The dun horse with its vivid primitive markings set against a muted coat is one of the most visually striking equines around. However, where colors like palomino have been created by changes to DNA in various pigment-associated genes, dun is the original ancestral color of the domestic horse.
In this post, we study the genetics underlying the dun coat color, and discuss the various shades and patterns of dun. We also explain primitive markings, consider which breeds have dun, and its prevalence in those breeds.
Color Features of Dun Horses
Base Color
Duns can be any of the 3 base colors – bay, black, or chestnut. They can also be one or more of the other dilutions (cream, champagne, silver, pearl, mushroom).
Genetics
The dun coat color results from the ancestral version of DNA coding (D) at the TBX3 gene, which produces primitive markings and a muted coat. Duns may have 1 or 2 copies of this DNA.
Primitive Markings
All duns have primitive markings. These are the dark stripes and patterns on their coat (dorsal stripe, leg barring / mottling, ear tips, face mask, frosting).
Coat Shade Range
Duns can be any coat shade but the distinguishing feature is its muted appearance. A bay dun for example is often a light tan or beige color depending on the underlying shade of bay. A black dun, or grulla, is a slate grey. Red or chestnut duns are more apricot than red in appearance.
Mane and Tail Color
A dun’s mane and tail are the regular color associated with their base coat or color genetics (bay and black-based duns have a black mane and tail, red duns have a red mane and tail, palomino duns have a cream or white mane and tail… and so on).
Skin Pigmentation
The genetics that create dun coloration do not alter skin color. Therefore, duns will always have the skin color associated with their underlying color genetics – dark in base-coated duns, pink in double cream (perlino, cremello, smoky cream) duns etc. They also have pink skin under white markings.
Eyes
Again, a dun’s eyes typically align with their skin color / color genetics. Dark-skinned duns (bay, black, chestnut etc) have dark eyes. Those with a coat dilution of some type will have the eye color associated with that dilution – double cream duns for instance have blue eyes. If a coat pattern like frame overo or splashed white is present, they may have parti-colored or wall eyes.
Points (Legs, Ears)
The lower legs are dark in bay and black-based duns, and red or self-colored in chestnut-based duns. If another dilution is present, it will dilute the legs to the color associated with that dilution.
The ears are the same color as the body but often have a darker undiluted “cap” covering the upper half or top of the ear. This marking is called an “ear tip” and is one of the primitive markings associated with dun.
White Markings
Duns can have standard white markings on the legs and face. If they carry a coat pattern gene, (frame overo, tobiano, or PATN/leopard complex (Lp)) they may display the white markings associated with those genes.
The Universal Appeal Of The Dun
Despite being the horse’s ancestral color, duns are not particularly common today. This is largely due to selective breeding by humans who initially preferred the brightly colored non-duns. Over time, their numbers overtook those of duns, and duns are now vastly out-numbered in the general equine population! This “uncommonness”, along with their spectacular markings, contributes to their appeal.
Genetics Of The Dun Horse Color
As mentioned, the early ancestors of the domestic horse were always dun (and bay). Non-duns didn’t appear until after some genetic changes happened in the DNA coding at a gene called the TBX3 gene. These changes, designated nd1 and nd2, progressively brightened up the coat and removed the primitive markings to create the clear coated, bright, shiny horses we have today.
Some horses though still have at least one copy of that original, unaltered DNA (D) at their TBX3 gene. This DNA produces the characteristic primitive markings and muted coat tones typical of primitive horses and our modern dun horse.
- Genetically, a dun horse may be DD, Dnd1, or Dnd2.
- There is no visible difference between duns with one copy of D (D_) and those with two copies (DD).
- Non-duns are always nd1nd1, nd1nd2, or nd2nd2 (“nd” of course stands for “non-dun”).
Dun Horse Color Variations
Dun modifies all coat colors to produce the characteristic “faded” or washed out version of the original color. This trait is caused by one-sided pigment distribution in the hair shaft, a noted dun attribute.
- A bay horse with dun is a muted light to medium tan color with dark points and black and bay primitive markings depending on where they occur on the body
- A black horse with dun is generally called a grulla (grew’yah) and is a slate grey to dove grey color with black points and primitive markings
- A chestnut horse with dun, or red dun, is an apricot or pale red with red points and primitive markings.
Dun Combined With Other Coat Color Modifying Genes
Dun can also occur in combination with other coat color modifying genes to produce a range of interesting colors.
- Dunalino (palomino dun): Palomino with dun.
- Dunskin (buckskin dun): Buckskin with dun.
- Smoky Grulla: Smoky black with dun.
- Cremello Dun / Perlino Dun / Smoky Cream Grulla: double cream with dun on chestnut, bay, and black respectively.
- Champagne Dun: Champagne with dun – may be Amber Dun, Classic Dun, or Gold Dun depending on base color.
- Silver Dun: Silver with dun.
- Broken-colored Dun: Dun with patterns like tobiano, frame overo, PATN/leopard complex (Lp), or roan.
Dun Primitive Markings
Primitive markings are a well-known and much-loved feature of dun horses. While we don’t know “how” they’re created, they likely evolved to help camouflage the animal and are usually the undiluted color of the underlying coat. A bay dun for example usually has a bay colored dorsal stripe and will have a combination of bay and black leg barring depending on their location.
Common primitive markings found on most duns include:
- Dorsal stripe: a clearly defined stripe running along the spine of the horse from the withers down into the tail. Some duns also have dorsal barbs extending out from the sides of the dorsal stripe.
- Leg barring: horizontal stripes around the forearm and hocks, often extending down to the lower legs.
- Mottling: a lacy pattern on the forearms and hocks, either in combination with or sitting just above the leg barring. May also extend to the elbows and upper arm.
- Ear tips and edging: a solid cap of dark hair covering the upper half of the ear (ear tip) and a dark rim (edging) around the front edge of the ear.
- Cobwebbing: fine lines radiating out from the centre of the forehead.
- Face mask: dark hair on the face, usually in an inverted ‘V’ shape starting between the eyes and covering the bottom half of the face and muzzle.
- Shoulder or wither patch: a patch of dark hair across the withers.
- Neck shadow: a patch of dark hair in the hollow of the neck.
- Frosting: coat colored guard hairs along the top of the mane and tail.
NB: Not all duns have all these markings; many only have 4 or 5 including the dorsal stripe (found on all duns) and leg barring.
Common Dun Breeds
Dun is a color, not a breed. However, some breeds are always dun in color, and a few are predominantly dun.
Dun Breeds
These breeds are always dun. Except for the Henson Horse, they share many physical similarities with prehistoric horses.
- Norwegian Fjord
- Przewalski’s Horse
- Konik
- Riwoche horse (always bay dun)
- Henson Horse
Predominantly Dun Breeds
Dun is very predominant in the following breeds but unlike the above breeds, they also have other colors.
- Icelandic Horse
- Sorraia
- Highland Pony
Dun is also a popular color in many other breeds including:
- Quarter Horses
- Mustangs
- Shetland Ponies
- Miniatures
- Paso Finos
- Connemara
And is rare but found in a few lines of
- Welsh Ponies and Cobs (not to be confused with the many buckskins that are traditionally called “dun”)
- Morgans
- Tennessee Walking Horses
It does not occur in breeds like:
- Thoroughbreds
- Purebred Arabians
- Purebred Haflingers
- Purebred Friesians
- PRE Horses
- Purebreds of most draft breeds
Famous Dun Horses
Some of the most famous duns are Quarter Horses and many trace back to one particular stallion, who heads our list of famous dun horses.
Hollywood Gold
Born in 1940, Hollywood Gold was a legendary palomino dun (dunalino) Quarter Horse stallion renowned for his exceptional athleticism and strong influence in the cutting horse industry.
Hollywood Gold’s striking palomino dun coat and powerful build made him a visual stand out but his skill and versatility were the attributes that cemented his reputation. He became a prolific sire, passing on his talent and desirable traits to generations of Quarter Horses, leaving a lasting legacy in the breed.
Although he was put down in 1964 at 24, he was later inducted into the AQHA Hall of Fame in 2007. His contributions to the Quarter Horse breed, particularly as a sire of influential cutting horses, secured his place as one of the most significant stallions in AQHA history.
Today his descendants, many of them cream dilute duns like him, can be found all over the world where they still excel in cutting and reining. One of them was Hollywood Dun It…
Hollywood Dun It
Hollywood Dun It was a buckskin dun (dunskin) Quarter Horse stallion famous for his exceptional performance in reining competitions. Born in 1983, this very attractive dunskin stallion was a son of Hollywood Jac 86 and out of Blossom Berry (source: aqha.com). He was also a great grandson of Hollywood Gold through his sire, and that clearly was where his color and exceptional athletic ability came from.
During his famous and prolific career, Hollywood Dun It earned numerous accolades, including induction into the NRHA Hall of Fame. As a sire, he produced many successful offspring who will carry on the family’s influence in the reining world for many more generations.
Sources:
- Veterinary Genetics Laboratory, UC Davis. (n.d.). Dun Horse. Available at: https://vgl.ucdavis.edu/test/dun-horse
- Dilutes Australia. (n.d.). Shades of Dun. Available at: https://www.dilutesaustralia.net/shades-of-dun.html
