White Swiss Shepherd’s Coat Colour Genetics Explained. WSS is not congenitally Deaf

White Swiss Shepherd is not deaf!
White Swiss Shepherd’s Coat Colour Genetics Explained.

Congenital Deafness in Extreme White Dogs.

White Swiss Shepherd could not be affected by white coat congenital deafness, simply because, even if it’s called white, it’s not a real white dog!

It seems to be a pun, but it’s real, even if in the name of the breed we find the word “white”, White Swiss Shepherd it’s fawn, but it’s so clear, there is so little “drops of colour” in the fur, that our eyes sense them as white. But, as they are very few, they are present, it’s not a real white like in “white spotting” patches in other breeds, where we have total absence of melanin, there is a very few but we have it! And even in real white subjects, if we look them on snow, it’s obvious they are nor really white as they seems to be yellow. Genetically, White Swiss shepherd coat is the same coat of Labrador and Golden retriever, which has more colour drops on furs, or like dogs with the same clear white coat like Samoyed, Maremma Sheepdog, Volpino Italiano and so on.

Let’s now to explain the coat colour genetics of White Swiss Shepherd as simply as possible.

As dogs in the word, of different breeds and mixes, seems to have a lot of different colours on furs, they have only 3 pigment type, or better two real colour and one “non colour”, Black pigment called Eumelanin, and red pigment called Pheomelanin. We have also the third “non colour”, a real clear white from total absence of both type of melanin in the coat, or on the skin, eyes, nose and so on, by the way, where we see a pink colour in the dog, it’s caused from blood courses under skin or other tissues because the lack of melanin let us glimpse running blood under tissues. White patches, where pigment it’s completely missing, covers from a little spot to a big area until the entire body in dogs, and they are real white patches, caused from genes some of which have been sequenced yet, some of which are still under study and not discovered at all, but only assumed as possible.

The black and red pigment on the coat of the dog may change a lot their appearance, as there are a lot of modifier genes, so all these different shades of black and red in some divided areas/furs or both in the same fur divided in colour bands, mixed with real white zones, spread in different way through dog’s coats, make them look all so different one to each other, especially from one breed to another. Well, in dogs, we have pheomelanin only in coat, all over other pars of the body is coloured only by eumelanin, we are speaking about skin, nose, nails, mucosal, iris, blood vessel, by the way, other parts of dog’s body where we find melanocites, they are only producing eumelanin and fawn colour may be found only on coat.

Let’s talk about some of the more series controlling coat colour in dogs, those series are too much to explain all here, and we don’t need to do it to talk about this argument and we will see only 3 series.

First series is the E series, the so called “Eumelaninic Mask” series, in which we have 5 possible alleles. 2 of them are typical only in Cocker Spaniel (Eh allele or harlequin) the other is found in Saluki and similar dogs (Eg from Grizzle), so it’s not the case to write more about it.

The other alleles we find usually spread about all breeds are:

“Em” from “Eumelaninic Mask”, the most dominant allele of the series, the one which cause a black muzzle to be present in the head of the dog. By the way it’s obvious we can’t distinguish the effect on a total black dog, but it doesn’t matter, a total black dog with the Em allele, may pass it to offspring and a non total black son will show black muzzle. In some dogs like Belgian Malinois we have a so extended black muzzle than it expands also in the front side of chest, neck,and legs too, in front and sometimes also in back legs. There must be other modifiers gene causing this. At the moment no one found it.

“E” is the half way dominant allele, it causes the dog to let Agouti series colour express on dog without black muzzle. Agouti in a few words is the series where “is written” in which body parts of the dog we can find fawn or black furs, but there are other loci influencing dog coat colour, we don’t need to explain all about this loci now, but in some cases, some alleles in some position can cause an effect called “epixtasis”, a phenomenon in which an effect for an allele combination in a series covers others series alleles effects, and the Agouti series alleles effect on the dog may be covered from other series genes, one of those effects is the one which forces a dog to be total black, and, as obvious, in this case we are not able to see where fur must genetically be black or red, even if in DNA we have those genes the same, and they may be passed to offspring. So, again, in a total black dog, we are not able to see if we are on a case of Em allele or E allele, because of the effect is hidden by a total black coat, even if the dog can pass this allele to his offspring.

“e” or recessive fawn, is the allele we are really interested of, the one we find homozygously in our breed, or in other recessive fawn breed listed before, like many other.

Homozygous recessive fawn causes an epistaxis effect too, and in this case, all fur on coat are forced to be fawn, or better, the production of eumelanin is inhibited in coat, and only in coat, so all fur will be fawn, and in the rest of the body we have the same colour as in the case of a not Homozygous recessive fawn. If the nose had to be black it will be black again, if the nose had to be brown (black turning brown is an effect caused by other gene), then the nose will be brown again even with Homozygous recessive fawn. This epixtasis hides the effect of alleles on the other series in the phenotype, so it’s not possible to be sure of what alleles we have on a subject without testing DNA, and today it’s possible to test a lot of coat colour series as a lot of those series have been sequenced. By the way if we cross-breed a recessive fawn dog with a not recessive fawn dog, if the not fawn dog it’s not carrier of recessive fawn gene, we will get only not recessive fawn dogs, and the colour of this pups depends on other series no more hidden by Em series effect. If the other dog has one or two “Em” allele on “Em” series, we will have a black muzzled dog because “Em” it’s dominant over “e”, which will be surely present on the offspring as one parent is Homozygously recessive fawn “ee”, and can pass only”e” to offspring.

Theoretically if we cross breed a White Swiss Shepherd with a “classic coloured” German Shepherd dog, as the breed is almost the same, we will get only German Sheperds coloured like pups, but i write theoretically, because as “ee” hides almost all other genetic series alleles in the dog, we are not sure no one used other breed, mixed in White Swiss Shepherd. For example, we have some subjects positive to DNA Merle Allele, and as it’s not a possible allele we can find in German Shepherd, and as the two breed were divided during second world war, when surely Brindle an Merle genes, as they are dominant and simple to remove from breeding, where no more present yet, it sounds very strange to me to find a Merle gene on a White Swiss Shepherd! But that’s is, some White Swiss Shepherd are positive for Merle gene testing, and i am very curios to know from which breeds it comes!

Turning back to White Swiss Shepherd coat colour series, we may talk about another gene, but for the moment it’s only assumed, and it’s called I for Intensity. It seems it regulate the quantity of “ink” in the fur, so if we look to a more rapresentative breed such as golden retriever, we can find a lot of shades of red, from almost white like in White Swiss Shepherd, to a deep red similar to Irish Setter colour. And it seems the effect of the gene it’s quantitative not qualitative, it means, if we have a very dark red parent and a less dark parent, and we mate them together, we will obtain pups with colour tone between the clearer and the darker of the parents and with a tendency to an half way.

scalagoldenIn the upper picture an example of the different red tones a golden retriever may assume.

We have more than one series influencing colours tone in the dog colour genetic, some influences only red colour, some only black colour, some both, and some only in some body region, I gene seems to influence only Pheomelanin quantity on the coat of the dog. Classic German shepherds too may have a darker or lighter fawn tone, usually show dogs are reddish, we can say like a deer, some working dog may be almost white in tan parts as they must work and not win an expo, and no one takes cares of this detail.

Huskies are an example of a looking like white tan coat, so they seems to be white in fawn parts, and their real white spotting, we can say similar to border collie white spotting, covering muzzle chest, end of tail and lower part of legs, are indistinguishable from fawn parts, as they are very very pale.

Well, one of the dogs domestication process side effects is the presence of real white patches, caused by total absence of colour in some parts of body and coat, patches which are not present in wild animals. As the argument it’s long and complicated, we will not explain it now at all, but we can summarize in a few word writing only some simple concepts. In the domestication process of wild fauna, men decided which mate had to be done, so usually wild animals are not very happy to live with us, to be manipulated and so on, they are scared, they try to escape from us, they can also be aggressive for fear, so men started to mate together more quiet and manageable livestocks, we all know pups on any species are more confident, more curious, and more manageable, so adult subjects who were a little more confident with us, we can say they were more near to a puppy stage. Now, this situation involves all endocrine system, as well as nervous system, but as nervous system is strictly related with coat and coat colour in embryo, a sort of delay in the growth of the subject, was related with a delay in the migration of melanoblast, which are melanocites precursors cells, and which migrate from neural crest (we can say backbone) to the part of the respective body in which they have to “work” once the pup is born. But if the delay of the migration it’s too high, melanoblasts will dead before they arrive in their location, and the part in which they had to arrive will lack of melanocites, causing total absence of pigment in those parts.

In the upper picture we can see the process of melanoblasts migration in a rat embryo.


In the upper animated gif we see the effect of this delay, as more as we have delay as more white patches expandes. The first parts loosing colour will obviously be more far from backbone, so paws, end of tail, muzzle, chest and belly, and then colour will retire until all body is covered of “white patches”, the last parts where colour will remain are the more innervated parts, backbone line, around tail insertion, ears, around eyes, with this order. For this reason usually also total white dogs like Dogo Argentino born with a little black patch in this position.

Really white dogs can suffer of white coats deafness for a lack of melanin, they really may suffer of deafness caused by extreme white coat.

So, why extreme white coated dogs may be deaf?

Well, it seems if there is no pigment in blood vessel irrorating cochlea, the circulation doesn’t function in the correct way, so nervous cells of the cochlea die and the cochlea will not properly function anymore. Those dogs doesn’t born deaf yet, they become deaf in the first days after birth, but as they born whit auditive cones closed, and begin to ear at about 3 weeks old after those cones opens, we can say they will be deaf from birth.

This is the reason why in extreme white patched dog breeds we have a high percentage of mono or bi-lateral deaf dogs. Usually, if the ear is coloured at least also only with a small coloured patch, it will properly function. This it’s not sure, because we need blood vassels to have pigment above, and it’s not obvious even if we have melanin outside in the auricle, but it’s more likely there is pigment on blood vassels if the auricle it’s not completely white.

Which genetic series are involved in white spotting? We have for sure a genetic series called S from Spotting. And for sure 2 alleles have been sequenced:
“S” no white spotting and
“Sp” for piebald spotting.

Sp it’s the kind of white patches typical of Amstaff, Jack-Parson Russel Terrier,English Setter and so on.

There is another candidate gene for another kind of white spotting, we assume is Si, even if maybe it seems to be in another series rather than S and Sp series, and this because it seems we have a sum of effect of both type of mutation in some dogs.

Si (i stands for Irish) is the typical spotting of Collie: Border Collie, Shetland Sheepdog, Welsh Collie, Australian Shepherd. When present in homozygousis, this mutation cause white patches on end of tail, lower parts of the legs, muzzle, collar and belly, the typical border collie white spotting we all well know! Standard border collies may have homousygous Si, but If only a copy of the gene is present in a dog, we have only a few white patches usually in the finger / the paws, in the chest and sometimes a small in the muzzle only near mouth and not the classical white border collie mask. This is the same white spotting sometimes occurs in dogs without white spotting mutation, which it’s called residual white and which is caused by a little delay in the development of the embryo.

Si isa recessive gene, and a little white spotting like the one wrote beforre may be a indication of single dose Si on a dog.

Well, in some breeds such as border collie we must not have piebald gene Sp, but some dogs has it the same, and the effect of Sp mixed with Si in double dose, will cause dogs with too much white patches. If Sp is in single dose, we can see broken patches where usually they have a uniform dividing line, if we have homozygous Sp then white will be too much, and they may be extreme white like a Parson-Jack Russel terrier for example.
Border Collie standard wants white patches to cover less then 50% of the body, so usually those dogs are not following breed’s standard.

Single dose piebald in dogs with no Irish spotting gene causes often a irish spotting like effect, for example again in amstaff, we all remeber irish-like spotting dogs.

Double dose Sp will make dog to be almost or total white, but not in all cases and breeds ,so maybe there are other genes involved, but surely we need homozygous Sp.

Turning back do deafness, it seems only piebald gene (Sp) is involved as it’s the cause of can cause an extreme white coat.

If we speak about our breed, White Swiss Shepherd, we wrote yet it’s not a real white coated dog, it’s a very clear fawn, and the mutation forces all the coat to be fawn, and in this breed, colour in the coat it’s very few and we can speak of optical white, but not a really genetically White.

In the upper picture, one of my bitches, as you can see in the snow she seems to be yellow when usually she’s almost clear white to our eyes.

By the way, the mutation involves only coat, in the rest of the body, melanin are unchanged, even inside ears, so yes, White Swiss Shepherd may be deaf, as any other dog in the word, for infections, traumas, otite or other congenital problems, but not for extreme white coat, and the percentage are really different, in extreme white spotting breeds percentage of deafness it’s very higher rather in well pigmented skin dogs. White Swiss Shepherd may have well pigmented nose, mucosal and eyes, some of them has also black nails and skin, but even not much pigmented subjects has not a lack of melanin inside ears, there is a few, but we have some not very much mucosal and skin pigmented dog, so even those dogs can’t be deaf for extreme white spotting because of pigment it’s not really totally absent.

We spoke about Merle gene in our breed, and the chance of some White Swiss Shepherd to have this mutation in the DNA. As Merle mutations involves only eumelanin, a recessive fawn dog will hardly show the presence of this gene, we may have a lack of pigment on mucosal, or blu eyes, but we may ignore it’s for merle gene, as sometimes appends the same, we know what append if we mate together two merle dogs, and we can do that as we don’t know they carry this gene, in this case we have 25% of chance to have a double merle dog, and we all know which problem may have double merle dogs: tghwy usually are deaf or almost deaf (for the same reason of too much white in the ears), blind or almost blind and sometimes with deformal pupils or eyeballs, because as we told in the beginnig of the article, pigment is strictly connected with nervous system.

So, in conclusion, does have sense to do BAER test to White Swiss Shepherd?

The answer is neither yes or not. If we have enough money, the more test i made the more i am sure of perfect health of my dogs, but, if in a line we have not noticed about ear problems, BAER test it’s a surplus. As i told before, any dog in the world may be deaf, and not only for extreme white coat but for other reason too, but as any dog in the world may have a lot of illness we can’t test for hundred problems, we do tests only for a spread and known problem of our breed, and deafness it’s not a White Swiss Shepherd known spread problem!

If you want to read more about congenital deafness