A Pinto horse has a coat color that consists of large patches of white and another color. In Britain and Ireland, the term used to describe this pattern is "coloured". The Pinto color pattern existed in prehistoric times, and has been specifically bred by various cultures throughout history. Pinto coloring is popular today in the English-speaking world, especially the United States, where the pattern is considered a color breed and several competing registries have formed to encourage the breeding of pinto horses.
A Pinto may be any breed, but must be of the proper color. There are several different registries with varying requirements. The Pinto Horse Association of America (PtHA) defines pinto horses recorded in their registry as a true breed and accepts solid-colored offspring of registered pinto parents as breeding stock, but has strict requirements for full registration. The most generous allow registration of a horse of any breed or combination of breeds with as little as three square inches of white above the knees or hocks, other than facial markings. Some registries also require horses to meet a certain breed or type standard. A few registries will allow registration of a solid-colored foal if the parents were both colored and accepted by the registry.
There are a number of words used to describe the typical color and spotting patterns of pinto horses. Essentially, a pinto horse is genetically created when an allele for a spotting pattern is present in addition to the genes that create the underlying base coat color. The precise mechanism that creates spotting is not fully understood, but appears to be a form of leucism, or reduced pigmentation in animals.
A Pinto differs from a "Paint" solely by breeding. Horses with Pinto coloring and verifiable pedigrees tracing to Quarter Horses or Thoroughbreds have been named the American Paint Horse and are recorded in a separate registry, the American Paint Horse Association. While a Pinto may be of any breed or combination of breeds, and some Pinto registries may have additional restrictions (some do not register draft horses or mules, for example), a horse that is registered as an American Paint Horse must have registered American Quarter Horse, American Paint Horse, or Thoroughbred bloodlines. Therefore, most Paint horses may be registered as Pintos, but not all Pintos are qualified to be registered as Paints.
Thus, it is always correct to refer to a spotted horse as a Pinto. A spotted horse should only be called a Paint if its ancestry is known or if it displays conformation that is clearly akin to that of an American Quarter Horse. However, "paint" or "painted" was also an archaic term used to describe pinto horses bred by various Plains Indian tribes and thus is occasionally used in this context when describing spotted Mustangs.
Although pinto coloration is rare in the wild, people have always had an eye for animals of unusual colors and a desire to deliberately breed for them. Images from pottery and other art of ancient antiquity show horses with flashy spotted patterns. Images of spotted horses appear in the art of Ancient Egypt, and archaeologists have found evidence of horses with spotted coat patterns on the Russian steppes prior to the rise of the Roman Empire. Later, spotted horses were among those brought to the Americas by the Conquistadors.
By the 17th century in Europe, spotted horses were quite fashionable, though when the fad ended, large numbers of newly-unsellable horses were shipped to the Americas, some for sale, and others simply turned loose to run wild. The color became popular, particularly among Native Americans, and was specifically bred for in the United States, which now has the greatest number of Pinto horses in the world.