By Pat Elder

It can be difficult for the amateur --- and sometimes even for the professional horse breeder --- to distinguish between the two different color patterns in pinto or paint horses. To try to simplify things, I have created the following images and descriptions, based on my years of study and research into equine color genetics. I hope it is helpful in clearing up some of the confusion.

Knowing the parents of a particular horse may help you decide which color pattern it is, because tobiano and each of the three patterns of overo are produced by entirely different genes. An overo cannot produce a tobiano unless bred to one, and under normal circumstances, a tobiano cannot produce an overo. The exception to this is the tovero, a horse that carries both overo and tobiano genes, but these are usually recognizable as such. A few examples will be shown below. In the rare event of an apparent overo out of tobiano parents, a HIDDEN overo gene would have to be the culprit. This is how crop-out overos (overo pintos produced from two apparently non-pinto parents) occur, but they are uncommon. Exactly how this happens is still a mystery to geneticists. Suffice it to say that if a pinto horse has one or both tobiano parents, it is overwhelmingly likely to be a tobiano, too. If neither parent is a tobiano, a paint or pinto can be assumed to be an overo. (See *Note below.)

Now for the descriptions:

Tobiano is the most common color pattern in pinto or paint horses, especially in miniatures. It can best be described as having white markings that usually seem to come from the top of the horse and run down toward his hooves. Notice, I said "usually." You will see that word over and over again in this article, because there are very few hard and fast rules in pinto color genetics, and virtually none in the patterns themselves. Exceptions will always occur, and are often rather frequent.

Tobianos usually have white legs and a solid or "normally" marked head. That is to say, they usually have the face markings (or lack thereof) of a solid colored horse; i.e. a star, strip, blaze, etc. Usually they do not have bald or apron faces.

A common misconception is that if the white markings cross the center of the back, between the withers and the tail, then it is a tobiano, if not, it's an overo. This is simply not true. Many minimally marked tobianos do not have white that crosses the back, and many overos (especially splashed white overos) do. Tobianos frequently have their darker color in specific areas: a predominantly dark head, a "chest shield," a "flank shield," and color around the tail head. Usually, the line between color and white is crisp and well defined. Many have two-tone tails, part white, part colored.

The following drawings represent some of the possible tobiano color patterns, but by no means are intended to represent all of them. Keep in mind that these drawings are in black and white, while tobianos or overos can and do occur in any and all color combinations.

Horse #1 has only a tiny white spot in her mane, but she is nevertheless a tobiano. Horses #6 & 7 both are homozygous tobianos, showing the "paw prints" (small, irregular dark spots within their white areas) that these often display. The tiny dark dots on horse #5 are just that --- dots. Only one of her parents was tobiano, so she cannot be homozygous.

Overo is generally the less common color pattern in horses. There are three distinct types of overo, each produced by a different set of genes. The most common is the frame overo. You will see examples below. And, no, "frame" does not mean a mostly white horse that is "framed" in color only along his topline, chest, and head as some seem to believe. As you will see below, a frame overo can be anything from mostly colored with a tiny belly spot to mostly white. A beautiful pattern, that unfortunately often carries the "lethal white" gene. (See **Note below.)