It is very important to understand that there is a major difference between the
appearance of an animal (called its phenotype) and its genetic makeup (called its
genotype). Most commonly encountered discussions of miniature horse coat color are based
on phenotype, as in most cases we can only describe the colors that we see in the horse in
front of us.
OUR EYES TELL US WHAT A HORSE APPEARS TO BE.
HIS PEDIGREE TELLS US WHAT HE OUGHT TO BE.
BUT HIS OFFSPRING TELL US WHAT HE IS...
Since miniature horse colors can be confusing, pedigrees are questionable, if not
non-existent, and evaluating offspring can be a very slow way of determining genetics; we
must try to understand basic genetics to help us predict coat
color.
In horses, a lot of research has been done to explain the various colors but much more
is needed. There are two NEW genetics books that specialize in equine coat colors. Horse
Genetics by Ann T. Bowling and Equine Color Genetics by D. Phillip Sponenberg.
Other good books include Sponenberg's first book and Equine Genetics & Selection
Procedures. An easy way to order these particular books and others is to visit
our recommended book page.
Melanin is the most important pigment of coat color in all mammals. Pigment granules in
the hair, skin, and eyes are made up of either eumelanin (black) or phaeomelanin
(red). Various genes act upon these pigment granules or
"melanocytes" to create the multitude of coat colors in all animals.
The color "bay" seems a good place to start our
Color Guide, since it is probably the "natural" color of the original equine.
The gene responsible for bay characteristics is found at the "Agouti" locus. It
is dominant... that means that when a horse inherits at least one of the "A"
genes it will appear Bay or one of its variations.
The next variable of animal coat color is when the distribution of these pigment
bearing cells is affected. There are sets of genes that influence the distribution of
melanocytes on the body. When these cells are absent, unpigmented white patches appear. We
will now look at spotting factors in horses.
The second great variable in coat color is the shade, intensity and distribution of
the colors present in the pigment bearing cells. There are two primary pigments in the
coats of mammals, RED and BLACK.
Outside of spotting all other aspects of coat colors are due to the action of a series of
genes that affect shading:
- The presence or absence of one or both of these pigments in the hair and skin. For
example: SORREL/CHESTNUT
- The degree of dilution of the pigments present. For example: dun or
GREY
- The pattern of distribution of different colors of pigmented hairs over the body. For
example: roan
