Dun coats
Bay dun
A bay dun horse has sandy to ochre hair on its trunk and neck, with darker mane, tail and lower legs. A dark dorsal stripe follows the spine, and bars may appear on the legs.
Bay dun: how the color works and is inherited
Dun lightens a bay-based horse by changing pigment distribution within each hair. TBX3 participates in this process. Some areas retain more pigment, producing the darker markings.
One Dun variant copy is enough for dilution. A horse with one Dun copy passes it on with a one-in-two chance; a horse with two copies always passes one on.
Bay dun: origins and the role of breeding
Dun is an ancient way of distributing pigment within a horse’s hair. DNA research shows that Dun and one non-dun variant existed long before domestication. Breeders did not invent the Dun markings. Fjord and Icelandic horses are among the modern breeds that carry this dilution.
Breeders can preserve Dun by choosing horses that carry it. The lightened bay color and dark markings nevertheless existed before modern breeds and planned crossbreeding.
Bay dun: photographs of horses
A bay dun Quarter Horse with dark mane and tail.
Bay dun Fjords, including a head showing the two-tone mane.
A ridden bay dun Carolina Marsh Tacky at a parade.
A bay dun Henson horse grazing.
A bay dun horse’s head and neck with dark mane.
A bay dun pony photographed in the Faroe Islands.
Erik Christensen, Porkeri (Website - Contact) · CC BY-SA 3.0
Photograph credits
Photographs have been resized. Photographs within scientific figures have been separated by cropping. Colors are preserved.
- A bay dun Quarter Horse with dark mane and tail. — Betty Wills (Atsme) · CC BY-SA 4.0
- Bay dun Fjords, including a head showing the two-tone mane. — Me · Public domain
- A ridden bay dun Carolina Marsh Tacky at a parade. — Anthony Surbeck · CC BY 2.0
- A bay dun Henson horse grazing. — Eponimm · CC BY-SA 3.0
- A bay dun horse’s head and neck with dark mane. — Traroth · CC BY-SA 3.0
- A bay dun pony photographed in the Faroe Islands. — Erik Christensen, Porkeri (Website - Contact) · CC BY-SA 3.0
Bay dun: telling similar coats apart
Buckskin can have similarly golden hair but gets its color from Cream. A dark line on the back alone does not establish Dun: look at the other markings and, when needed, the test result.