By Phillip Sponenberg, DMV, PhD
Veterinary College, Virginia Tech, Blacksburg, VA 24061
Horse color is an interesting although complicated subject. Part of the complexity can be simplified, but the fact remains that horse color results from the interaction of ten independent effects all combining to give the final color. Fjording are somewhat easier to understand than other breeds, since they are so consistent for some of the factors influencing color.
Fjord horses are consistent for having the linebacked dun gene, this is a dominant gene, and the breed is homozygous or nearly homozygous for this gene, this causes pale body colors, darker pointed and head, and a dark stripe down the back hat continues into the mane and tail. Striping is also usual over the withers, knees, hocks, and sometimes in the forehead. Some very few dun horses are very very striped. A few of these have been reported in Norway, but I know of no Fjord horses in this country are extremely striped.
If any Fjord horses were not homozygous for the dun gene then very rarely could a dark, nondun (bay, chestnut, or black) individual; still occur in the breed. This is expected to be very rare or nonexistent today. Suck dark croup outs would have been more common the past, but breed standardization has favored the linebacked duns that they are now very consistently present. This is represented in genetic shorthand by D for sun and d for the recessive nondun. Essentially all Fjords are DD, so it is more convenient to leave it off the genetic formulas for the breed since all horses invariably have it.
Fjord horses are also consistent for having the lighter muzzle, belly, inside of legs, and over the eyes that is typical of wild animals. This does not mean they are primitive or wild, just that they retain this one aspect of the original color. I am guessing here, but doubt that the breed is completely consistent for these lighter areas. When absent the horses would appear somewhat darker than their herd mates, and might indeed be very attractively colored. This factor is designated by a Spanish term, pangare, and so is abbreviated P for the presence of these light areas, and p for the absence of them. It can be left off for most of the genetic formulas of Fjord horses since it is so uniform in the breed.
Within this consistent linebacked dun color (with the lighter belly) there are some variables. One variable is the color of the points. Most Fjord horses have black (or nearly so) points. The unusual color within the breed is a yellowish linebacked dun with black points. This is the linebacked dun equivalent of bay ( I call these zebra duns). The Fjord horses with reddish to yellowish points are the linebacked equivalent of a chestnut (red dun). The blacked pointed horses with grayish bodies and darker heads are the linebacked equivalent of black (mouse dun or grullo). These mouse duns are called “graa” (grey) in Norwegian, but that becomes very confusing as a direct translation since grey describes and entirely different color of horse in English.
The interactions between zebra, red, and mouse duns are interesting, and can be somewhat confusing. These three colors are caused by two different mechanisms. One choice is black versus nonblack point. The black points are dominant to the nonblack, so the red dun is recessive to either zebra dun or mouse dun. The confusing details is that the red din, though recessive, masks whether or not the horse would have been mouse dun of zebra dub had it had the black pints. Within the black pointed horses the zebra dun is dominant to mouse dun, and both are dominant to red. The confusion occurs when a red dun is mated to a mouse dun and the result is a zebra dub. This is due to most red duns having the independent bay type gene.
This is best understood by using genetic shorthand. Each gene is represented by a letter. Capital letters are dominant, lower case are recessive. Bay is A-, black is aa. Black pointed is E-, red pointed is ee. Most Fjord horses are AAEE, since the zebra dun form of bay is the most common. Some zebra duns within the breed must also be AaEe, and AAEe , since both mouse dun and red dun do occur. Some few would be AeEe, but this pairs two fairly rare genes and therefore the combination would be ever rarer. Mouse duns are usually aaEE since black points are so much more common than than nonblack points. Some few mouse duns are aaEe. Red duns are usually AAee but could be either Aaee or aaee, however these are probably rare within the breed. The confusion comes when a red dun (AAee) and a mouse dun (AAee) are mated. This commonly gives AaEe, a zebra dun. By realizing that the zebra dun vs mouse dun is one question and that the red vs zebra / mouse dun is another it is easy to see how the genes recombine to pick up a dominant gene from each parent, even though each part is exhibiting a recessive color. This the most confusing part of coat color. The rest is easier.
Within the zebra dun group there may be two subtypes. Breeders with experience can shed some light on this problem, but it seems that some zebra duns have extensive black points on the legs, and others have minimal black points on the legs. These two types may be due to two different genes, but this has never been documented. Most Fjord horses are the type with minimal black, but the more extensive should be capable of popping up here and there as a recessive. Do any breeders have experience with this?
In addition to zebra vs mouse dun vs red duns, some Fjord horses also have the palomino type gene. This one is interesting in that it barely betrays itself in most instances. The palomino (or more precisely, the cremello) gene is abbreviated ccr while the absence of it is C . The gene is interesting in that in one dose it lightens red to yellow, but done not affect black. In two doses it lightens all colors to creme with blue eyes. In most zebra dun Fjord horses the cremello gene would cause only a subtle difference in color. These would still be zebra duns, but would be yellower rather that a light orangey tan. Since the breed has been selected to be fairly yellow within the zebra dun group, this difference will be subtle within Fjord horses. On mouse duns the cremello gene in a single dose will be barely be noticed, although it can lighten them somewhat. On red duns it has been it has been a pronounced effect. These have very minimal stripes, are very yellow, and tend to have white points. These are the Fjord equivalent of palomino.
In two doses the cremello gene causes zebra duns to be perlino, mouse duns to be silver smokey, and red duns to be cremello. These are all very similarly colored cream horses with blue eyes, perhaps with minimal striping left over from the dun gene. These are called "kvit" in Norwegian, which translates as white. Whit in English refers to pink skinned white horses with dark eyes, so the translation "white" should be avoided for these horses since they are not truly white. The cremello gene is really a fun gene that is full of surprises. It is an integral and historic part of the Fjord horse breed and should be considered as such. Due to the uniformity of the breed to be pale zebra duns the cremello gene usually skates on through the generations unnoticed - until it pairs up with itself and results in a ble eyed cream horse. These really should be expected in a very low percentage of mating, and are part of the color heritage of the breed.
Other ways in which color of the Fjord can vary are the intensity of the body color. this is simply due to independent modifiers and not to a single gene. Some horses are lighter, some darker. The Fjord horse has been selected to be fairly pale within its color class. For example, zebra duns of the Spanish mustang are sometimes dark enough to be confused with bays. This would rarely if ever occur within the Fjord horse breed. Still, within each color class there is some variation from dark to light.
Another manner is which body color can vary is the presence or absence of black haired mixed into the base color. This usually occurs over the top of the horse rather than further down the body. This is the "sooty" effect, and is probably not due to a single gene but rather to several modifiers. Sooty Fjords are fairly rare, with most being the clear bright body colors.
A few variants occur very, very rarely in other horse breeds, and I am unaware of these in the Fjord horse. One rare variant is for chocolate brown to replace black in the coat. I have only seen a small handful of these. This is expected to be a recessive gene. Another variant is that mane and tail colors varying horses with nonblack points. The vary from light flaxen to red to the lighter colors at least tending to be recessive to the darker ones. Since red dun is fairly rare in the Fjord horse there has not been much selection for mane and tail color within the red duns, and I suspect that most are the middle reddish shade. The final variant that can occur in some breeds is the silver dapple variant. This is very striking in some dark base colors, and I suspect that it is not present in the Fjord. This gene is dominant, and it causes black to be lightened to either a flat brownish color to almost a champagne color. It also lightens black manes, tails, and lower legs until they are a flaxen color. On zebra dun it would be expected to bleach out the mane and tail, nearly bleach the lower legs, and perhaps leave only the backstripe. It have no effect in red pigmented areas. I suspect that it has been eliminated from the Fjord horse by selection since it decreases the contrast desired in the breed.
There are some beautiful Norwegian terms from some of the Fjord horse colors:
brunnblakk = zebra dun. A-CCDDE-PP
lys = light. moerk = dark
roedblakk = red dun. --CCDeePP
graa =mouse dun (literally grey). aaCCDDE-PP.
ulsblakk = zebra dun/ buckskin. A-CccrDDE-PP.
gul = red dun palomino. --CccrDDeePP.
kvit = cremello, perlino, silversmoky ( literally white). --ccrccrDD--PP.