Dun coats
Red dun
A red dun horse has peach to reddish-sand hair on its trunk and neck. Its dorsal stripe and any leg bars are red or reddish brown. Those markings are not black because the horse’s base color is chestnut.
Red dun: how the color works and is inherited
Dun, associated with TBX3, lightens a chestnut base. The horse’s hair still contains red pigment, but that pigment is distributed differently within each hair. Less diluted areas form the dorsal stripe and other markings.
One Dun copy is enough on a chestnut-based horse. A red dun foal therefore needs a chestnut base and Dun, which can come from parents with different visible coats.
Red 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.
Red dun brings together the ancient Dun variant and the variants producing a chestnut base. Breeders can select this combination without crossing two particular breeds.
Red dun: photographs of horses
A young red dun Icelandic horse among other horses.
A red dun Fjord with pale mane and tail.
A red dun Quarter Horse foal beside its mother.
A red dun Icelandic horse in the snow.
A red dun in profile with a darker dorsal stripe.
A three-week-old red dun foal resting.
Photograph credits
Photographs have been resized. Photographs within scientific figures have been separated by cropping. Colors are preserved.
- A young red dun Icelandic horse among other horses. — Zelman Menashi · CC BY 2.0
- A red dun Fjord with pale mane and tail. — User:TeunSpaans · Public domain
- A red dun Quarter Horse foal beside its mother. — evelynbelgium · CC BY-SA 2.0
- A red dun Icelandic horse in the snow. — Sela Yair · CC BY-SA 2.0
- A red dun in profile with a darker dorsal stripe. — jumpinghooves · CC BY 2.0
- A three-week-old red dun foal resting. — Bruce McKay · CC BY-SA 2.0
Red dun: telling similar coats apart
A chestnut horse can have a darker line on its back without carrying Dun. In red dun, the lighter coat together with the full set of markings provides the useful clues.