Dun Gene - Breeding and The Dun Gene

Breeding and The Dun Gene

The three primary dun varieties usually occur in proportion to the occurrence of the corresponding base colors in each particular breed. They are created by the following combinations of the dun gene acting upon an underlying base coat color.

• Red (chestnut) base + dun gene = red dun
• Black base + dun gene = blue dun, mouse dun or grullo/grulla
• Bay (black base + agouti gene) + dun gene = classic dun, sometimes called "bay dun" or "zebra dun".

Other variations result from the interplay of additional genes:

• Chestnut + dun + cream gene (single copy) = "dunalino" or "palomino dun"
• Bay + dun + cream gene (single copy) = "dunskin" or "buckskin dun"

A single copy of the cream gene on a black base coat does not significantly lighten black hair, though it may have a subtle effect, and thus a single copy generally has no visible effect on a grullo, either. Conversely, double copies of the cream gene create very light-colored horses (cremello, perlino, and smoky cream). Thus, if a horse with two cream dilution alleles also carries the dun gene, it also will be cream-colored, with primitive markings not visible to any significant degree.

The Fjord horse breed, which is predominantly dun, uses unique Norwegian-based terminology to distinguish between the different shades of dun horses. "Brown dun," or brunnblakk is a zebra dun, rødblakk is a red dun, grå - literally "gray" - is a grullo, buckskin duns are called ulsblakk or white dun, and a dunalino is called a "yellow dun" or gulblakk. A cremello, perlino or smoky cream is called "white" or kvit.