Chestnut Based Horses

Chestnut Based Horses

Chestnut comes in many different shades of color, from bright copper chestnut to the dark Liver Chestnut.- Note - Seal Brown is a BLACK based color and not to be confused with Liver Chestnut.

Horses are capable of producing two basic pigments within the hair shafts.

Eumelanin = black pigment
Pheomelanin = red pigment.
The Extension (E) locus controls which of these two pigments the horse is capable of producing. There are two primary known alleles at the E locus: a dominant E and a recessive e.

The recessive e allele allows a horse to produce only Red Pigment or Pheomelanin in the hairs of its coat.

The dominant E allele allows a horse to produce Black Pigment or Eumelanin as well as Red Pigment (Pheomelanin) in the hairs of its coat.

In addition to the Horse's BASE color, it may also
have white patterns, Color Modifiers, and other
unexplained colors/patterns.

If you study the chart to the Left, you'll note that whenever a horse is ee-- recessive chestnut, it doesn't matter what alleles are present at A. Whether A is homozygous, heterozygous, dominant or recessive alleles, the horse remains Chestnut. This is why, when you breed two chestnuts together, you always get some form of chestnut.

For black color to show itself, the horse has to be "genetically black" at the E locus (carry at least one dominant E allele) ... AND the horse must also be recessive aa.

This may help to explain why black color can be so elusive to breed for in horses, and why it can suddenly pop up unexpectedly.

Chestnut Based Horses Color Dilutes & Modifiers

Color Dilutes:

A. Dun Dilutes – Chestnut Dun/ Red Dun

B. Cream Dilutes – Palomino (one cream gene)
Cremello (two cream genes)

C. Silver Dilutes – Does not Show - Called Chestnut but is a silver carrier

D. Champagne Dilutes - Gold Champagne

E. Roan Patterns - Chestnut Roan/ Red/ Strawberry Roan

Color Modifiers

A. Bay – Black Base with a restrictor gene. You will not be able to tell a chestnut horse has the Bay gene as there is no black to be expressed by it.

B. Grey – click here to see Grey colors. - Grey is an ongoing process of depigmentation of the colored hairs. Grey slowly removes the pigment from the base color. Grey is dominant, meaning, the horse must have at least one Grey parent to be Grey and if a horse has Grey it will be shown physically. All Grey horses have a base pigment of either red or black and depending on what other genes are present all Grey horses were another color at birth.

C. Flaxen - Flaxen is a modifier that affects the mane and tail, causing it to become a white to cream color.

D. Sooty/ Smutty - It acts on both red and black based horses by darkening the color or certain areas of the horse. It varies in extent from minimal to extensive and has a many different expressions.
Sooty - can cause dapples, it can cause individual black hairs, it can cause a darker shade along the topline and it can also darken the animal in a uniform manner. Sooty is most concentrated along the top of the horse, like a bucket of ash was poured from head to tail.

E. Mealy/ Pangare - The effects of this modifier are seen along the underside of the horse. In the "soft" parts, or on the muzzle, behind the elbows, in the flanks, on the buttock, above or around the eyes and along the belly. The color of these areas depend on the color of the horse but usually range from white to a light tan.