An update of the complete eight-part genetics series that appeared in the January-August 1994 Paint Horse Journals

Paint Horses have an added fascination over that of most other breeds--the spotting patterns that they sport. As a result, they not only have the colors of other breeds, but superimposed over these colors are a variety of spotting patterns.

Knowing about these patterns and their genetic causes can help the breeders and owners of Paint Horses in a number of ways. One way such knowledge is important is that an accurate description of horses is always an asset when equines are the subject of conversation. Accurate understanding of the causes and interactions of the patterns also helps breeders to increase the proportion of spotted horses in their foal crops.

Paint Horse breeding revolves around a few spotting patterns. These patterns are characterized by spots of white on the body. The spots occur in different patterns, and each type of pattern has a separate genetic cause. Manipulating these patterns in a breeding program is straightforward--if the breeder understands the patterns and their genetic control.

Defining the patterns

A good place to start a discussion of Paint genetics is with the basic definitions of the various patterns. With that as a point of departure, it is then possible to focus on each pattern and discuss the genetics of its cause and its appearance on horses.

The term "Paint" lumps together different types of spotting, and at least four major spotting patterns included within the Paint breed. Each pattern can occur separately, or they can occur in all the different possible combinations. Understanding that each of these patterns is separate is the important key to understanding Paint Horse color.

Tobianos and overos

The first major pattern is tobiano. Most people are familiar with tobianos. These are the horses with white legs, dark heads, and spots that are arranged vertically and that tend to cross the topline. The spots usually have a clean, crisp edge.

The second generally accepted type of spotting is overo. Overo, as the word is used today in the United States, actually consists of three entirely separate patterns. Understanding that these patterns are separate is important to understanding how they work in a breeding program.

The history of overo

Knowing the history behind the term "overo" might be helpful in understanding the somewhat confusing situation of having multiple patterns with one name.

Overo is a Spanish word, originally meaning "like an egg." In this case, it refers to speckling or spotting. Long ago in South America, the single term overo was used for all the various spotting patterns in horses: tobiano, overo (all three types) and also the blanket and leopard patterns typical of Appaloosas. In Argentina, the word overo is still used to describe all the different spotting patterns other than tobiano.

In the United States, overo is usually used to mean "Paint, but not tobiano." This has resulted in the lumping together of three different spotting patterns under one name, and the result can be confusion in breeding programs.

Different types of overo

One of these patterns is the "frame overo" pattern. This is the pattern in which the horse generally has a large amount of white on the head, and white spots arranged horizontally on its sides and neck. The feet and legs of this horse are usually dark, although they can have white feet or socks as the non-spotted horse can. Frequently, frame overos have one or two blue eyes.

Another of the overo patterns is "sabino," infrequently called calico overo. This pattern consists of white on the legs and head, and it usually creeps up on the body in the form of belly spots. Calico overos are usually flecked and roaned, although some are crisply spotted. Sometimes sabino horses have blue eyes.

The last pattern is much rarer than the others. It is the "splashed white" pattern. Horses with this pattern have white legs and bellies, as well as a great deal of white on the head. The edges of the white are quite crisp. Many splashed white horses have blue eyes.

These four patterns--tobiano, frame overo, sabino, and splashed white--are the color patterns that distinguish Paints from other horses. In this booklet, each of these patterns will be discussed separately, and then the combinations will be discussed.

Tobiano spotting >