Download A Guide to Equine Color Genetics and Coat Color

A Guide to Equine Color Genetics and Coat Color
By: Sue Copeland for Practical Horseman
Confused about horse colors? The puzzle over what to call one shade and what not to call
another has been around as long as the modern horse. And although the debate over certain
colors will likely continue to rage, the information we’ve gathered will help you identify some
sixty common--and not-so-common--hues in horsedom. We’ve also simplified basic
geneticspeak to give you an idea of what pairings can produce these colors—and provided
resources that’ll help you dig deeper into the world of color breeding.
Just to get things started... did you know that gray isn’t considered a color, but rather a pattern of
white hairs? Read on!
The ABCs of Color
Actually, the above subhead should read "The A's & B's of Color." We've distilled the standard
color classifications into two categories for ease of visual identification: horses with black points
(mane, tail, ear rims and lower legs--such as you see on a bay); and those with non-black points
(think chestnut).
Simply put, black and red are the two basic equine color pigments. Your horse's ability to
reproduce these pigments is an inherited trait, with red being recessive (see "Glossary," below) to
black.
Each pigment can be modified by other genes, such as the dilution genes, to provide the rainbow
of colors that modern horses wear. (In fact, you’ll see that dilution can be powerful enough to
water down the black on a genetically black-point horse, shifting him into the non-black-point
category.)
In keeping with this duality theme (and excluding white-pattern coats), you need only the fingers
of two hands (plus two fingers) to count the equine world’s primary colors:
Black-point colors are bay, black, brown, grulla, buckskin and zebra dun.
Non-black-point colors are champagne, chestnut/sorrel, cremello, red dun, palomino and silver
dapple.
As with the human hair labels of blond, brunette and redhead, variations within these primary
categories would take many more than twelve fingers to count. Toss in the white-pattern colors
of gray, paint/pinto, roan and Appaloosa, and identification can render you colorblind!
To help you decipher the myriad of equine coat colors, we've grouped them based on the visual
presence or absence of black points, then added a section for white-pattern colors. We've also
given you a broad example of sire and dam color, in the form of a "sample genetic recipe," that
could produce such offspring. While breeding those-colored parents won't necessarily guarantee
you'll get your chosen color, they'll help you to hedge your bets. (For more information on color
genetics, see "Genetics 101," below.)
Black-Point Colors
All of the following colors can be narrowed down visually by their black manes, tails, legs and
ear rims. (Tip: To avoid confusion, focus on leg color--manes and tails can fade in the sun.)
Bay: Body color ranges from reddish-brown to washed-out yellow, with or without a mix of
darker or lighter hairs; dark eyes.
Sample genetic recipe: Bay X any color.
Sample variations on color:
* Blood bay: a rare dark, blood-red shade (almost purple).
* Cherry bay: medium shade of the very reddish of bays.
* Golden bay: a rare lighter, golden tone, rather than the typical bay.
* Mahogany bay: a bay so dark as to be nearly black.
* Sandy or light bay: a light, washed-out, yellowish shade of red.
* Sooty bay: dark shade of bay produced by the sooty effect (see "Glossary" below).
* Standard bay: reddish-brown medium shade without a mix of darker or lighter hairs.
Black: Has solid black body, legs, mane and tail; dark eyes. Note: Some black horses' coats may
fade in the sun; those that don’t are referred to as "jet" or "raven" black.
Sample genetic recipe: Black X any color; bay X any color (needs a bay parent carrying a
recessive black gene).
Brown: Body is brown or black with lighter shades around the muzzle, eyebrows, quarters, flank
and girth. These lighter areas are often called "mealy" (see "Glossary"). Dark eyes. Note: Brown
is not considered a separate color in some registries, but rather a shade of bay.
Sample genetic recipe: Bay X any color; brown X any color; black X any color.
Sample variations on color:
* Seal brown: a black horse whose hair has a mealy look.
Buckskin: This dilute (see "Glossary") version of bay can range from cream to a yellowish or
orange shade; dark eyes. Although buckskins are often confused with duns, today "buckskin" is a
term generally reserved for tan or yellowish-colored horses that have black points but lack a
dun’s hallmark primitive markings (see "Glossary"). The term "zebra dun" is generally used to
describe buckskin-colored horses with primitive markings.
Sample genetic recipe: Cremello X bay; buckskin X any color; palomino X bay; black X bay
(black parent needs to have a recessive cream gene).
Sample variations on color:
* Dusty buckskin: a dark shade of brownish yellow.
* Golden buckskin: a dark shade of gold.
* Silvery buckskin: the lightest shade of buckskin, so light as to look almost silvery.
* Sooty (or smutty) buckskin: dark shade of buckskin due to a sooty effect (see "Glossary").
* Yellow buckskin: a medium shade of yellow; the "standard" buckskin color.
Grulla: This is a dun dilution of black or seal-brown hair that results in a slate-gray or mouse
color. Look for a dark or black head, black primitive markings and dark eyes.
Sample genetic recipe: Grulla X any color; any dun X black; any dun X bay (if bay parent carries
a recessive black gene).
Zebra dun: Horses are similar in body color to buckskin, but with primitive markings. They tend
to be more of a tan shade than the lighter, clearer yellows of most buckskin horses. These are the
most common group of linebacked duns (see "Glossary").
Sample genetic recipe: Zebra dun X any color.
Sample variations on color:
* Coyote dun: black shading over the withers, back and hips, resembling a coyote’s coat; hence
the name.
* Dusty dun: a rare beige body color that’s nearly grulla but lacks that color’s black or dark head.
* Golden dun: a deeper yellow shade.
* Peanut-butter dun: tan body color in a peanut-butter hue.
* Silvery dun: the palest shade of zebra dun.
Non-Black-Point Colors
Just as you can identify certain base colors via the existence of points, you can visually segregate
the following by their lack of black points.
Champagne: This is a recent term for a dilution gene that affects hair and skin pigment. It causes
red hair to go gold and black hair to become chocolate-colored. So while your horse may
genetically carry the black factor, the champagne gene turns it to brown! (To help you visualize
this effect, picture a chocolate Labrador Retriever versus a black Lab.) As a point of
identification, keep in mind that the champagne gene always results in lightened skin that lacks
black, and in amber-colored eyes (which can darken almost to brown with age).
Sample genetic recipe: Champagne or any champagne variation color X any color.
Sample variations on color:
* Gold champagne (genetically chestnut): golden-yellow body and legs; red/gold or white mane
and tail. For years, these were called--and registered as--light-skinned palominos. Particularly
light-colored horses in this shade can resemble cremellos, but the amber eyes tell the true story.
* Amber champagne (genetically bay): gold body; chocolate mane, tail and legs.
* Champagne (genetically black): khaki-colored body that can have almost greenish highlights;
mane, tail and legs are chocolate. A strain in the Tennessee Walking Horse breed is famous for
this color.
Chestnut/sorrel (see "Sorrel Versus Chestnut," below): Reddish or copper-reddish body and legs
are representative of the red factor. Mane and tail can be the same color, flaxen or almost black;
dark eyes. In North America, chestnuts/sorrels are generally named by body shade only, ignoring
mane and tail color. The exception is “flaxen chestnuts.”
Sample genetic recipe: Any color X any color (except cream colors).
Sample variations on color:
* Dark (or liver) chestnut: a liver- or chocolate-brown body, mane, tail and legs. Shades can vary
within this subgroup and are sometimes referred to as "dark liver chestnut" and "light liver
chestnut."
* Flaxen chestnut: a chestnut body with a flaxen mane and tail.
* Light chestnut: also called "sandy chestnut"--a sand-colored body, mane, tail and legs.
* Red chestnut: copper-penny-colored or redder body, mane, tail and legs.
Cream or cremello: This double dilution of chestnut/sorrel results in a color so light as to be
almost white. In many cases the coat is described as ivory; mane and tail are white or nearly so;
skin is pale pink; eyes are always blue.
Sample genetic recipe: Palomino X palomino; palomino X buckskin; buckskin X buckskin; black
X palomino; black X buckskin; black X black (in each case, black parents must have a hidden
cream gene).
Sample variations on color:
* Perlino: same as cremello, except that small amounts of color (cream or coffee-colored) are
retained in the mane, tail and lower leg. (Perlino is a double dilution of bay.)
* Smoky cream or smoky perlino: same as perlino, except that even more pigment is retained in
mane, tail, lower legs and (in many cases) on the body.
Red dun: A dominant dilution gene results in tan to reddish-brown to yellow-colored horses that
could be confused with chestnuts except for the presence of primitive markings (most commonly
a dorsal stripe, or "lineback," hence the general term "lineback duns") and dark points. However,
they lack the black points of a buckskin, grulla or zebra dun--a key point of differentiation.
Mane, tail and legs can be darker than the body color; dark eyes.
Sample genetic recipe: Any color dun X any dun color; any dun X any color.
Sample shade variations on body color:
* Apricot dun: a pale peach-skin or apricot-skin hue.
* Claybank dun: a pale shade ranging from pale straw to yellow clay, characterized by a yellow
cast to the hair; mane and tail are mostly cream or white.
* Sooty red dun: red dun with sooty effect.
Palomino: This color is actually the result of chestnut with a cream dilution factor. Look for a
rich gold to clear-yellow body; manes and tails are generally white or pale; dark eyes.
Sample genetic recipe: Cremello X chestnut (will always produce palominos); cremello X any
color; palomino X chestnut (you’ll get only chestnut or palomino); palomino X any color;
buckskin X any color; black X any color (if black parent has a hidden cream gene).
Sample variations on color:
1. Golden palomino: a body the color of a newly minted gold coin, with a white mane and
tail.Isabelo: the palest palomino shade or dark cream with amber eyes.
2. Sooty (or smutty) palomino: black shading mixed with yellow body hairs; can be quite dark
and difficult to distinguish from a chestnut.
Silver dapple: A dominant gene acts on black pigments (such as points) by lightening them. It
leaves red body pigment unchanged but does lighten manes/tails in red horses. Now known
simply as the "silver gene," as only a minority of horses actually show dapples. Uncommon in
North America, except in pony breeds (think chocolate-colored Shetland with a flaxen mane and
tail) and such gaited breeds as the Rocky Mountain Horse.
Sample genetic recipe: Silver dapple X any color.
Sample variations on color:
* Silver-dapple bay: body red; mane and tail flaxen or mixed; legs light; eyes dark.
* Silver-dapple black: body chocolate-silver dapple; mane and tail flaxen or white; legs
chocolate brown; eyes dark.
Patterns of White
Even though you may think of gray as a horse color, it’s actually considered to be a pattern of
white hairs. Pinto/paint, roan, and Appaloosa are considered to be patterns characterized by
white patches. Here’s how it breaks down.
Appaloosa (or spotted horses): There are lots of leopard-patterned horse breeds in the world, but
Appaloosas are the best known, especially here in North America. The leopard pattern is a
dominant gene that produces coat patterns characterized by dark or white spots, blankets and
"varnish" (see below). Also characteristic of this factor are white sclera visible around the eyes,
mottled skin pigment on the face and/or genitals and striped hooves. A sparse mane and tail can
be typical of some Appaloosas.
Sample genetic recipe: Appaloosa X Appaloosa; Appaloosa X any color.
Sample variations on color:
* Blanket: a dark body with a blanket of white hair over the loins and hips, which may or may
not contain darker spots; mane, tail and legs are dark; eyes are dark.
* Few-spot leopard: white body and legs with a few dark spots scattered throughout; white mane
and tail; dark eyes.
* Frost: roaning-type white spread over the croup and hips; dark eyes.
* Leopard: white body and legs with numerous dark spots; mane and tail mixed; dark eyes.
* Snowflake: white patches up to nearly 3 inches across, scattered over a darker base color.
* Varnish roan: not actually a roan, but rather a manifestation of the leopard complex with a
mixture of white and dark hairs. Bony areas (such as the face, withers, hip and stifle) are darker
than the rest of the body; the exact opposite of the "frosty roan".
Gray: This is a dominant pattern caused by individual white hairs. Such horses are normally born
colored, then progressively acquire white hairs as they age; the body, mane, tail and legs are
gray; eyes are dark. The speed with which graying occurs varies from horse to horse and from
breed to breed. All gray horses eventually turn white or flea-bitten (see below). Some horses'
manes hold color longer than others, but eventually all turn white if the horse lives long enough.
Sample genetic recipe: Any gray X any color.
Sample variations on coat pattern:
1. Dapple gray: dark dappling that can be seen on some young gray horses before they "white
out."
2. Flea-bitten gray: small flecks of color (generally red or black) remain in the coat.
3. Iron gray: gray that lacks dapples.
4. Porcelain gray: older gray horses that are white with pigmented skin.
5. Rose gray: pinkish-gray body color; dark eyes. Not a permanent color, but rather a descriptive
term for a stage of gray through which a bay- or chestnut-hued young horse may go through as
he gets progressively grayer.
Pinto/Paint: Their coats are characterized by irregular, asymmetric patterns of white spotting.
Any number of background colors can exist; mane, tail and legs vary depending on genetic coat
pattern (see below); eyes can be dark or blue.
Sample genetic recipe: Any Paint/pinto X any color.
Sample variations on color:
* Overo: may be predominantly white or dark, generally characterized by dark feet and legs,
with a head marked extensively with white. (Extensive white on an overo head has been linked
to deafness.) Legs may have markings similar to those on solid-colored horses. White spots
generally occur on the body's and neck's middle or sides and only rarely cross the topline
between withers and tail. They tend to be irregular and are described as scattered or "splashy."
Mane and tail are usually one color; eyes may be dark or blue. (Caveat: Breeding overo to overo
can result in a lethal genetic defect, called "Lethal White Syndrome"--see "Glossary.")
* Sabino: an overo pattern that usually involves extensive white on the legs and face. Body spots
are generally on the belly and appear as roan, speckled or (rarely) white patches with clean
edges. Most sabinos are roaned or flecked. Mane and tail are colored or mixed white; eyes are
dark or blue. Minimally marked sabinos lack body spots and have only white leg markings (such
as "high white"--that which reaches to or extends over hocks and knees) and extensive facial
white (such as that which dips under the chin). Such horses aren't classified as spotted but can
produce spotted offspring.
* Tobiano: generally has a dark color covering one or both flanks, with all four legs usually
white below the hocks and knees; mane and tail are often white and dark. Spots tend to be
regular and distinct as ovals or round patterns that extend down the neck and chest and usually
cross the back. Head is usually dark, featuring markings like those of a solid-colored horse (star,
blaze, etc.); eyes are usually dark. Note: Homozygous (see "Glossary") tobianos generally throw
100 percent patterned coat.
* Tovero: a spotted blend of overo and tobiano characteristics.
Roan: A dominant genetic effect results in the intermingling of white hairs with the base-coat
color throughout a horse’s body, but not on the points. True roans are said to be born roan or to
shed out to that color when they lose their foal coats, rather than slowly progressing to it as with
grays.
Sample genetic recipe: Any roan X any color.
Sample variations on color:
* Blue roan (roan over black): white hairs intermingled with black ones; dark eyes.
* Frosty roan: a distinctive and unusual roaning pattern characterized by an uneven mixture of
white hairs (like a frost) mostly over the bony parts, such as the hips, down the spine and over
the shoulders; dark eyes.
* Red roan (roan over bay): white hairs intermingled with bay ones; dark eyes.
So there you have it. A rainbow of equine colors -- ones you can now identify.
For assistance with this article, the editors thank D. Phillip Sponenberg, DVM, PhD, Professor of
Pathology and Genetics at Virginia-Maryland Regional College of Veterinary Medicine at
Virginia Tech in Blacksburg; and Ann T. Bowling, PhD, of the University of California
Veterinary Genetics Laboratory, Davis, California.
Glossary
Allele: Either of a pair of genes located at the same position on both members of a pair of
chromosomes, conveying characteristics that are inherited. (See "Heterozygous" and
"Homozygous.")
Base colors: Referred to as the building blocks of all equine color, these are black and red
(chestnut/sorrel). They form the base from which all other colors can be built via genetic
modifications.
Bend Or or Bend’Or Spots: Random dark spots on a chestnut/sorrel background, ranging in size
from small to large, and generally dark red, brown or black in color. Can occur on other colored
horses, but less commonly. Named after a Thoroughbred horse.
Blood marks: Large, distinct patches of color--usually red, hence the name--that can develop on
gray horses as they age.
Dappling: Roundish-shaped clusters of lighter pigment surrounded by dark borders. Generally
considered a reflection of good health. Most likely reflect blood-flow patterns in horse's skin;
also could indicate slight variations in hair texture and growth patterns, which make the dapples
stand out.
Dilution: Different dilution genes literally "tone down" the intensity of basic body colors. For
instance, a black affected by dilution becomes grulla; bay becomes buckskin; chestnut becomes
palomino.
Dominant gene: A gene that can mask another gene, so its presence is revealed in every
generation. (Compare to "recessive gene.")
Heterozygous: A pair of alleles that aren’t alike on a single chromosome, hence not always
breeding true to type for the color involved.
Homozygous: A pair of alleles that are identical on a single chromosome, hence breeding true to
type for the color involved.
Lethal White Syndrome: A fatal condition that can occur when overo is bred to overo, producing
a homozygous overo foal. Such foals are born healthy and vigorous, with solid white bodies and
blue eyes. Not immediately apparent is the fact that they lack crucial nerves in the intestinal tract,
resulting in a constriction through which material can’t pass. They generally die within three
days. If you're looking for color, breed your overo to a solid horse. You'll have a 50-50 shot at
netting a spotted foal--the same odds you'd have from breeding overo to overo, without the risk.
Lineback (also called "dorsal stripe"): A so-called "primitive mark" (see below) that's darker than
the base color, resulting in a stripe down the horse's back. Generally associated with light colors,
such as duns.
Mealy: A genetic modification that causes pale red or yellowish areas on the lower belly, flanks,
behind the elbows, inside the legs, on the muzzle and over the eyes. An example of the mealy
effect is that of an essentially black horse with a brown muzzle and other mealy markings (often
referred to as "mealy-mouthed"); such a horse would be classified as seal brown. This effect can
also apply to chestnuts in the form of multiple shades of red on the body.
Pigment: Color.
Piebald: An older English term used to describe any black-and-white-colored horse.
Primitive markings: Markings, darker than the base color, including dorsal stripes (lineback), a
stripe over the withers (cross, or withers strip), bars on the hocks and/or above the knees (zebra
or tiger stripes), and concentric rings on the forehead (cobwebbing or spiderwebbing). Most
common in dun-colored horses, but can occur on darker colors, such as bay and chestnut. While
they do occur in primitive breeds, these markings also occur in many highly developed ones.
Rabicano: Coloration similar to roan, except that white hairs are concentrated in the flanks; can
be speckled in appearance. The tail base will also have white hairs; this is a hallmark of the
rabicano. Also known as "skunk tail" or "white ticking."
Recessive gene: A gene that can be masked by another, only to be revealed in future generations.
(Compare to "dominant gene.")
Skewbald: An older English term used to describe white spotting on any color other than black
(see "Piebald," above).
Sooty: Also known as "smutty." A genetic modification in which dark shading occurs along the
back, shoulder and croup, resulting in a horse that’s dark on top and light underneath, as though
he’s been covered in soot.
Sorrel Versus Chestnut
So...is your chestnut really a sorrel? Or is that sorrel really a chestnut? It depends--and it’s
subjective.
Different breeds use the two terms to describe different genetic variations or shades of color. For
instance, draft-horse breeders often reserve the term "sorrel" for chestnut horses with the mealy
effect (see "Glossary") superimposed. Other breeds, notably the American Quarter Horse, apply
the term based on body shade alone: To them, "sorrel" refers to red or lighter chestnut shades,
with or without the mealy effect.
A third approach, though rare, is to use the term "sorrel" to describe a light chestnut with a flaxen
mane and tail. The common link to the term "sorrel" seems to be its reference to lighter-colored
chestnut horses--despite the fact that draft-horse fanciers and Quarter Horse aficionados each use
different logic to arrive at that description.
Bottom line? Unless you're into Quarter Horses or draft breeds, "chestnut" may be the term of
choice, at least in a generic sense. Check with your breed registry, if applicable. They can tell
you what colors they do and don't recognize, so you can most accurately describe your horse's
color for registration purposes.
Paint? Pinto? What’s Right?
When is a pinto not a paint? When you're referring to breed associations rather than color
patterns. Even then, a Paint can sometimes be a Pinto, and vice versa.
Confused? Here's how it works.
The terms "paint" and "pinto" generally mean the presence of asymmetric white spotting patterns
on the horse's coat. In this generic sense, they're often used interchangeably. Confusion over
proper usage has lingered because in years past the term "paint" was used to describe a piebald
horse (see "Glossary"). "Pinto" was used to describe a piebald or a skewbald (see "Glossary"
again). No wonder we were mixed up!
The trend has been to drop those dated English color descriptions in favor of genetically
distinctive coat patterns, such as overo and tobiano.
However, confusion still arises when "paint" and "pinto" are used to designate breed names. The
American Paint Horse Association and the Pinto Horse Association of America add
documentation of pedigree qualifications to genetic color patterns. The difference in eligibility
between the two registries has to do with bloodlines:
Paint Horses (those registered by the APHA) are of Western stock type and are limited to
equines of documented and registered Paint, Quarter Horse or Thoroughbred breeding. The
PtHA registers similar stock-type horses and also allows for registration of Miniature Horses,
ponies and horses derived from other approved breed crosses, such as Arabian, Morgan,
Saddlebred, Tennessee Walking Horse, plus some warmblood registries. Most Paint Horses can
be double-registered as Stock or Hunter-type Pintos. (For more information, contact the APHA
at (817) 834-2742 or www.apha.com; or the PtHA at (405) 491-0111 or www.pinto.org.)
Still confused? Here’s a simple rule of thumb: When the word "paint" or "pinto" is being used in
a generic, descriptive sense, it doesn't need capitalizing. (Example: "George Morris was observed
standing by an unidentified pinto at the in-gate.") In such a case, either term is OK. However,
when you're referring to a horse that's registered as a Paint Horse (another clue--the APHA
prefers that nomenclature to help thwart confusion) or a Pinto, treat the term as a proper noun.
(Example: "A Paint Horse called Impressive Spot won the Hunter Classic at last Saturday's
Happy Meadows Horse Show.")