NWBHC Equinealities, Chestnut Color

Chestnut

Probably the best of all self colors, it is recessive to all dominant colors. Horses whose documented ancestors are mainly of dominant colors may produce chestnut offspring. While the darkest chestnut will occasionally have some small black spots over the rump and along the back, none of the spots are very alrge, nor are they close together. In the opposite extreme, the standard and lighter chestnuts sometimes have a mingling of white hairs insufficient to qualify as a roan. And while the darker self colors, when carefully selected and crossbred, will often produce the same shade, lighter chestnuts can come from the intense colors. The usual breeding of darker chesnuts to chestnut is generally the source of the lighter shades. Some shades of dilute colors also come from chestnuts, but an intense color has never been produced by breeding chestnut to chestnut.

Inside the shaft of hair is a pigment pattern which appears as a cloud-like arrangement of pigment bodies which are fused together. There are generally odd numbers of these pigment bodies, numbering from 3 to 7 in each cloud-like pattern. There is a fine needle of pigment connecting one cloud to the next to stabilize the pattern inside the hair shaft. These "needles" do not add to or detract much from the refraction of light in the pattern. It is the density of the cloud patterns which creates the shades. The more dense the clouds are, the darker the color, and less dense clouds produce lighter shades. (See also sorrel color.)

Liver Chestnut

The darkest of the self colors, the hide of a liver chestnut horse withstands heat, light refraction and "sunburn" rather well. It is not as resistant as the four darker shades of bay. While there is controversy as to whether or not it is a self color, the confusion may be due to the density of the cloud-like patterns. These pigment patterns are triangular- shaped and the deposits are composed of 5 to 7 particles, which are arranged in a light pattern. This allows a very small percentage of light refraction to pass through the hair shaft.

Dark Chestnut

Of equally servicable hide and hair, dark chestnut occurs due to a slight difference in pigment which results in a greater refraction of light. In all chestnut shades, the clusters of pigment deposits are composed of 3 to 5 colors, the lighter shades produces by less intense concentration. The evidence as to why all chestnuts will scald more under heat, sweat, and pressure is due to the fact that the cloud-like patterns do not offer as much protection to the hide.

Standard Chestnut

There is sufficient pigmentation in the hide and hair of the standard chestnut to be equally useful. There is a uniform color throughout the coat, the only light tones occurring in the highlights in the coat. The concentration of the pigment clusters is less dense than the liver and dark chestnut, and it results in a uniform color.

Bright Chestnut

The light refraction appears very bright to the eye and it does not protect the hide as well as the darker shades. The pigment clusters are even lighter in concentration. This is the first of the self colors subject to the caustic effects of sand-scald. Not to be confused with "sunburn," which occurs due to weat of man-made trappings, sand-scald is the result of heat, sun and dryness of hotter and more acid regions.

Dusty Chestnut

The most peculiar shade of chestnut, dusty chestnut has pigmentation in the hide which makes it as durable as standard chestnut. The peculiar quality occurs in the tips of the hair, which are fused together and solid. As a result the pigmentation cannot be distributed to teh full length of the hair shaft. This faint pigmentation in the tips, laid over pigment hairs, gives the dusty appearance. The cloud- like pattern does occur in the section of the hair that is pigmented, and the hide is not weak-pigmented.

Light Chestnut

A controversial color from the standpoint of classification, light chestnut when bred back to darker shades and many of the intense colors often produces darker chestnut offspring. There is argument, supported by the fact that two light chestnuts sometimes produce a dilute skin pigment and a shade of hair lighter than many chestnuts, that it should be classed as a dilute. Such progeny could be classed as a claybank or occasionally a palomino. The lightest concentration of chestnut pigmentation occurs in the light chestnut. In view of the light chestnut, it is questionable whether or not to classify all chestnuts as self colors.

Look for an update on this article with genetic information soon.

Source:

Green, Dr. Ben. The Color of Horses, The Scientific and Authoritative Identification of the Color of the Horse. Northland Publishing. 1974.