If you talk about German Shepherd, people imagine a classical black and tan "saddled" dog,

usually a "show type" one, because of it is the most common German Shepherd dog colour and type,

but we know it's not the only possible colour in our breed.

If we walk around with a total black or a sable German Shepherd dog, people often ask if it's a

mix breed dog, or, for example, they think it's another breed, such as Groenendael Belgian

Shepherd Dog for total black dogs. But German Shepherd lovers knows there are 3 different accepted colours in German Shepherd dog genetic.

Or, we better say there are 3 different colours, but with modifier genes, not all sequenced yet,

that can change a lot the final "layout" of the dog itself.

 

Before we speak about the genetic colour transmission of German Shepherd dog , we must write a little introduction about genetic, for better understand the rest of the article

 

All the "informations" regarding a living creature it's written in "DNA", a sort of “double chain”

with a lot of “couples of genes”, all these couples contains informations about all the "details"

of the subject, and the 2 genes in a couple are redundant , one is passed from mother and one

from father and both describes a single physical characteristics about the subject. Dogs has 78

(39 couples of) chromosomes and each chromosome contains a certain number of genes, each gene,

or set of more than one genes, describe a characteristic about the subject, and this comprehends

also character, behaviour, growth rhythm and so on.

 

The "values" a gene can assume are called "alleles", usually we ave from 2 to 5 possible

different alleles for a gene , but it's not impossible we have more than 5 or sometimes only one

possible allele.

 

A gene and it's possible alleles are called "series"

 

the position of a gene into the DNA chain it's called "locus" (singular), "loci" (plural)

 

What we will see "outside" looking or doing Clinical examinations to a subject it's called

"phenotype", what we have "written inside" DNA it's called "genotype".

 

phenotype it's always a combination of dominance rules between genes (alleles) and what append

to the subject in the place he grows and lives during ontogeny.

 

so, if we look to the subject from outside, it's not always so easy to understand which values we

have in a couple of genes . We must do a genetic DNA TEST, when possible to know it for sure, and we say when it's possible because of not all genes have been identified and studied yet.

 

We know there are dominance rules between alleles.

 

If both alleles in a series are identical, we speak about "Homozygous", and there is no doubt

about phenotype, we see what both identical genes in the series describes.

 

But, if genes are not identical, when we have 2 different alleles in the couple, we speak about

"Heterozygous", so, in these case, we have "dominance rules" between different alleles, and 

what we see outside in the phenotype is determined by those rules.

 

We have several dominance rules type, we explain the more interesting for this article.

if the "dominance" of one allele against the recessive one it's "complete" only the dominant one

of these alleles is expressed, so the subject looks like  alleles are both of the dominant value

in the DNA,

 

when dominance it's "incomplete" the phenotype is an intermediate type between the

two homozygous phenotypes,

 

if we have "co-dominance" both phenotypes are full expressed like in the separated homozygous cases (like blood type, that can be A, B or AB).

 

Dominant alleles are generally written with a capital letter, for example B. Recessive alleles

are written with a lower case letter, for example b.

 

if we have more than two possible alleles for a series, we have a sort of chart, from more

dominant to less dominant values. We can write... A1>A2>A3...>an where A1 it's the more dominant allele and an the less dominant. If we take 2 allele from this series, the left one value in the chart it's dominating all values on his right.

 

Well, it's time to speak about some genetic series yet sequenced and with a suitable test,

useful to clearly identify genotype, because, as we told before, it's not always possible to

know genotype by only looking to dog's parents/sons and dog's phenotype.

 

The K Series:

Dominant black it's very common in a lot of breeds, like for ex Groenendael Belgian Shepherd Dog,

Labrador Retriever, black and white Border Collies and so on, but not in German Shepherd dog, where we have a recessive version of solid black, caused by another series, called Agouti series. Agouti is the main series we have to look at, to understand transmission of colour in our breed.

 

Dominant black, by the way, is caused by K series, where we have 3 alleles:

K (upper case) the top dominant, we only need one allele in the couple with K value to get solid

black dogs

Kbr, for Brindle, we need 2 Kbr or a Kbr and a k (lower case) to get brindled dogs

 

k  (lower case) it's the less dominant allele, and we need 2 k alleles in the couple to see the

effect of the Agouti series upon our dog.

 

Kbr too let us see Agouti series effect, but with a sort of "black grid" upon the dog, so where the dog

is black we obviously see no effects, where the dog it's fawn, wee see a striped fawn zone...

Brindled boxer it's a typical example of total dominant fawn dog but with a grid upon it than

let us see black striped fawn zone, and in boxer the fawn zone it's "all the dog", so the dog

it's all brindled.

 

In German Shepherd dog, we ALWAYS  have (k-k), the less dominant allele in Homozygous form, even if it seem there are some subjects with one or two K (upper case) in the K series (dominant black) but it's not the more common form of solid black for German Shepherd.

 

In Belgian Shepherd dogs, for example, we have (K-K) or (K-k) in Groenendael, and kk in fawn dogs such as Malinois, Tervueren and Leknois.

 

The Agouti series:

let's now got to explain Agouti series and his 4 allele.

 

The more dominant allele it's aʸ  , where a  stands for Agouti and ʸ   for yellow

 

aʸ  – Dominant Fawn

This it's the dominant fawn allele, we need at least one allele with this value in the Agouti series,

to get dogs looking like fawn Great Dane, fawn Pug or Tervueren and so on. This allele it's not animore present in German Shepherd, because of it is very easy to eliminate a not wanted allele from a series when it's the dominant one, we only need to not reproduce fawn dogs and we will loose the aʸ   allele in the breed forever. By the way, a recessive allele can be hidden for generations and generations so we can get recessive colours on pups after a lot of generations when, for a case, two alleles of this type combine together.

 

So, now we can understand why, usually mix-breed dogs born total black or fawn, because those are

the two most dominant colours. Solid black from K series, or fawn in Agouti series in case K series

has kk alleles couple.

 

aʷ-Sable

the second allele in order of dominance, after Ay is Aw, where w stands from wild. It's the grey, or

sable one, the most common colour for working German Shepherd Dogs. It's the colour of the wolf, with some modifiers genes, but it's the same colour, and this allele is present in a lot of wild animals

because of it's the most mimetic colour in a forest.

 

aᵗ -Tan points

After aʷ, we have aᵗ , with t standing for tan points, it's the classic black and tan saddled German

Shepherd Dog. Even if it seems we have different types of black and tan, from "Dobermann-like"

black and tan to an almost all fawn black and tan dog, in the Agouti series it's always an aᵗ aᵗ  

or aᵗa (a it's the recessive black, we will soon look to). We will back to this allele after, to better

explain it.

 

And at last we have our recessive black allele:

a -recessive solid black

We need two a allele to have recessive solid black German Shepherd... and the phenotype it's not

different from K dominant black one, so only with a DNA test we can understand and be sure if a

total black dog it's black for a K gene in the k series or an aa couple in the Agouti series with (k-k) in the K series.

And it can be both, (K-K) aa or (K-k) aa ,but with a upper case K in the k series total black it's caused by K even if the dog can pass recessive black to his pups.

 

(K-k)dog can generate all possible colours, if we breed two (K-k) black dogs, (k-k) aa dogs can only generate (k-k) aa black dogs if we breed two (k-k) aa black dogs.

 

Let's now turn back to the most German Shepherd's colour, Black and tan saddled.

Until Agouti series have not been full sequenced, the saddled allele it was supposed to be

distinct from the black and tan “dobermann-like” one. Now we know it's not so. There are only one

black and tan allele in the Agouti series and other modifier genes, not all sequenced yet, deciding how much tan expandes from when the dog born.

As we all have seen German Shepherd Dog pups, we know they all born almost black with little tan

points, upon eyes, at the side of the muzzle, on the back of tail and on paws/lower side of legs... and while the dogs grows up, those points expand and it remains only a black saddle and a black, muzzle or sometimes a little stripe on the backbone.

If we cross an almost black dog with a clear dog, with only a little black stripe on the backbone, we got pups with an intermediate saddle, varying from most saddled to less saddle between parents range, with tendencies to a middle saddle extension.

 

Even fawn colour are always genetically the same fawn, even if it seems it can be so different between subjects, fawn is varying from almost white or white looking (because of the too few pigment ion the hair) to a strong red.

Fawn colour it's caused by Pheomelanin, the red pigment, and Eumelanin causes the black pigment in the hairs.

But we have other modifier genes, that can affect those two pigments on the hair of the dog, and in the case of black and tan, we can consider the I gene, where I stands for intensity and it affects fawn only, clearer fawn has less pigment and vice versa, and it's decided by the allele in the I loci. Unfortunately I has not been sequenced yet.

 

By the way, even in total fawn dogs (like Belgian Shepherds) or sable dogs, I allele affects

fawn intensity. So it doesn't matter what we found in Agouti allele, we will have clearer or

more reddish fawn in dogs depending on I gene.

 

once time even dominant black allele, was supposed to be an Agouti allele, then after

discovering K series and sequencing all Agouti series Alleles, geneticists realized it was not so, and

dominant black has another loci. The K loci.

We do not have a dominant black allele in Agouti series!

 

 

Well, if we want to forecast possible pups colour out of a litter, we must consider only

parent's Agouti alleles, then  fawn intensity and extension will probably be a intermediate between

parents values like wrote before.

 

Let's now see wich agouti alleles combinations are possible in German Shepherd dogs