With so many horse coat colors and patterns, once you get into the weeds of color identification and genetics you may never make it out. However, there is one common misconception that deserves some time in the spotlight. When most people think they're looking at a “white” horse, they are usually mistaken. A true white horse is actually extremely rare, even though there are many horses that appear to be white. So…what’s the difference?
The most likely target of a white horse misnomer is a gray horse. Although more rare than bays and chestnuts, they are more common than the other colors we’ll discuss in this article. Gray horses are distinguished by the presence of a gene that causes depigmentation of their coat only. They are born with dark skin, dark eyes, and a dark coat that becomes light as they age. Gray horses maintain their skin and eye color because the gene only affects the pigmentation in their hair (think of humans turning gray as they age.) Unlike most people, gray horses might completely lose their pigmentation in their coats when they’re fairly young; by age 7 or 8 in some cases. There are different expressions of the gray gene that result in different patterns, such as fleabitten grays that appear freckled.
Cremellos, Perlinos, & Smoky Creams:
Often mistaken for albinos, cremellos and perlinos have light blue eyes, pink skin, and light coats. These beauties get their look by a process called cream dilution, which is a result of the presence of the cream gene. This gene causes a lack of pigment cells, called melanocytes, which are responsible for production of melanin. In contrast to albino animals that carry melanocytes that don’t function properly, the cream gene in horses leaves these pigment cells out entirely. There are no known cases of albino horses yet.
There are three base colors that will be affected by cream dilution: black, chestnut, and bay. When they inherit one copy of the cream gene, they are known as single dilutes and their colors are slightly altered to appear as smoky black, palomino, and buckskin accordingly. When they carry two copies and are considered double diluted, we see the “white” look of smoky creams, cremellos, and perlinos. Although there are slight differences between these 3 phenotypes due to the darkness of their base color, they all have light coats, blue eyes, and pale skin.
A true white horse will have pink skin, a white coat, and usually dark eyes. This look appears when horses carry the dominant white gene (W) that can be found on many different alleles. Sometimes, the gene only causes pigmentation loss in about 50% of the horse's body, but in a true white horse, it will cover 100%, which is extremely rare.