The Sulphur Springs Mustang (also known as the 'Spanish Sulphur' and the 'Zebra Horse of Utah') is a threatened strain of the Spanish Mustang, which roams in Southwestern Utah.

During the 19th century, a major trading route known as the 'Old Spanish Trail' passed thorough Utah. Over the years, thousands of Spanish horses, mostly of Sorraia ancestry, were led through this route, and some of them managed to escape from captivity, and run to the nearby Needle Mountains where they lived in isolation. Over the course of a hundred years, these Spanish horses developed into the Sulphur Springs Mustangs.

During the first half of the 20th century, it became a common practice in the USA to capture and sell wild Mustang horses. Many Sulphur Springs Mustangs were captured as well, but a small group of these agile horses managed to find a way to an even more isolated region in the Needle Mountains, known as Sulphur Springs. Thanks to their frugal and hardy nature, this small herd of Sulphur Springs Mustangs could live in their isolated sanctuary in the mountains, which the people of that time could not reach. Today, a couple hundred Sulphur Springs Mustangs still roam in that area, and are considered a protected breed.

The overall conformation of Sulphur Springs Mustangs resembles that of the Sorraia (see the 'Sorraia' breed for more info). They come primarily in dun, but can also come in other colors, though they always have a dorsal stripe and bold zebra stripes on their legs, hence their nickname 'Zebra Horses'. Sulphur Springs Mustangs usually stand between 14.1hh and 15.1hh.