Dun (D and nd1)

Dun is a gene that adds primitive markings but can also dilute coat color. The Dun gene has three genes:

  • D – Adds primitive markings and dilutes base color.
  • nd1 – Adds primitive markings.
  • nd2 – Non-dun, does not add primitive markings or dilute the base color. Horse is not dun.

Horses with at least one D gene will have a diluted coat and display primitive markings of a dorsal stripe and leg barring. The Andalusian to the left displays this dilution and primitive markings on the liver chestnut base coat.

Dun affects all base colors and adds “Dun” to the end of a color name except for horses with a black base and one “D” gene. These horses are called grullo. Other names may be associated with the dun dilution such as “apricot dun” or “claybank dun”. As of now, these terms are not used in Horse Fable but could be used in the future.



The Andalusian to the right displays the nd1 gene on a light bay base. This has added a dark dorsal stripe and leg barring but has not diluted the base coat. On darker coats, this marking is less noticeable than on lighter coats. For black base horses, the dorsal stripe and leg barring is not visible but the horse will still be noted as “Black Dun” in its color name to indicate the nd1 gene is present.