of the inheritance of dominant black color has been described and studied in other animals.
The presence of this allele leads to the formation of black color even in genetically bay horses. As a result the carrier of this allele has a black color that cannot be distinguished from ordinary black horses (EE aa or Ee aa). Thus, allele “ED” is epistatic with respect to allele “A.”
A foal with dominant black is similar to bay: brown with darker guard hair rather than the ashy color typical for ordinary black foals. The phenotype of the foal carrying dominant black becomes darker with age.
Diluted Colors
Next we will discuss color modifications determined by dilution mutations. Currently there are several separate dilution genes (for example, Cream, Silver, Champagne, Dun), and each has its own biochemical and molecular mechanism of action. More often it is possible to view color dilution as a weakening of pigmentation, and the molecular mechanisms of the action of some of these genes/mutations are still unclear.
COLORS DETERMINED BY CREAM DILUTION
Buckskin
A buckskin is a bay horse with one Cream Dilution allele (Ccr). Buckskin horses have a sandy yellow color of trunk, neck, and head, while the mane, tail, and lower parts of the legs are black (Photo 17). The nuances of body color are broad—from pale yellow or almost white to dark yellow. The lower part of the legs sometimes appears brown rather than black. The skin is pigmented but can be somewhat lighter than in a bay horse; the eyes are hazel or amber. Dapples are frequently observed.
I distinguish three varieties of the color, depending on the bay base: light buckskin, average buckskin, and dark buckskin. Light buckskin horses are characterized by sandy, sometimes almost white coloring of body. Average buckskin horses have a standard yellow body color, and as a rule, dark buckskins can have a significant amount of dark hair, concentrated on the upper back (countershading) in contrast to the lighter abdomen (Photos 18 & 19). The parts closer to the darker area tend to show dapples.
Newborn buckskin foals are typically light in color, tending to darken after they shed their baby hair. The lower part of the legs can be diluted or black, and with time the black zone tends to extend almost to the knees and elbows.
This color is encountered in many breeds: Lusitanos, Quarter Horses, Miniature Horses, Shetland Ponies, Welsh Ponies, Connemara Ponies, Australian Ponies, and Kinsky horses, for example. Light or dark buckskin color (with visible countershading) is common in the Akhal-Teke breed, and the Byelorussian Harness Horse frequently features very light-colored horses with an almost white trunk. Very rarely is the buckskin color found in Orlov Trotters, and only very recently was it discovered in Thoroughbreds.
Smoky Black and Smoky Seal Brown
In some countries the smoky black color is not considered its own entity and is not recorded in breeding documents, and rarely is referenced in the literature. Visually this color is difficult or even impossible to distinguish from faded black (see p. 11). Smoky black horses can have smoke-colored hair, and in such cases the shade is uniform over the entire body. The main difference between the smoky black and faded black horse is that in a smoky black animal there is almost no difference between the color of the neck and head. The skin and hooves are pigmented, and the eyes can be a walnut color, causing this color to sometimes be called “yellow-eyed black.”
The smoky black color is on a very rare occasion similar to dark bay or seal brown. In such cases a precise determination of color can be accomplished by an analysis of pedigree data and by performing appropriate DNA tests. For example, if one of the parents of a black horse is double cream (cremello or perlino—see p. 20), then the horse in question must be smoky black. It can also help to study the offspring of the particular horse mated with horses of colors not connected to Cream. If a questionable “black” horse mated with a bay or red produces a buckskin or palomino foal, then the horse must be smoky black. Similar logic would apply if this “black” horse produces a double cream dilute (cremello or perlino) foal.
Smoky black foals are born looking similar to regular black—ashy, sometimes with silvery nuances (Photo 20). Also at a young age they frequently have broad darker bands, which run from the spine parallel to the ribs. The eyes are dark blue and the ears are frequently light inside with black edges. Young smoky black horses can for some period of time acquire dark brown shade. Smoky black horses that have a noticeable dark coffee shade are frequently seen in the Akhal-Teke breed, but this color is also encountered in other breeds carrying the Cream Dilution in their gene pool.
Sponenberg (2009) also mentions a very rare color he refers to as smoky seal brown. This color is most commonly encountered in Morgans and Quarter Horses, although in principle it can be encountered in any breed where the Cream Dilution gene is present. Smoky seal brown horses are visually not different from faded black. Their bodies are almost black but with the expressed red nuances around the muzzle and eyes that are characteristic for seal brown color (see p. 12). The legs as a rule are black. So far the only registry using appropriate names for genetically seal brown horses that are also carriers of dilution genes is the International Champagne Horse Registry (www.ichregistry.com). In almost all other registries, such horses are recorded as brown, dark bay, or black.
Palomino
Palominos are horses with chestnut base color, carrying one Cream Dilution allele. They appear bright pale yellow with white mane and tail (Photo 21). The skin is dark gray, although it can be somewhat brighter than the skin in chestnut horses, and the hooves are pigmented. Palomino eyes are typically brown color and only rarely hazel or amber. Eyelashes are yellow or light red.
In palominos the hair has a light red color with the characteristic cream tone, but the determination of shades requires practice. Dark palominos have saturated honey-red color and can be mistaken for chestnuts with flaxen manes and tails. Light palominos are characterized by a sandy colored body, and the mane and tail are practically always white (Photo 22). Sometimes a palomino can be so light that you mistake him for a cremello, but the main difference is the pigmented skin (see p. 20).
There is a special version of light palominos with sooty countershading. Such horses show a significant admixture of dark brown hair concentrated along the spine and extending downward to the sides. Bright, contrasting, yellow dapples and admixture of dark hair in the mane and the tail are frequently present (Photo 23). From a distance, some of these horses appear dirty yellow. This shade is so unique that in Australia it has its own name: lemonsilla. In other places it is common to designate such horses simply as dark palominos. The extremely rare countershading against the light background is expressed so strongly that such horses look practically completely dark brown, and the mane and tail have a significant admixture of brown and dark yellow hair, or they can be almost completely dark brown. This horse can be erroneously labeled “brown,” and a precise color identification is, in such cases, possible only through DNA tests (or less reliably by pedigree analysis). It should be noted that many palomino horses noticeably change color tone according to the season.
Palomino foals are usually born very light cream or almost white-colored, sometimes with pink skin, which becomes darker in the course of time.