance Stables exhibiting the dappled chocolate shade of silver black.


This is April Sunshine, a light silver dapple bay Rocky Mountain Horse owned by Overlook Stables.

This is Amaretto Blu, a darker silver dapple bay Morab. The manes and tails of silver dapple horses often darken as they age, but they generally do retain flaxen tips. (Bred, owned, and photographed by Tamar's Ventures.)


This is a silver dapple buckskin: black + agouti + cream + silver dapple.

This is Choco Dock Jr, a silver dapple sooty buckskin RMH. He is owned by Alloway Creek Farms. (Photo by Jane Gean)

This stunner is the aptly named Chocolate Roan, a roan silver dapple black RMH owned by Volz's Mountain Horses. (Photo by Christi Volz)

This is Classic's Shogun, a roan silver dapple bay RMH. He is also owned by Volz's Mountain Horses.

This little cutie is a bay dun silver dapple: black + agouti + dun + silver dapple. (He's also a tobiano pinto.)


This Icelandic Pony is a black dun silver dapple: black + dun + silver dapple. (Photo by Chantal Jonkergouw)


Champagne: The champagne gene is a simple dominant dilution gene, much like dun. In other words, if a horse carries the champagne gene, he will be champagne in color. Champagne combined with chestnut is called "gold," with bay is "amber," with brown is "sable," and with black is "classic." Sometimes, champagne is combined with the cream gene as well, producing a color known as "ivory." It is known to act in conjunction with other dilution genes (i.e. dun), but those colors have yet to be named. Champagne horses are usually born with bright pink skin that becomes freckled as they age. They are also born with blue eyes that change to a hazel shade as they get older. The champagne gene is found most often in Tennessee Walking Horses, Missouri Foxtrotters, American Saddlebreds, and Quarter Horses. The best resource for more information and pictures of champagne horses is the Champagne Horse Association.

Gold Champagne: Chestnut + Champagne
The chestnut color is diluted to a golden color, similar to palomino. There is a distinguisihable difference because champagnes have hazel eyes and freckled skin. Many champagnes have a metallic or pearly sheen to their coats. (This is Glenknoll's Moregold, an ASB stallion.)

Gold Ivory Champagne: Chestnut + Champagne + Cream
The chestnut color is diluted by the champagne and cream genes to a pale cream color, similar to cremello. There is a distinguisihable difference because champagnes have hazel eyes and freckled skin. Many champagnes have a metallic or pearly sheen to their coats. (This is Chance's Favorite Ivory, a TWH stallion.)

Amber Champagne: Bay + Champagne
The bay color is diluted to a golden color, similar to buckskin, but again is distinguishable because of the hazel eyes and freckled skin. The points also are more brown than black. (This is Doc’s Golden Champagne, an APHA gelding
co-owned by Natalia Tate and Jordan Pierce.)

Amber Ivory Champagne: Bay + Champagne + Cream
The bay color, affected by both the champagne and cream genes, is diluted to a pale cream color similar to perlino, but again is distinguishable because of the hazel eyes and freckled skin. (This is Wind D's Champ Dominator, a TWH stallion ownder by Rockin' B Walkers.)


Sable Champagne: Brown + Champagne
The brown color is diluted to a mousie grey-brown shade with darker points, very similar to classic champagne. (This is California Champagne, a Paint Stallion owned by Carolyn Shephard.)

Sable Ivory Champagne: Brown + Champagne + Cream
The brown color is diluted to a pale golden-brown shade with darker points, very similar to silver bucksin. It is of course distinguishable by the hazel eyes and freckled skin. (This is Kya, a QH owned by Tara Novotnoy.)

Classic Champagne: Black + Champagne
The black color is diluted to a mousie grey-brown shade with darker points. Just like the gold and amber champagnes, classic horses have the telltale hazel eyes and freckled skin. (This is Go Boy’s Champagne Pride, a TWH stallion owned by Laura Kidder.)


Classic Ivory Champagne: Black + Champagne + Cream
The black color is diluted to a pale silvery grey-brown shade with slightly darker points. Just like the gold and amber champagnes, classic horses have the telltale hazel eyes and freckled skin. (This is Topaz Merry Go, a TWH stallion owned by Bill Howes.)

Double Cream Ivory Champagne: Any Base Color + Champagne + Cream + Cream
Champgane combined with cremello, perlino, or smoky cream creates an irridescent, nearly white coat. These horses have very pale skin and very faint freckling.

 

Pearl: The pearl gene (formerly known as the Barlink or apricot gene) is a recently discovered recessive, cream activated dilution. Because it is recessive, one copy of the pearl gene will not affect coat color (if the cream gene is not present). Two copies of the pearl gene act similarly to a double dilute on the coat, creating colors that are akin to those of the champagne gene. The pearl gene combined with one cream gene produces horses that look very like double dilute creams (i.e. cremello, perlino, etc). For more information about this gene and pictures of pearl horses, please visit the New Dilutions website.


RD Chica, a chestnut carrying pearl

Chestnut + Pearl
Chestnut + Pearl + Pearl
Chestnut + Pearl + Cream

Bravio, a bay carrying pearl

Bay + Pearl
Bay + Pearl + Pearl
Bay + Pearl + Cream
Black + Pearl
Black + Pearl + Pearl
Black + Pearl + Cream

 

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