Genes

So what does the dun gene do? It is a dilute gene that changes the coat color characteristics in equines. Some schools of thought now think it could be a modifying gene instead, but either way, it is a gene that affects the coloring. It is sometimes called a primitive gene because it is believed to have been around as long as horses have been around. It is found with more frequency in some breeds than others. It is very prevalent in the Fjord, Mustang, and Quarter Horse breeds – but very rare to non-existent in the TB and gaited horse breeds. The gene can manifest itself on all coat colors and often appears with other modifying and dilute genes. It generally dilutes the body color, but leaves the points a darker shade of the same color. It is also responsible for the primitive markings, often called dun factor markings, you find on dun gene horses. It is a dominant gene, which means one parent must have the gene to pass it down to the offspring.

The first, and most notable marking is the dorsal stripe. This is a darker line that runs the entire length of the back of a horse and continues on into the tail hairs. It can be a wide or narrow line and it might be wider at the hip area than it was at the wither area. It might be intersected by other dark lines (generally called barbs or transverse striping.) It should be unbroken unless the horse is spotted, and it is defined and apparent all year. The dorsal stripe is the color of the horse’s points. The dorsal stripe is ALWAYS present if the dun gene is present.

There are several other characteristics as well, but these may or may not be evident on a horse that has the dun gene. Generally there will be at least some, and perhaps all, of the following markings on a dun gene horse.

A. Cobwebbing – This is an interesting pattern that appears on the horse’s forehead area. It is a circular pattern of darker hairs that resemble’s the shape of a spider’s web.

B. Face Mask – This marking can range from a little bit of color to completely covering the face in the darker point color of the horse.

C. Transverse Striping – These markings run perpendicular to the dorsal stripe on the horse’s back and are sometimes called barbs.

D. Shoulder Bars – These patches of darker color are found around the shoulder and neck area of the horse. Some will have very dark markings and could have two or more patches of color on each side.

E. Mottling – This is one of my favorite markings and it is generally found at the top of the leg points. You will see random spots of color above the horse’s stockings on his back and/or front legs.

F. Leg Bars – These are the stripes you see on the back and front legs of a horse around the knee area. Sometimes they are called zebra stripes and they cross the legs from side to side.

G. Ear Tipping – This marking is just a darker tipping on the horse’s ears. You will also sometimes see that the ears are lined with the point color of the horse.

H. Frosting – You will sometimes find frosting at the top of the tail and in the mane of a horse carrying the dun gene.

As I stated earlier, the gene is present on all the different coat colors and patterns and there is a name for each color occurrence. A chestnut/sorrel horse with the dun gene is called a red dun. A bay horse with the dun gene is called a dun or a bay dun. A black horse with the dun gene is called a grullo or grulla (pronounced grew-yo or grew-ya.) If the gene is present with other modifies, then the color would be called that name with dun (ie. palomino dun or dunalino, spotted dun, gold champagne dun, roan dun, etc.) The dun gene patterns are fairly consistent and once you become familiar with seeing them, you can usually spot them quickly. There is no test available at this time to identify the gene, however there is progress toward offering one in the future. So for now, we have to rely on visual observation, lineage knowledge, and offspring results to identify dun horses.

So where does all the confusion come into play? Usually the markings are very apparent and it is easy to spot a dun gene horse (as in the pictures of Future above.) But that is not always the case. A dun gene horse must have a dorsal stripe. Also, some of the above characteristics should be visible, but they are not always so easy to see. It becomes confusing when you have a smutty coat. Often, the smutty coat will appear to have a dorsal stripe along the back of the horse. This false dorsal does not, however, run into the tail hairs. It is usually visible during the winter months, but not in the summer. And, it is usually not defined like a true dorsal is. The darker coloring seems to fade away into the horse’s coat. Also, a false dorsal occurs when a foal is shedding his foal coat (see picture above left.) Sometimes a false dorsal stripe is very convincing, even to someone familiar with the gene and its markings. Because of this, it is important to find some of the other markings on the horse you suspect is a dun gene horse. Red duns are one of the harder colors to confirm because you can see the dorsal, but quite often you cannot see any leg bars. Look for darker leg points on a red horse. Also, they usually will have shoulder bars, even if they are light in color. I have seen red dun horses with very obvious leg bars, however, I have seen more with no visible leg barring at all. But all the ones I have seen do have neck bars to go along with the dorsals. When there is a question, look to the dam and sire. If one of these is an obvious dun, then there is a possibility this horse is a dun. If neither the dam nor sire were duns, then it isn’t possible that this horse is a dun. The pictures to the left are of Dusty’s dorsal stripe, neck bars, leg bars, and darker points. As you can see, his markings are not nearly as obvious as Future’s markings are. Sometimes you have to look hard to see them on the red based horses. Dusty’s leg bars are all but invisible in the winter when his coat is darker. Even his dorsal stripe is more difficult to see.

In the AQHA where the dun gene is readily found, the most rare color is the grulla, or black dun. Out of over 155,000 horses registered with AQHA in 2002, just over 1200 (or 8%) were grullo. There were a total of just under 11,000 dun gene horses registered that year.* The number of grulla horses is on the rise because breeders are now breeding specifically for that color, but it is still a difficult color to produce. Our breeding experience is with AQHA horses and breeding for the grullo coloring. The best chance to produce a grullo is to breed grullo to grulla. Unfortunately, we do not have that luxury in the foxtrotting breed because until now, there were no attempts to find two lines to breed together. All of the known dun breeding has been dun to non-dun. When breeding this way, there is only a 50% chance of getting a dun of any color, let alone the black based dun. So the numbers are increasing very slowly. We intend to eventually breed dun to dun, which will give us an approximately 75% chance of getting a dun gene offspring, which are much better odds. And the homozygous foals we put on the ground will eventually throw dun gene foals 100% of the time, even when bred to non-dun gene horses. We intend to keep all of our breeding quality fillies to breed to Future, but we would eventually like to breed only our black based horses to Future in the hopes of throwing the dun colors we prefer – grullo and bay dun.

The dun gene is not common in the gaited horse world. Until recently, many believed it was not present at all. We began our search for dun gene foxtrotters in 2002. We found a few owners who thought they had dun foxtrotters, but upon inspection, we found those to be smutty instead of dun. We had all but given up when we found the Gem Lady Dawn line, and Future. It was somewhat difficult at the time to convince the foxtrotter world that this line really was a dun gene line, but people are beginning to understand the gene now and accept that the dun gene does exist in the breed. In recent months, 2 different lines have been found in the Missouri Fox Trotting breed that carry the dun gene, and more than likely there are others. We do know of a line that goes back to a 3 G’s mare, and a line that goes back to a Gem Lady Dawn mare that both carry the gene. The 3 G’s line is located in the MO/AR area and the Gem Lady Dawn line is in the OH area. And of course there is a stallion from each line located in TN at our farm. The numbers are now creeping up because there is finally a standing stallion in the AR area and several dun gene foals have hit the ground in the past 2 years. This stallion sired Dusty and Maxi. We will see Dusty’s first small foal crop in 2006, and in the coming years, there will be more and more dun gene horses showing up at shows and other events. We expect the trend will follow those in the other registries and the demand for these horses will only increase due to the beauty of the markings.

We were lucky enough to find a stallion from each line to stand at The Dun Factor E. We have researched the lines and found that they are completely unrelated as far back as records can be traced. In our breed, that is unusual no matter what the color because the gene pool is relatively small. The dun gene does have a homozygous form, but it is very unlikely that there are any homozygous dun Missouri Fox Trotters at this time as we have not found any crossing of the two lines mentioned above. To have a homozygous dun, both sire and dam must be dun and both must pass the dun gene down to the offspring. Since there is no test for the gene and the visual effects are the same for both homozygous and heterogous, the only way to verify a homozygous dun would be through the foals. If the horse puts dun gene foals on the ground every time it is bred, then the horse would be homozygous. It is our hope to put some homozygous dun Missouri Fox Trotting horses on the ground in the coming years by crossing the two known dun gene lines through our stallions’ progeny. Since Dusty is the oldest, we are breeding him to our mares now. These mares have been very carefully selected to cross well with Dusty and hopefully put better quality foals on the ground than either parent alone. We intend to keep the dun fillies we believe will cross well with Future for the foundation stock of homozygous duns in our breed. It is our hope that these homozygous duns will be bred, and their resulting dun foals will be even better representatives of the breed. It is the responsibility of all breeders to improve the breed with higher quality foals than the sire or dam alone. We hope the foals we put on the ground will be the beginning – not the end – of quality dun gene breeding of Missouri Foxtrotting horses.

There are many breeders in the other breed registries experimenting now with combinations of the dun gene and other dilute and modifying genes. Many of these are breeding for a particular color of dun – the grullo roan for example. There is some opposition to this, however, as some believe mixing all of these genes will eventually breed the true dun out of existence. But it seems like a logical path for color breeders to take as we are always trying to find a nitch and something unique that will set us apart from the rest. Eventually, there will be enough dun breeders in the foxtrotting breed to also tempt breeders to combine genes and breed for uniqueness. Still – it all goes back to the horse. There must be a quality horse under that beautiful color or we are all wasting our time.

If you have any questions about the dun gene, please feel free to ask. I have several articles and have located many sites that help clarify this information that I would be happy to pass along to those who are interested. The information posted here if very basic and useful to those with a casual interest in the gene and those who are not familiar with it at all. I’ve tried to put the information in layman’s terms, rather than the technical wordings found in other articles. Genetics can be confusing due to the language used – which is more confusing, at times, than the actual concept. Also, please contact me if you know of another line of duns in our breed. We are trying to build a data base of dun gene foxtrotting horses and any information would be appreciated. If you are interested in becoming a dun gene breeder, we would be happy to share any information you need.

*AQHA stats taken from:
Getting Informed…About Grullas by Kristy Enloe

We came to this breed from the AQHA. We are used to breeding for color and understand the importance of getting it correct for our clients. We study color genetics and try to stay on top of the current trends, beliefs, available tests, and changes in this field. Because of this, our clients can be assured that our horses are the colors we say they are and our horses have been tested to verify our claims whenever a test is available. There are several breeders out there who are also current on the new data and advertise their horses accordingly.

However, there are many more who do not understand the genetics and claim to have horses that are this or that color, but they are not. There are stallions advertised as cremellos that are really grey and they are putting palomino foals on the ground that are also misrepresented as chocolate palominos, when in fact, they are palominos going grey. There are stallions advertised as carrying the silver dapple gene that do not. There are many horses marketed as carrying the creme gene that possibly do not (as in smoky blacks.) I know of owners claiming to have dun gene horses who actually have smutty horses instead. Because of this, if you are looking for a particular color (and especially if it is rare), it is important for you to do your own homework. Many breeders even go so far as to have their horses tested, but they misinterpret the results. Ask for the testing results and read them yourself. Below you will find a breakdown of the codes they use for the different colors.

C/C or cr/cr means the horse does not carry the creme gene (ie chestnut)
C/Ccr or Cr/cr means the horse carries 1 creme gene (ie palomino)
Ccr/Ccr or Cr/Cr means a double dose of the creme gene (ie cremello)

e/e means you have a red horse – no black (ie chestnut)
E/e means you have a black horse that also carries a red gene – the horse will look black
E/E means you have a HZ black horse that can only throw the black gene – will never have red foals

a/a means the horse does not carry the agouti gene and is not capable of throwing black points on foals alone
A/a means the horse has one agouti gene and can throw black points 50% of the time
A/A means the horse is HZ for agouti and will always throw horses with the black restricted to the points. This horse can never throw a black, smoky black, grullo. blue roan, or any other variation of a black horse.

g/g means the horse does not carry the grey gene
G/g means the horse is grey and will throw grey 50% of the time
G/G is HZ for grey and will always throw grey foals

d/d means the horse does not carry the dun gene
D/d means the horse has 1 copy of the gene and will throw it 50% of the time
D/D means the horse is HZ for the dun gene

So – Future is technically ww gg cc aa Ee Dd – which means he is not white, will not turn grey, doesn’t have any cream, does not have any agouti, has 1 red and 1 black gene and 1 dun gene. Or – he is a black horse with a dun gene but he is also capable of throwing red horses because he does not have 2 copies of the black gene. For short – he is Ee Dd.

Also – on a different note – we have a lot of grey in our breed and we know that most grey horses start out dark and lighten with age. However, the palomino is an exception to this. A palomino horse greys by getting darker for a while. It generally starts on the legs and works its way up and it is usually also on the face. The horse will appear to be almost a chocolate color for a while and then the horse will begin to get the grey hairs. If you are considering a palomino advertised as chocolate, you should have the horse tested for grey to avoid disappointment later. We have a few stallions out there advertised as cremello that are actually cremellos gone, or going grey. Those palomino offspring are very possibly going grey and should be tested if you want to keep the color. I am sure this occurs in all the breed registries that have cremello stallions.

As I said before, you must have at least one dun parent when breeding for dun foals. Your chances of getting a dun foal are 50% when breeding dun to non-dun. Below you will find different sceneries to follow depending on the color dun foal you hope to get.

Red Dun – A red dun is beautiful and can range from an almost pink cast to his coat to an almost chestnut color. He can have an almost flaxen mane and tail to a mane and tail that look almost black. His points can be very light and almost invisible to very very dark red (again looking almost black.) Our stallion, Dusty, is a red dun. A red dun horse is simply an e/e horse with the dun gene. This means there is no black, no grey, no white, only two red and one dun gene. Every chestnut or sorrel horse out there is e/e. All you need to do is add the dun gene and you are there. This is by far the most simple dun color to get, especially since we have so many red based horses in our breed. We can get a red dun out of any of our mares bred to either of our stallions since we do not have any HZ black horses on the farm. If the base color of a mare and the base color of the dun could make a sorrel foal, then you can get a red dun from that same breeding.

Palomino Dun – Some people call this a dunalino, but the genetics are the same. He is basically a palomino horse with the dun gene – two red genes, one creme gene and one dun gene. A palomino dun has a lighter body coat color than your average palomino coloring and the tail has silver/grey/red hairs running through it as a result of the dorsal stripe running into the tail hairs. He should have darker points and you should be able to see leg bars. Of course he will have a dorsal stripe too. Quite often these markings are easy to miss, especially in the foals, and they are often misregistered as palominos. Dusty’s sire – Playboy’s Country Boy – is a palomino dun. We are hoping for a palomino dun or two from breeding Dusty to our palomino mare, Hickory. They both carry the red gene, Dusty has the dun and Hickory has the creme. Of course we could get a red dun out of these two as well.

Dun or Bay Dun – Now we are getting a little more complicated. A bay dun is either an E/e or E/E with an agouti gene and a dun gene. So this horse is black based. The coat color is usually a golden or a light brown, but can run the full gambit of shades for a bay horse (muted.) The points are black or dark brown. We do not have the genetic material to make a bay dun on our farm unless we have a hidden agouti gene in any of our red based horses. We do like this color, however, and would like to breed for it in the future.

Buckskin Dun – Genetically this one is even more complicated. You have to have an E/e or E/E horse with agouti, creme, and a dun gene. A buckskin dun generally looks like a buckskin with a shade lighter body color and he has the dun factor markings. A buckskin dun is often confused with a sooty buckskin and most of the times when someone thinks he has a dun and does not, it is either a buckskin or a bay. This is generally because the horse is also sooty and the sooty markings can mimic the dun markings very well.

Grulla or Grullo – This is my favorite dun color and it is sometimes called Black Dun. It isn’t genetically complicated – just an E/e or E/E horse with a dun gene. But for some reason it is rare and hard to get. The terms are used interchangeably, but the “o” ending is generally used for a colt and the “a” ending is used for a filly. This color changes in intensity depending on the time of the year, but looks a lot like a roan from a distance. Up close you can see that there is not a mix of white and black hairs, but all the hairs are one color. The points stay dark and the body color ranges from a silver to a very dark, almost black, color. You will often see grulla coats with a brown cast to them in the winter. But they always shed out to a beautiful blue color in the Spring. Both Maxi and Future are E/e and D/d.

Others – You can also have spotted duns, champagne duns, roan duns, etc. The gene can be present with any other dilute gene or modifier. You can find cremello or perlino duns as well. In some of the other registries, the trend now is to mix the dun gene with these other modifying genes to see just what fancy colors they can get. I saw a beautiful roan grullo stallion not long ago and he looked like a shiny silver medallion. I would like to see some champagne duns in the future because I think that gleaming color would be accentuated by the dun markings. But for now we are content with just helping to bring the numbers up with the standard dun colors and only adding the creme gene from time to time. We will leave the more exotic colors up to the next band of breeders of this beautiful color in our breed.

Breeding to get the Grulla coloring:

The best and easiest way to get your grulla is to buy one already on the ground if you can find one. It is by far the quickest way and may turn out to be the least expensive way as well if you have to pay to AI to a dun stallion several times trying to get the elusive grulla coloring out of your mare.

But if you can’t wait or can’t find one already on the ground, your best bet is to breed grulla to grullo. You will have around a 70% chance of getting a grulla foal. I know in our breed that is next to impossible. As far as I know, I am the only one who actually has a grullo stallion from one bloodline and a grulla filly from another that can be cross bred without the worry of inbreeding problems. And mine are still a couple of years away from that breeding.

So the next best thing is to breed a HZ black mare to a dun stallion of any color. The mare will always throw the black and all you need to do is wait for the stallion to throw his dun gene for you and you will have your grulla. Of course it is also difficult to find a HZ black mare in our breed. I know they are out there, but they are few and far between.

So ok, the next best chance is to breed a black mare that is E/e to Future who is also E/e plus D/d. It will take a while, but this match will throw grulla foals. One has to throw the black gene and Future has to throw his dun to get a grulla. It will really be lucky if both throw black and he throws his dun because then you would have a grulla foal that is HZ black and that would be a great asset to a breeding program.

You can also get the color with a bay or buckskin as they are also black based. But if they throw the agouti, then you will not have a grulla as the black will be restricted to the points only. And you can get a grulla breeding a red mare to Future, but the statistics aren’t good and it will take several tries to get a grulla from that match up.

Now you see why it is less expensive and much quicker to buy one already here. It is our hope to eventually bring our breeding program around to all grullas if possible or at least 2 grulla mares and Hickory and Sera. So if you have the time, sit back and relax. Let us do the work and you can pick from the pretty foals that hit the ground at our farm in the coming years.