Champagne Gene - Coat Colors - Interaction With Other Coat Color Factors

Interaction With Other Coat Color Factors

The presence of other coat color modifying alleles has no effect on whether or not a horse has the champagne trait. However, different traits may interact; they may suppress, enhance, obscure or cancel out various tell-tale clues to the genetic identity of a coat color. Coat colors involving multiple genes often have an unexpected appearance and unique terminology. This type of genetic interaction is called epistasis.

Horses with both the champagne gene and the cream gene are the most common combination. The cream gene is responsible for the palomino, buckskin and cremello coat colors, and is a dose-dependent or incomplete dominant, meaning that a horse with only one copy is visibly different from a horse with two copies of the gene. A single copy of the cream gene dilutes red pigment in the coat to gold or yellow, and has a slight effect on the skin and eye color. The black pigment is lightened little, if at all. Two copies of the cream gene dilute both red and black pigments in the hair to cream or ivory, dilute the skin to a rosy-pink and the eyes to pale blue. The cream gene and champagne gene have an additive or enhancing interaction. Horses with the champagne gene and a single cream gene typically have lighter yellowish or blue eyes and paler, more faintly-freckled skin.

• Gold cream or Ivory champagne refers to an otherwise-chestnut coat affected by the champagne gene and a single copy of the cream gene. The mane, tail, and coat of gold creams are typically ivory and difficult to distinguish from cremello, other than by the skin and eyes.
• Amber cream, similarly, is an otherwise-bay coat affected by the champagne gene and a single copy of the cream gene. The mane and tail of a typical amber cream are a warm yellowish-brown and are often frosted. The legs may also be a light chocolate brown, but need not be. The body coat is a shade of ivory, usually darker than a gold cream. Their points are substantially darker than those of a perlino, and they have champagne skin and eye traits.
• Sable cream is a seal brown coat affected by champagne and a single copy of the cream gene. Sable creams may more closely resemble amber cream or classic cream. Most are several shades darker, with a cooler hue, than amber creams.
• Classic cream is a black coat affected by champagne and a single copy of the cream gene. Classic cream coats should resemble classic champagne shades, being only slightly lightened by the cream gene. Their coats may have a cooler hue.
• Double cream champagne is a coat of any color affected by champagne and both copies of the cream gene. Unlike the coat colors associated with only a single cream gene, double cream champagnes (respectively prefixed with "gold," "amber," etc.) retain no obvious champagne traits. Their skin is clear pink without freckling, and the eyes are pale blue. The terms "cremello champagne", "perlino champagne" and so forth are also acceptable.

Horses with both the champagne gene and the dun gene are also well-recorded. The dun gene is responsible for flat, diluted coat colors and vivid primitive markings. Bay dun is thought to be the wildtype horse coat color. Dun does not affect skin or eye color, but dilutes red pigment to yellow and black pigment to slate gray. Champagne horses with the dun gene will have slightly further-diluted coats compared to non-dun champagnes, and will always exhibit striking primitive markings, such as a dorsal stripe and zebra-like stripes on the legs. Naming schemes are much the same as with champagne-cream combinations. Champagne-dun combinations retain their champagne eye and skin traits. The coats are distinguishable from non-champagne duns in that they are several shades lighter, black pigment is chocolate rather than slate, and they may exhibit a sheen. The coats are distinguishable from non-dun champagnes in the presence of primitive markings and a flatter tone.

• Gold dun refers to an otherwise-chestnut coat affected by both the champagne gene and dun gene. The mane and tail may be ivory or self-colored; the body coat ranges from a warm cream to apricot color with primitive markings a shade darker. The coat is substantially paler and more "yellow" than that of a chestnut dun, and flatter than that of a gold champagne.
• Amber dun refers to an otherwise-bay coat affected by both the champagne gene and dun gene. The mane and tail and primitive markings are warm chocolate brown with a buff tan-colored body. The legs may, or may not, be dark as well.
• Sable dun refers to an otherwise-seal brown coat affected by both the champagne gene and dun gene. The points are chocolate-colored and the coat is darker than the amber dun.
• Classic dun or Classic grulla refers to an otherwise-black coat affected by both the champagne gene and dun gene. The coat possesses more cool slate-gray tones than a classic champagne, while the points are warmer than a grulla.

The silver dapple gene in horses does not affect the eyes, skin, or red pigment. Chestnuts are unaffected, but in bay, seal brown, and black horses, the black pigment is diluted to a chocolate or silver. The mane and tail are most commonly affected. Champagne horses with the silver gene will retain their champagne skin and eye traits, but the black pigment will be further diluted. Silvers vary tremendously in shade and so defining a "typical" example is difficult.

• Amber silver refers to an otherwise-bay coat affected by both the champagne gene and silver gene. The interaction of these two genes - one diluting black to warm chocolate and red to gold, and the other diluting black further to silver - creates an unexpected phenotype. The more closely resembles colors in the red family, mostly deprived of black pigment. The mane and tail may be self-colored, and the coat is buttery and pale.
• Classic silver refers to an otherwise-black coat affected by both the champagne gene and silver gene. The darkest examples resemble classic champagnes with a silvery mane and tail. The palest are a very pale pewter. Some have warm chocolate tones, others do not.

The champagne gene, in combination with some white patterning genes, can also produce unexpected phenotypes. Horses with the leopard gene or Appaloosas exhibit starkly mottled skin around the muzzle, eyes, anus and sheath or udder. Most commonly, the mottling is blocky patches of normal, black skin and unpigmented pink. When a horse has both the leopard gene and the champagne gene, the champagne-associated skin is present only where the skin would be otherwise black.

In combination with gray, champagne produces very unusual coat behavior. Typically, gray horses are born a dark shade of their natural color, and begin to develop gray hairs around the eyes and muzzle. With each shed, the coat becomes lighter and lighter. Many older grays develop the "fleabitten" trait, in which small, interspersed flecks of red occur and often increase in density with age, even as the rest of the coat loses pigment. A few grays will also develop vitiligo in which the skin also progressively loses pigment. When a horse carries both gray and champagne, additional traits occur: Gray-champagnes are born with darker coats than the usual champagne foal, but still exhibiting the expected bright blue eyes and pink skin. The freckling that develops on the skin is also exceptionally dark and dense. Gray-champagnes appear more likely to experience vitiligo. The most unexpected quality of gray-champagnes is the intensity of the fleabitten trait. Flecks of champagne-colored hair are thickly interspersed in the unpigmented white hairs.