Think of
all the horse colors that you know... and there are perhaps
dozens that you may not know of. From red roans to tobiano buckskins,
every color seen in equines is made up of only two pigments:
red and black, or the absence of those pigments (white).
These two pigments, together with modifying genes or areas that
lack pigment (white), make up all the colors.
The red pigment is called phaeomelanin (fee-o-mel-a-nin)
and the black pigment is eumelanin (you-mel-a-nin). They
are both forms of melanin, which is a skin and hair pigment.
Melanin is made by melanocytes, special cells in the skin. There
are two types of melanocytes; those that have skin pigment,
and those that don't. Where the melanocytes have no skin pigment,
the hair will be white-- an example is a blaze. The melanocytes
that do make skin pigment will create different coat colors.
Most horses have both types of melanocytes. Sometimes they can
switch-- dark hairs can become white in instances, such as injury.
There are four main colors that are called the base
colors. They are the most common, and make up the base for all
other colors. They are black, chestnut, bay, and
brown.
How then, if all horses are red and/or black, do we get colors
such as palomino? Well, there are genes that dilute the main
pigments to lighter colors. There are four main diluting genes--
the cream dilution, dun dilution, champagne
dilution, and the silver dilution.
Other ways that the colors are changed are by the Agouti gene--
a gene that restricts black to the points (legs, mane, tail,
eartips). Bay-based horses (buckskin, bay silver, bay dun, etc.)
have this gene.
There are other genes, too, which affect the horse's color.
The flaxen (F) creates a light mane and tail, and lighter body
in horses with the e (chestnut) gene. The gray gene (G) eventually
turns the horse gray, regardless of other genes. It is much
like the way human hairs go gray; they get lighter with age,
but in horses the graying starts at a very young age. The pangaré
(P) makes the horse's muzzle, belly, and flanks lighter.
Pintos, which are horses with large patches of pigmentless hair,
are caused by four different genes or a combination of them:
the To (tobiano), Sb (sabino), Fr (Frame overo) and Spl (splashed
white) genes.
Many solid colored horses carry these genes, but they are only
minimally expressed-- such as in white facial or leg markings.
This is how solid breeds, such as the Quarter Horse and Thoroughbred,
sometimes create a pinto-colored or an all-white horse.
How did I classify the colors? Well, I've placed the Base colors
into one section, then the dilutes (colors with a diluting gene),
then Patterns (roan, gray, and the like) Broken Colors (pintos),
and Spotted (spotting patterns). In the "Other" section, you'll
find white, and brindle, as well as some info on Pintoloosa.
Since it fits either the Broken or the Pattern category, I just
decided to put it in 'other'.
The markings section, I think, is the most fun. It not only
discusses the regular facial and leg markings, it also has pictures
and information about marbling, cobwebbing, ghost markings,
bloodmarks, watermarks, pangaré and flaxen effects, mismarks,
acquired spots, ermines, Bend or, flash marks, countershading,
dappling and reverse dappling, and primitive markings and characteristics.
This section actually includes a lot more than just markings!
Have fun with the site, and remember, I'm always looking for
photographs of unusual or rare colors or markings!
