Yes, because sable or black and tan puppies, which have occasionally been born in recent years to two solid black parents, continue to surprise breed enthusiasts and experts. Aafter all, a knowledgeable shepherd dog fancier knows that this is supposed to be impossible! Whether they have a deep understanding of genetics or simply follow the charts explaining “what can come from what”, or rather, what “should” come from what, they know that from two completely black geman shepherds may born only completely black puppies. So, what is going on?

Well, there are two possibilities: either a random genetic mutation occurred, which isn’t strictly impossible, as such things happen all the time, though it is highly unlikely that “that specific” mutation would occur in “that specific” breed or, more likely, there was an introduction of “outside” DNA. We don’t know exactly what it was, we can only speculate. One hypothesis points to the Belgian Shepherd, given that the two breeds are closely related, share common origins, and have often been crossbred (even if the offspring were generally classified as mixed-breed). Others mention Russian breeds, since the dogs in question often originate from that region, while some claim that the dominant black trait has always existed in certain bloodlines. Of course, the Belgian Shepherd isn’t the only breed carrying the gene responsible for the phenomenon we are discussing, it could just as easily be a mixed-breed dog, provided it possesses “that gene.” In any case, even if it did stem from an outside introduction, something that remains unproven, any such influence would become negligible after just a few generations. The dogs revert perfectly to the breed standard, and DNA tests confirm them as 100% German Shepherd, so there is no issue.

So, before diving into the genetics itself, I’d like to take a brief detour to explore these “clandestine introductions”. People often hint at them, but can such a thing really happen? Well, it certainly happens, it has happened, and it will happen again. Parentage checks aren’t always performed, selected parents with DNA Stocked and certified pedigrees aren’t always used, and the offspring aren’t always registered as “selected” dogs, so yes, it happens, and in happens across all breeds. Sometimes it’s intentional, sometimes accidental, sometimes it’s discovered, sometimes not, sometimes even the dam’s owner doesn’t notice. However, if there are any doubts, there is always the parent-offspring DNA test to verify that everything is as it seems to be. It is precisely through litter checks, sometimes mandated by the Kennel Club, sometimes requested voluntarily by owners, that various cases of dog excanges come to light.
In fact, staff at a genetics institute told me that the most common scenario is a litter sired by two or more fathers. You see, not all available ova are necessarily fertilized at the same time, if the female mates with different dogs at different intervals, some unfertilized ova might be fertilized by a second (or even third) partner. An owner might return from the planned mating convinced the female is already pregnant and leave her with their own male(s),  if she mates again, she can end up with offspring from different fathers. Sometimes this stems from naivety, but other times it is done on purpose, an attempt to secure more puppies for sale in case she hadn’t conceived or only a few ova were fertilized.

That said, it follows that if any “othergenetic material” was introduced, it wasn’t necessarily done intentionally, and who knows how long ago it happened. Far be it from me to cast aspersions on anyone or anyone’s dogs, who knows me understand my stance, dogs should be healthy, in type, and have a good temperament. If those criteria are met, I have no issue with it, even if other genetic material found its way in over time. After all, as I’ve said, it happens constantly and always will. In any case, regardless of how these colors we’re about to discuss are achieved, they remain colors of breed’s standard, so everyone can rest easy. This article is not an exposé or an attempt to defame anyone, it is simply a genetic explanation of what occurs, intended to satisfy the curious and dispel any doubts. After all, whenever this happens, a debate inevitably ensues,or at least it did in the early days. By now, people have likely gotten used to it…

Let us now turn to the genetic series relevant to us specifically, those governing coat color in dogs.

First, let’s recall that the color BLACK is produced by EUMELANIN, while the color RED (fawn) is produced by PHEOMELANIN, these are the only two types of pigment that color a dog’s coat and body. The interplay of these colors, varying in intensity and distribution—combined with white markings (which aren’t actually a color, but rather the total absence of pigment), creates the infinite universe of possible dog coat colors, all orchestrated by just a few DNA loci.

THE AGOUTI SERIES

The most important genetic series, the one that determines what color our German Shepherd will be, is the famous AGOUTI series. It contains the alleles that dictate the distribution of black hairs, fawn hairs, or hairs with alternating bands of fawn and black across the dog’s body. There are 6 alleles in this series, although only 4 are found in the German Shepherd

-A^y (from “yellow“) It is the primary, most dominant gene, the fawn (or fawn with black overlay) gene. theorically, this is the only one the Belgian Shepherd should possess (even when we see them looking black, you will understand why later), whereas it is absent in the German Shepherd. the example shown in the photo is a Belgian Malinois.

–A^ys (from “shaded yellow“) is the second in the order of dominance, this is the sable (or “shaded fawn“) coat, the only one, along with the Ay fawn, that the Belgian Shepherd theoretically possesses (even when it appears black,you will understand why later), but which is absent in the German Shepherd. Indeed, the example shown in the photo is a Belgian Malinois

–A^w (w from “wild“), also known as Agouti, grey, sometimes. It is called “wild” because it is the wild-type coloration, indeed, it is the color found in their wolf cousins, but it also appears in many other wild animals because it offers better camouflage. This color is frequently found in working lines, although, as we shall see, there are also Agouti dogs in show lines.

–A^s (s from saddled) The Classic  Show Line Black and Tan, with saddle retiredback from Shoulders.

–A^t   (t from Tan Point) It is the classic black-and-tan, beyond that, working lines generally feature the classic bicolors with “socks,” “near-total” blacks with minimal tan, or tan markings like a Doberman’s or even less. Even when they have more tan, however, they certainly lack the “saddle” markings seen on the show dogs in the example photo. Given the partial relevance of this point to the mystery the article aims to unravel, we will return to it in detail shortly

–a The most recessive of all, our famous “true” black, the only black a German Shepherd should have. Being the most recessive in the series, producing black dogs requires the subject to possess two ‘a‘ alleles at the agouti locus (referred to as being homozygous for ‘a‘), in other words, the ‘a‘ gene must have been inherited from both the mother and the father.

A BIT OF HISTORY

At one time, a fifth allele called A^s (for “saddled”), was thought to exist. However, once the entire Agouti series was interpreted and sequenced, it became clear that black-and-tan dogs are actually all A^t,  the only difference lies in the extent of the tan, which is determined by genes that have not yet been identified. Indeed, black-and-tan German Shepherd puppies are usually born almost entirely black, as they grow, the black recedes from the extremities, giving way to tan. The degree of this recession varies quantitatively, if a dog that is almost entirely black mates with a dog that has a minimal saddle (since some individuals have very little black on their backs), the puppies generally tend to have a saddle size somewhere between that of the two parents, with the parents’ own saddle sizes representing the two extremes. The animation illustrates how the black recedes. Later, the “RALY” gene was discovered. It appeared to influence whether or not the black receded, but it was subsequently observed that the black did not always recede in the presence of this gene, it was likely a coincidence that all the dogs studied (Beagles) happened to carry it. Thanks to modern advanced technologies, the Agouti series is now recognized as having six alleles. We now distinguish between A^y and A^ys for fawn/sable dogs (whereas previously only A^y  was known, and all fawn dogs were thought to be A^y with modifiers regulating the intensity of black tipping). We also distinguish between “Blackback” A^t (dark black with limited tan in specific locations, like a Doberman) and “saddle tan” (A^s), where the black recedes from the extremities to leave a saddle of varying definition. Though this extent is regulated by other factors we won’t go into here, and which perhaps are not yet fully understood even by geneticists. A^s is dominant over A^t, but the dominance is incomplete, consequently, intermediate A^sA^t phenotypes fall somewhere between having very little tan-point coloration and being almost entirely black, depending also on modifier genes. These intermediate forms are known as “Creeping Tan” like the dog shown below.

Let us speak a little more about extent of black and tan coloring in our dogs.

Look at the muzzle, where there is NO black mask. In the German Shepherd, the breed standard mandates a black mask, determined by a different genetic series that we need not discuss here, but it is omitted in this animation to clearly show what is happening on the dog’s muzzle. Of course, a black mask superimposed on the Agouti pattern would obscure the underlying color, as the black would dominate the fawn. An extensive mask covers the entire face and beyond, whereas a limited mask allows significant fawn coloration to show through on the muzzle, provided the dog has a small black saddle. I wanted to highlight that some dogs appear entirely black but, upon closer inspection, they are not, they possess only a tiny amount of fawn on the hocks, coloration that may only emerge as the dog ages and the coat lightens (since they are born black and the black recedes over time). Furthermore, some dogs have such an extensive black mask that it extends onto their limbs, as seen in the Belgian Malinois used earlier as an example of the A^y allele, or in very dark working-line German Shepherds. Although they are technically black-and-tan, these dogs often have black (or nearly black) feet where fawn would normally be expected. Consequently, while some dogs appear solid black, they are genetically black-and-tan with nearly invisible tan markings, naturally, their offspring will also be black-and-tan, easily solving the mystery in such cases. Below is an example of a dog of this type.

In the pictured above we see a black-and-tan working German Shepherd, so dark that he appears solid black, however, upon zooming in, you can see actual tan fur around the hocks. Genetically, this dog is not solid black but black-and-tan, consequently, it is normal for him to produce black-and-tan offspring. Since the extent of the black and tan areas can vary, and the distribution in the offspring depends on the other parent’s genome. But this dog is NOT solid black!

dark working line black and tan german shepherd A^tA^t

black and tan german shepherd with small saddle A^sA^s

As for A^w dogs, the gray ones, the only difference lies in the non-tan hairs: in A^s A^t dogs, hairs are all fawn or all solid black, whereas in A^w dogs, in the dark parts they are “banded” (or “agouti“), meaning they feature alternating bands of black and tan, essentially, as the hair shaft forms and emerges from the follicle, it alternates between black and tan segments. In short, an A^w dog has banded hairs where an A^s or A^t dog has black ones. Consequently, it is difficult to confuse a dark gray-and-tan dog (like the one shown below) with a solid black dog,a mistake that “can” happen with the very dark black-and-tan dogs mentioned earlier. However, the same principles regarding pigment extension and modifiers apply to gray dogs, and some grays are so dark they appear almost black. Note the dog further down, a show-line gray-and-tan, which displays a pigment extension pattern similar to the show-line A^s dog shown earlier, in contrast, working-line dogs, much like working-line black-and-tans,are generally much darker. The dog immediately below is an example of this; returning to the topic of the extended mask, it also has black feet. While not definitively proven, this likely results from specific modifiers: show lines favor tan legs, so breeders have selected for modifiers that create a “saddle” pattern even in gray dogs.

VERY DARK Working Line Grey Wold German Shepherd

Show Line grey wolf german shepherd

However, regarding the two Black-and-Tan variants, A^s is incompletely dominant over A^t, and they code for a similar phenotype. It would be too time-consuming to predict every combination by treating them separately, there are already so many possibilities. Since they behave identically, both being dominant to recessive black but subordinate to wolf-grey, we can calculate the potential offspring combinations by pairing two dogs chosen from the three possible German Shepherd colors (grey, black-and-tan, and black). We will visualize the Punnett squares for each possible mating, accounting not only for the dog’s visible color but also for any alleles masked by the dominant one, alleles that can still be passed on to the puppies. Finally, we will briefly explain how the black-and-tan phenotype manifests depending on whether A^s or A^t (or both) is present in the genotype.

For the sake of this explanation, let us assume there is a single “black-and-tan” allele, which we will call A^st, and later we will detail how the dog’s coat is affected depending on whether A^s, At, or a combination of both is present. And there is more…

By taking two parents, each representing one of the possible combinations, and temporarily treating A^s and A^t as a single A^st  allele, we can calculate the theoretical outcomes of the mating.

Possible Agouti alleles couples are (A^w–A^w), (A^w–As^t), (A^w-a), (A^st–A^st), (A^st-a), (a-a)

• (A^w–A^w) (A^w–A^w) – 100% (A^w–A^w) Homozygous Grey
• (A^w–A^w)(A^w–A^st) – 50% (A^w–A^w) Homozygous Grey-50% (A^w–A^st) Greycarrying Black and Tan
• (A^w–A^w)(A^w-a) – 50% (A^w–A^w) Homozygous Grey- 50% (A^w -a) Greycarrying carrying recessive solid black
• (A^w–A^w)(A^st–A^st) – 100% (A^w–A^st) Greycarrying Black and Tan
• (A^w–A^w)(A^st-a) – 50% (A^w-At) Greycarrying Black and Tan – 50% (A^w-a) Greycarrying recessive solid black
• (A^w–A^w) (a-a) – 100% (A^w-a) Greycarrying recessive solid black
• (A^w–A^st)(A^w–A^st) – 25% (A^w–A^w) Homozygous Grey-25% (A^st–A^st) Black and Tan Homozygous – 50% (A^w–A^st) Greycarrying Black and Tan
• (A^w–A^st)(A^w-a)-25% (A^w–A^w) Homozygous Grey25% (A^w–A^st) Greycarrying Black and Tan – 25% (A^w-a) Grey carrying recessive solid black – 25% At a Black and Tan carrying recessive solid black
• (A^w–A^st)(A^st–A^st)-50% (A^w–A^st) Greycarrying Black and Tan – 50% (A^st–A^st) Homozygous Black and Tan
• (A^w–A^st)(A^st-a) – 25% (A^w–A^st) Greycarrying Black and Tan – 25% (A^w-a) Greycarrying recessive solid black 25% (A^st–A^st) Homozygous Black and Tan 25% (A^st-a) Black and Tan carrying recessive solid black
• (A^w–A^st)(a-a) – 50% (A^w-a) Greycarrying recessive solid black – 50% (A^st-a) Black and Tan carrying recessive solid black
• (A^w-a)(A^w-a) – 50% (A^w-a) Greycarrying recessive solid black 25% – (A^w–A^w) GreyHomozygous – 25% (a-a) Homozygous recessive solid black
• (A^w-a)(A^st–A^st) – 50% (A^w–A^st) Greycarrying Black and Tan – 50% (A^st-a) Black and Tan carrying recessive solid black
• (A^w-a)(A^st-a) – 25% (A^w–A^st) Greycarrying Black and Tan 25% (A^w-a) Greycarrying recessive solid black 25% (At-a) Black and Tan carrying recessive solid black 25% (a-a) Homozygous recessive solid black
• (A^w–a)(a-a) – 50% (A^w-a) Greycarrying recessive solid black 50% (a-a) Homozygous recessive solid black
• (A^st–A^st)(A^st–A^st) – 100% (A^st–A^st) Homozygous Black and Tan
• (A^st–A^st)(A^st-a) – 50% (A^st–A^st) Homozygous Black and Tan – 50% (A^st-a) Black and Tan carrying recessive solid black
• (A^st–A^st)(a-a) – 100% (A^st–a) Black and Tan carrying recessive solid black
• (A^st-a)(A^st–a) – 50% (A^st–a) Black and Tan carrying recessive solid black – 25% (A^st–A^st) Homozygous Black and Tan – 25% (a-a) Homozygous recessive solid black
• (A^st–a)(a–a) – 50% (A^st–a) Black and Tan carrying recessive solid black 50% (a–a) – Homozygous recessive solid black

Now the reasoning, the famous “table” we see above,becomes quite clear: a black dog in the agouti series must possess two copies of the a allele; consequently, it can only pass one a allele to its offspring. Therefore, the offspring of two such black dogs will inevitably also possess two a alleles in the agouti series, given that the parents cannot pass on anything else. Indeed, if any other gene from the agouti series were passed on and paired with a, that other gene would prevail, this is precisely where we begin to unravel the mystery.

Yes, non-black dogs born to two black parents are non-black because, in reality, the agouti series of at least one parent does not contain two a alleles, it contains only one, or perhaps none at all. But then, why do the parents appear black? Why didn’t they pass the a  allele to their offspring?

The reason is that this specific type of black known as recessive black (a ) exists almost exclusively in the German Shepherd. While it has reportedly been found sporadically in Belgian Shepherds or Shetland Sheepdogs, black coloration in other breeds generally stems from a different genetic series, which we will examine shortly, known as dominant black. Clearly, the naked eye cannot distinguish between these two types of black,only a DNA test, easily performed today, can reveal the difference. The fact remains that recessive black is typically found only in German Shepherds, whereas other breeds possess dominant black, which is caused by a gene located in a different genetic series.

A gene like dominant black is described as “epistatic” because, when present, it prevents genes from other series from manifesting their effects on the phenotype (the dog’s physical appearance), even though those genes remain present in the genotype (the dog’s DNA) and can still be passed on to offspring. This is yet another piece of the puzzle falling into place, another part of the mystery being unraveled in this article.

The other type of black, the dominant, is found not only in the Belgian Shepherd (Groenendael) but also in the Black Labrador and the black-and-white Border Collie (where the white areas result from a lack of pigment caused by other genes irrelevant to our current discussion, though genetically the dog is just as black as the Labrador). It is also found in the Weimaraner, which appears lilac due to two other genes from different genetic series acting in a homozygous state (as recessives), these alter the black’s intensity, and thus the shade perceived by the eye by combining the “dilute” effect (turning black to blue) with the “liver” effect (turning black to brown), even though the dog remains genetically black, just like the Labrador. I could go on for hours, because black in dogs is generally produced by this other dominant gene we are about to explain. a gene that, however, “should not” be present in the German Shepherd, yet, as you will see has somehow found its way in, causing the “mess” we are trying to explain in this article.

The locus in question is the K locus, which has three alleles.

–K (k uppercase) is the most dominant allele, if just one of the two genes (inherited from the mother or father) is K, the dog will be solid black, barring the influence of other genes that alter appearance (such as the ones we just mentioned, while others exist, they do not concern us right now, and in any case, only a few usually undesirable ones are occasionally found in German Shepherds).

–Kbr (brindle) is recessive to K but dominant over the next allele, lowercase k. If present in a homozygous state (Kbr inherited from both parents) or paired with lowercase k, it essentially makes the dog appear as if viewed through a black grid. Naturally, this effect is only visible on non-black areas. consequently, brindle dogs display fawn sections streaked with vertical black lines. One sees the colors determined by the genes in the previously discussed agouti series, but with the fawn areas showing the brindle pattern—as if viewed behind a grid. Brindle German Shepherds did exist in the early days of the breed, but because the gene is dominant, it was quickly eliminated from the breeding pool. Eliminating a dominant gene is much easier than eliminating a recessive one, as the latter can remain hidden for generations. However, modern genetic testing allows us to identify carriers and simply avoid breeding them, or at least avoid mating them with other carriers, thereby preventing the emergence of undesirable traits present in the breed’s genome without sacrificing genetic diversity (which would happen if we stopped breeding all carriers).

–k (k lowercase) is the only allele that should be present at the K locus in German Shepherds,  if the dog possesses two copies of k, the effect of the agouti series will be visible.

Beowulf,one of the founders of GSD Breed,it is clearly visible that he was brindle.

Now, a black German Shepherd, not just mostly black with a few tan markings, mind you, but solid black, should be “aakk“. Mating two “aakk” dogs together produces only “aakk” offspring, it’s a mathematical certainty (barring any sudden genetic mutations), and that is what we used to believe about German Shepherds until recently.

So, what is happening now?

It turns out there are some German Shepherds that carry a capital “K” instead of a lowercase “k” in the K series. This creates a complication because the capital “K” masks everything else, making the dog appear black regardless of its underlying genetics.
A German Shepherd with one (or even two) uppercase “K” alleles can carry any of the three possible alleles in the Agouti serie,A^w, A^s, A^t or a in various combinations (heterozygous pairs or homozygous).
Now, if we mate a “dominant black” dog,which, for the moment, usually carries only one uppercase K dominant black, with a true recessive black dog, there is a 50% chance that the “fake” black (the dominant black) will pass the  dominant black gene to the offspring, and a 50% chance it will pass the lowercase k letting agouti series to be visible.

Right, but in addition to passing on one of the two K series genes, it will inevitably pass on one of the two genes it carries in the Agouti series as well. Let us consider the case where the “dominant black” parent passes on the lowercase k allele, since otherwise, the offspring would obviously always be black regardless. It goes without saying that if the dominant black parent were also genetically black at the Agouti locus (i.e., carrying the recessive black a allele), there would be no surprises, indeed, some dogs possess both dominant black K and recessive black a. However, if the parent carries A^s (saddle tan),  A^t (black and tan), or A^w (wolf-grey) at the Agouti locus, and passes one of these to the offspring, the resulting color will be determined by the allele passed on by this “false black” parent (which is dominant over “true black“). While they could pass on recessive black a, they might also pass on wolf-grey or black-and-tan, depending on the specific alleles present at the Agouti (A) locus of the “dominant black” parent, given that the other parent, a “true black” , will pass on only the lowercase k and a alleles.

Things get even more complicated if both parents carry the dominant black gene, however, by using a Punnett square for the two series, we can determine the possible outcomes of a mating. Furthermore, both series can now be tested via DNA analysis at many genetic laboratories.

In short, if you have any doubts, test the A-locus and K-locus of a black dog, then follow the charts provided above for the Agouti series and below for the K-series.

For a dog that is “not black” assuming I have explained this clearly and you have understood the article, you will know that a K-locus test is unnecessary, as the dog will certainly possess two lowercase ‘k’ alleles. Therefore, unless you wish to determine whether a grey dog ​​carries recessive black and/or black-and-tan (in which case you would test the Agouti series), no testing is required for a non-black dog.

Once the K-series has been tested in a black dog, you will know whether or not you can refer to the color charts provided earlier.

Breeding results in cases where the K (uppercase) gene is present in one or both parents.

Father Dominant Black Agouti Carrier, Mother Agouti

Both Parents Dominant Black, Agouti Carrier

Father Dominant Black Homozygous, Mother Agouti

Father Dominant Black Homozygous, Mother Dominant Black Agouti Carrier

Now, if I have explained the two genetic series well, you will also grasp how it works in the Belgian Shepherd.

The Groenendael, being solid black, will have one or two uppercase Ks in the K series. Groenendaels and Tervuerens can be bred together, the Tervueren has only two lowercase ks in the K series, so it necessarily reveals the Agouti series, specifically A^y/Ay^s(fawn/sable). If the Groenendael has two uppercase Ks, its offspring will invariably be black; however, if it has only one, breeding it with a Tervueren (or a similarly constituted Groenendael) can produce both Groenendaels and Tervuerens.

In the Belgian Shepherd’s Agouti series, we generally see only A^y/Ay^s (fawn/sable), which is the most dominant allele in that series. Of course, there are exceptions where dogs carry other alleles (“A^w“, “As“, “A^t“, or “a“); for these to appear in the phenotype, two carriers must mate and both pass on the non-“A^y/A^ys” gene to their offspring combined, naturally, with two lowercase ks in the K series. And I assure you, this does happen from time to time.