The Appaloosa’s colorful ancestry can be traced back to the earliest recorded time, but it is in the American melting pot that the spotted horse established itself as a true breed. The Nez Perce Indians of the inland Northwest deserve much of the credit for the Appaloosa horses we have today. As the only Native Americans known to selectively breed their horses, the Nez Perce desired only the strongest, fastest and most sure-footed of mounts. The influx of white settlers to the Northwest changed the Nez Perce’s destiny and nearly destroyed the legacy of their horse-breeding efforts. War ensued when some of the Nez Perce rebelled against imposed treaties. Over several months and over 1,300 miles, the Appaloosa helped the non-treaty Nez Perce elude the U.S. Cavalry in 1877. At the time of Chief Joseph’s surrender in Montana, the Army confiscated most of their horses, including Appaloosas. The prized characteristics of the distinctive horse then became lost or severely diluted due to indiscriminate breeding.

Claude Thompson, a wheat farmer from Moro, Oregon, realized the importance of preserving the spotted horse breed and in 1938, he established the Appaloosa Horse Club to promote and restore the Appaloosa’s position in the equine world. The Appaloosa began its return from the brink of obscurity. While the Nez Perce never called their spotted horses "Appaloosas," the breed’s name comes from either the Palouse River, which flows through the region of eastern Washington and north Idaho where the horses were known to be plentiful or from the Palouse Tribe, whose main village was situated on the Palouse River. White settlers first described the colorful native mounts as "a Palouse horse," which was soon slurred to "Appalousey." The name "Appaloosa" was officially adopted in 1938. Today, over a half million Appaloosas are registered with the Appaloosa Horse Club.

Although Appaloosas are most commonly recognized by their colorful coat patterns, they also have other distinctive characteristics. The four identifiable characteristics are: coat patterns, mottled skin, white sclera, and striped hooves. The Appaloosa Horse Club recognizes thirteen base coat colors. It is not always easy to predict the color a grown horse will be from the shade it has as a foal. Most foals are born with lighter colored coats than they will have when they shed their baby hair with the exception of gray horses, which are born dark and progressively become lighter. A remarkable aspect of the Appaloosa is the myriad of color and pattern combinations they can exhibit. The seven common terms used to describe Appaloosa coat patterns are blanket, spots, blanket with spots, roan, roan blanket, roan blanket with spots, and solid. Appaloosa patterns are highly variable and there are many which may not fit into specific categories easily.

Mottled or partli-colored skin is also an Appaloosa characteristic. Mottled skin is different from commonly found pink (flesh-colored or non-pigmented) skin in that it normally contains dark areas of pigmented skin within its area. The result is a speckled or blotchy pattern of pigmented and non-pigmented skin.

The sclera is the white area of the eye, which covers the entire eyeball except the cornea - the colored or pigmented portion. The white of the human eye is an example. All horses have sclera but the Appaloosa’s is white and usually more readily visible than other breeds. Readily visible white sclera is a distinctive Appaloosa characteristic provided it is not in combination with a large white face marking, such as a bald face.

Many Appaloosas will have bold and clearly defined vertically light or dark striped hooves. However, vertical stripes also may result from injury to the coronet or found in association with a white marking on the leg. Also, light colored horses tend to have thin stripes in their hooves. As a result, all striped hooves do not necessarily distinguish Appaloosas from non-Appaloosas.