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
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. There are two primary pigments in the coats of mammals, RED and BLACK. All other aspects of coat colors are due to the action of a series of genes that affect shading and distribution of those colors.
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.