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Colour Coat Genetics - Dun
  

WHAT DOES A DUN LOOK LIKE?
A DUN is similar in colour to a BUCKSKIN, bur generically, this is where it stops. Like BUCKSKIN, the body will appear yellow, golden, light ran, or a deep tan than is similar to peanut butter. The mane and tail will be black, and the lower legs are black to some degree, usually in the form of socks or stockings but are sometimes contained within the pastern area only. The tips of the ears will be black or dark brown. The presence of the black points means than at least one parent must also carry the BLACK gene. Unlike a BUCKSKIN, a DUN has some or all of the DUN characteristics - a dorsal stripe, zebra stripes on the legs, and striping over the withers. DUN characteristics have also been observed behind the ears and on the neck. DUN, therefore, is a 'package deal.' It must have the DUN characteristics as well as the body colour being diluted to any of the colours mentioned above or some variation of them. Oftentimes, an owner will describe the colour of the mane and tail of a horse as 'dun.' However, if the horse is a DUN, the obvious colour of the mane and tail should be listed as black. DUN as a colour choice is a combination of colours and characteristics on the coat-not a colour itself.

Some DUNS may have darker hair covering their body to some degree. This is due to the 'smutty' or 'sooty' gene and may affect the face and back. The 'smuttiness' affecting the face will often give the horse 'masking' to some degree that is often confused with the very dark to black head of the GRULLO. (See GRULLO).

WHAT ARE THE COLOUR GENETICS OF DUN?

A DUN is the effect of the DUN gene on a BAY base colour. Sometimes DUN and GRULLO are confused with one another. Genetically, there are differences between them. (GRULLO is the effect of the DUN gene on a BLACK base colour.) It is the inheritance of the DUN gene from at least one parent that gives both the diluted appearance as well as the DUN characteristics.

Sometimes a horse will carry the CREAM DILUTION in addition to the DUN DILUTION, which means this variation of DUN may produce both DUN and CREAM DILUTION (PALOMINO and BUCKSKIN) offspring. This DUN may not appear any differently than a DUN which does not carry the CREAM DILUTION. It is commonly the result of one parent being CREAM DILUTED and the other being DUN DILUTED. However, one parent may carry both dilutions due to specific ancestors in a specific bloodline. (The stallion, HOLLYWOOD GOLD, is a prime example. He was registered as DUN but was clearly a RED DUN with the gold body colouration of a PALOMINO with a flaxen mane and tail. However, he also had a distinct dorsal stripe and distinct zebra stripes on the legs that were almost chestnut in colour, thus exhibiting both CREAM and DUN DILUTIONS.) These DUNS must be treated in the same way as one would a BUCKSKIN when considering the potential colour of the offspring; a DOUBLE DILUTE foal may result if this variation of DUN is bred to another parent which carries the CREAM DILUTION.

HOW DID THIS HORSE GET THE DUN DILUTION?

At least one of the foal's parents contributes one copy of the DUN DILUTION gene. This parent will most likely be a DUN, RED DUN or GRULLO. There are a few exceptions. For example, some pedigrees may show a parent or ancestor as being registered BLUE ROAN but is actually GRULLO-ROAN or as being registered RED ROAN bur is actually DUN-ROAN or RED DUN-ROAN. The colours may appear to 'hide' the DUN DILUTION or appear to skip generations, oftentimes leading to the erroneous assumption that DUNS can be 'crop outs.' The same holds true if a parent started out as a DUN, RED DUN, or GRULLO but turned gray (in the event of a gray parent), whereby the colour was amended to reflect this on the certificate of registration. Some pedigrees may show a horse registered as BUCKSKIN but may, in fact, have been a DUN. In any event, DUN is a dominant gene, which means at least one parent must always be a type of DUN, whether registered as a ROAN type or has turned GRAY. But being dominant does not necessarily mean dominating in that, merely breeding a DUN DILUTION horse to a horse of any other colour will guarantee a DUN DILUTE horse.

Sometimes, a DUN horse is the result of two DUN DILUTION parents. This includes any combination of crosses between DUNS, RED DUNS, GRULLOS, or horses registered a colour (erroneously or not) that is carrying the DUN gene as well as at least one parent that expresses the BLACK gene. If each parent passes on one copy of the DUN gene, the result is a horse that is homozygous for the DUN DILUTION. This means that this horse will pass on the DUN gene to its offspring 100 percent of the time, regardless of the colour of the other parent.

WHAT ARE SOME OTHER ASPECTS WE NEED TO KNOW ABOUT DUNS?

It is possible for a DUN to express the ROAN gene. Generically, this is called a DUN-ROAN. This may happen if one parent carries the roan gene and is bred to a parent that carries the DUN DILUTION as well as the BLACK gene. Since DUNS may be light in shade, the ROAN may not immediately be recognized. At present, AQHA does not have a separate colour choice of DUN-ROAN. For registration purposes, the horse is registered as the base colour of DUN. AQHA then indicates the ROAN characteristic under the markings area of the registration certificate with the phrase "CARRIES AND EXPRESSES ROAN GENE."

Some GRAY horses may have started out as DUN, These horses still retain the colour genetic information to pass on the DUN DILUTION gene and produce DUN DILUTION foals regardless of the colour of the other parent. Some DUNS that are turning or have turned GRAY may not easily be recognized as such, since the coat is already light in shade. A DUN usually shows lighter hairs in the face (sometimes called 'silvering'), specifically around the eyes and muzzle. Any true white face markings the horse was born with will blend into the face as the gray progresses. There may be graying in the black of lower legs. The tip of the tail will turn a pale, gold to silver colour, eventually becoming lighter from the bottom up as the horse ages. The rest of the coat may have gray hairs scattered throughout (again, this may not be easily noticed), but the coat may also be unaffected for years, even retaining the DUN characteristics as it GRAYS. (See GRAY)

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