As breeders since 1988, we receive many questions about coat patterns. Here is a very basic genetics lesson for determining if a horse will pass on the pinto gene or not. Yes, the genetics of color coat patterns is the same in miniature horses as any other breed of horse.
First, what is a pinto? Pinto refers to the coat pattern, not the breed of horse. It is a combination of white hair with pink skin below and a base coat color: black, bay, palomino, etc. Miniature horses may be pintos, not Paints. As such, miniatures may be registered with the Pinto Association of America. Paints refer to a breed going back to Quarter Horse and Thoroughbred bloodlines with the pinto coloration.
Pintos may be tobiano or overo. Typically, the tobiano pinto coloration with have 4 white legs, a dark head except for facial markings, dark eyes, and the white crossing the topline of the horse. With an Overo pinto, the white starts on the belly of the horse, they have solid colored legs, irregular markings and commonly have blue eyes.
My experience with the pintos is the Tobiano pattern.
TT - Pinto Homozygous will always produce a pinto, even when bred to a solid. Homozygous simply means that there are a pair of matching genes which control a particular trait. It is possible to test for the homozygous pinto gene through DNA.
The miniature horse above displays obvious "paw prints",
but a homozygous pinto doesn't always show the pattern so obviously. Note fewer prints on this TT homozygous pinto miniature stallion.
nT - Pinto Heterozygous - Tobiano coat pattern present - Produces pinto coloration 50% of the time and solid 50%. This does not mean that 50% of the offspring will be tobiano. Each time the pinto heterozygous produces an offspring, the resulting foal has a 50/50 chance of being a pinto. For example, we had a solid mare which we always bred to heterozygous pinto stallions. She produced 10+ foals and only 2 were pinto.
nn - Homozygous Negative - no pinto coat pattern present - It is not genetically possible to breed two solid colored horses and produce a pinto. No way for a solid to produce a pinto, unless bred to a pinto.
This chart shows
the possibilities of offspring when mating two horses: