Pinto is dominant, meaning a pinto horse always has at least one pinto parent and will always show some kind of pinto characteristics, even if it’s not obvious.
The two most common types of pinto are tobiano and overo.
Tobianos almost always have four white hooves. Tobianos tend to have smoother, rounder areas of color and the white will typically cross over the back at some point.
Some horses are homozygous tobiano, meaning they carry two tobiano genes and only produce or sire tobiano foals.
Overos often have jagged white markings on a colored background, and the white usually does not cross over the back. Horses that are homozygous for the gene (meaning they carry two overo genes) always develop Lethal White Syndrome and have a non-functioning colon that results in death within a few days of birth. Responsible breeders don’t breed two overos to one another since the risks are high of producing a Lethal White overo foal that will die.
Another original coat can be creme. The cream gene is what gives us palominos, buckskins, smoky blacks, cremellos, perlinos, and smoky creams. When applied to chestnut, the cream gene produces palomino; when applied to bay, it produces buckskin; and when applied to black, it produces smoky black.
If a horse inherits two cream genes from its parents, it’s called a “double dilute", who are very light-colored horses with blue eyes.
A dilute horse will always have at least one dilute parent, even if neither parent looks like it carries a dilute gene. Because smoky blacks can look like seal brown horses, their owners may be unaware they carry a cream gene until they produce or sire a dilute-colored foal.
Finally I think about appaloosa. Similar to the cream gene, the appaloosa gene affects a horse’s color depending on whether the horse carries one or two appaloosa genes. But the appaloosa gene differs from the cream gene due to the wide spectrum of how it can affect a horse’s coloring. When a horse inherits a single appaloosa gene, the horse’s appaloosa coloring can range from a few white hairs on the body to a loud leopard pattern, and some patterns don’t express themselves until a horse is an adult.
When a horse inherits two appaloosa genes, it’s homozygous for the pattern and will always produce or sire horses with appaloosa characteristics. However, a homozygous appaloosa often will not have spots at all, instead displaying a solid white blanket on the hips or even a nearly solid white body with only a few colored hairs.