Jan 1998 / Jan 2000 Revised and Photos added Nov 2002 / Feb 2004
Although basic color genetics in the dog are fairly simple, when you get beyond the basics things can become quite complex. The study of color in the dog is also complicated by the fact that many authors have used the same terms for different genetic results, and many breeds use common terms for colors and patterns to indicate quite different appearances. (What we call a sable in GSD's, for example, has nothing to do with what a collie person refers to as sable... and the terms brown and liver are used in many ways). Since questions about color genetics are asked so often, I've tried to put the most reliable information that I have found down in one place. There are just too many variables to keep in your head. Malcolm B. Willis, Ph.D. is my major source. His 1989 book GENETICS OF THE DOG, his 1992 book PRACTICAL GENETICS FOR DOG BREEDERS, and his 1991 book THE GERMAN SHEPHERD DOG, A GENETIC HISTORY are great references. He does an excellent job of explaining the cases where the data is unclear or contradictory.
There seems to be 11 major gene locations that determine the color and pattern of a dog. At each of these locations from 2 to 6 versions of the gene have been identified. Not all of these versions are present in every breed, a fact that simplifies our discussion of color in the German Shepherd Dog somewhat.
1) The AGOUTI series.
This series is thought to contain six variations (or alleles), and in most discussions about GSD color this is the location (locus) we are concerned about. I will list the alleles in order of dominance from the most dominant to the most recessive (meaningm that an allele mentioned higher in the list will be expressed in the physical make up of the dog (phenotype) even when it is paired with an allele lower on the list (the actual versions of the genes present make up what is called the genotype)).
A Dominant Black not thought to exist in GSD's (see #11 below). "A" would also be called dominant self-color.
ay Golden a rarely seen version of sable. "ay" would also be called agouti.
aw Gray what we usually call sable in GSD's (both gray and red sables are genetically the same at this locus... red sables carrying the recessive for redder tan - see the Intensity series below). "aw" would also be called agouti.
as Saddle our common black and tan GSD's (with the variations in tan color controlled by the intensity series below). While there is probably another locus that controls the amount of saddle, it has not been scientifically documented as far as I know.
at Bi-Color while some writers and breeders think that bi-colors are "as" saddles with some other gene controlling the extent of the saddle, others feel that it is a distinct member of the Agouti series. In the real world the results would be the same in either case. A better term for this (and one that would be more consistent with other breeds) would be tan point.
a Recessive Black all data seems to indicate that this is the only form of black that exists in the GSD.
a + a = black (self color)
a + at = bi-color (tan point)
a + as = black and tan (saddle)
a + aw = sable (agouti)
at + a = bi-color (tan point)
at + at = bi-color (tan point)
at + as = black and tan (saddle)
at + aw = sable (agouti)
as + a = black and tan (saddle)
as + at = black and tan (saddle)
as + as = black and tan (saddle)
as + aw = sable (agouti)
aw + a = sable (agouti)
aw + at = sable (agouti)
aw + as = sable (agouti)
aw + aw = sable (agouti)
I left "B" and "ay" out of the chart. They are exceedingly rare, if not nonexistant in German Shepherds. You can easily see how they would work if they did turn up.
There are a few practical conclusions that you can draw from this chart:
sables can carry any other color and still be sables
a sable that has two "aw" genes can only pass on "aw" to its offspring... since "aw" will dominate all of the other possible genes the puppies could inherit from their other parent, they will be sables
two black and tans can never produce a sable (since if one of the parents had an "aw" gene to pass on, it would itself be a sable
two blacks can only produce blacks
One of the confusing things when discussing coat color genetics is that even though we tend to call sable and black and tan colors, they should more properly be called coat patterns. In addition, there are other gene series that effect both color and pattern that are inherited independently of this Agouti series.
Although ut has not been documented by scientific study, it seems clear from anecdotal evidence that the expression of the promary "color" generated by the genes at the agouti location is modified by other genes at other locations (and thus inherited independently), and even by the companion gene at the agouti locus. It seems that sables that are aw + a (they carry the recessive for black) will be much darker than the average sable (sometimes being called black sables). In addition, the overall appearance of the dog is influenced by the color of the undercoat. Unfortunately, I do not have any documented information on the possible genetics of undercoat color. I have seen very light tan (almost white), darker tan, reddish, gray, and black undercoat
(Note: White is not part of this series at all. Questions about white being recessive to black, etc., have no real meaning since it is something determined at a completely different locus.)
2) The BLACK series.
This locus controls the ability to produce black pigment in the coat and skin (nose, pads, etc.)
B Black pigment the most common in GSD's.
b Liver Pigment this allele creates dogs with no black in their coat or skin (they have brown hair, noses, and pads). These dogs are commonly called "Livers". Contrary to earlier beliefs, this color does not seem to be linked to any genetic defects.
It should be clear, from the fact that this factor is controlled by genes at an entirely different location, that you can have a liver that is genotypically a black, a bi-color, an black and tan, or a sable. These livers will look somewhat different from one another, since what has been effected is the black pigment and the black pigment is distributed differently in each of those patterns.
3) The COLOR series.
This is the critical series in determining the nature of white in all breeds, including GSD's.
C Color Factor most common in GSD's and leads to our sable, black and tan, bi and black.
cch Chinchilla not confirmed in GSD's, but could be a sourc of some whites when cch/cch is present with ay/ay... it is certainly involved with variations of white in other breeds.
cd White leads to white coated, dark eyed dogs with black noses and pads.
cb Cornaz leads to white coated, blue eyed dogs, not thought to exist in GSD's.
c Albanism white coat, pink nose and pads.
(note: from this information it is clear that a white can carry any of the AGOUTI series, which will surface if it is bred to a dog with the color factor "C".)
4)The DILUTION series. The effect of these alleles depends on what you have at other locations.
D No Dilution no effect.
d Dilution black "B" becomes blue and liver "b" becomes fawn. Contrary to earlier beliefs dilution does not seem to be linked to any genetic defects (except an overall loss of color intensity).
5) The EXTENSION series.
Em Black Mask most common in GSD's.
E No Black Mask does apear in GSD's sometimes.
ebr Brindle exceedingly rare in GSD's, if it still exists at all (see #11, below).
e Fading causes black to fade over time and is rare.
6) The GRAYING series.
G Graying born black, turns blue, not thought to exist in GSD's, but the predominant color in Kerry Blue Terriers.
g Non Graying born black, stays black, all GSD's are thought to be "g".
7) The INTENSITY series.
INT Lightest tan (cream).
intm Medium tan tan.
int Darkest tan red.
These alleles lead to our "black and creams", "black and tans", "black and reds", and the common variations in sables.
8) The MERLE series.
M Merle seen in collies, Austrialian Shepherds, and Australian Cattle Dogs (mottled grey, black, tan, often with blue or mismatched eye color).
m Non-Merle all GSD's seem to be "m", non-merle.
9) The SPOTTING series.
S Solid Color all GSD's seem to be "S".
si Irish Spotting
sw Extreme White Piebald
10) The TICKING series.
t Non Ticking all GSD's seem to be "t".
11) The DOMINANT BLACK series.
K Dominant Black masks the genes at the A locus.
k (not named) recessive that allows full expresion of the genes at the A locus.
Note:(11) is based on recent research (I believe still unpublished), most notably by Stacy Prober in Racing Greyhounds, that seems to indicate that Dominant Black is not part of the Agouti series, and that brindle is not part of the Extension series. They seem to be part of a new series she calls Dominant Black (or K). In this case, it would appear that all GSD's are kk (although there are a few unconfirmed reports of k(br) k(br) in the distant past of the breed. For all practical purposes, the existence of this series may be meaningless when we are talking about German Shepherds... the results would be the same in either case. In other breeds this is a significant distinction, however, and seems pretty well supported.
The light colored hair scattered down the back of many of our black and tan GSD's seems to be the result of a locus that has not been given a name. What studies have been done seem to indicate that a simple recessive is at work. Since the degree of "salt and pepper" varies greatly, there may be more than one allele in this series. I have not found any information on the genetics behind the white spots sometimes found on the chest of our dogs, nor white tipped tails or hite feet. Perhaps all GSD's ae not (S) in the SPOTTING series.
Additional photographs to help visualize some of these colors/patterns in actual German Shepherds follow below.
Sable puppies go through many changes between the time they are born and when they become adults. The pictures below show the same puppy at 3, 5 1/2, 11, 13, 17, and 25 weeks, and give some idea of the change that occures. Sable puppies are usually quite dark at birth, become very light as they lose their puppy coat, and then begin to darken once again as their adult coat comes in for the first time. As adults, sables tend to change in appearance after each shed and growth of a new coat. As a rule, they become darker overall as they get older.