White Coat Color in Dogs

This webpage is part of a series on Dog Coat Color Genetics and was last updated on March 19, 2016 by Sheila Schmutz


White is often called the absence of pigment. Comb out a few hairs from your dog and lay them on a white sheet of paper and try to decide if you see any hint of pigment in the hairs. If you see a hint of red pigment, then your dog is probably better described as cream. Cream Dilution is also discussed on a separate page in this series about dilutions.


Albinism

Tyrosinase is one gene that causes some forms of albinisim in mice and people and cows. Most researchers have equated the C locus with tyrosinase because of albino mutations in this locus. Animals with mutations in tyrosinase can also be white or white haired with colored points, like the Siamese cat, according to Searle (1968) and O'Brien (1986) and Lyons (2005). Little discussed albinism in dogs as caused by a genotype of caca at the C locus, but that this condition was probably rare. Our lab has sequenced the cDNA for TYR from several dogs, including some albino dogs and did not find any polymorphisms. This does not rule out the possibility of a mutation in the promoter, but it does suggest that this gene is not likely to be the C locus in dogs.

Tyrosinase (TYR) has been mapped to dog chromosome 21 by our lab.

SLC45A2 is another gene involved in albinism in humans. It appears that this gene is the best fit for the C locus in dogs, described by Little.

Some people call white Dobermans "albino". This coloration is inherited in a recessive manner, as is classic albinism, often called oculocutaneous albinism because it affects both the eye color and the skin/hair color. We had studied the DNA sequence of tyrosinase in such dogs, (and blue and Isabella Dobermans), and found no mutation in the coding sequence of this gene.

Paige Winkler studied the SLC45A2 gene in white Dobermans during her PhD at Michigan State University, in the labs of Dr. Simon Petersen-Jones and Dr. Patrick Venta, and found a large deletion was homozygous in such dogs.

Palamino and Buckskin horses are heterozygous fro another mutation in this same SLC45a2 gene, and cremello and perlino horses are homozygous (Mariat et al. 2003). A mutation in this same gene is humans is said to cause one form of albinism.

To my eye, the photo of the Doberman at the left shows that the area that would have been black with normal SLC45A2 copies is a slightly different shade than the areas that would have been tan. This seems to indicate that although both eumelanin and phaeomelanin pigments are affected, they are not quite equally affected. However, many white Dobermans on people's webpages do not show this. It could be that this is not always the case, or that some photos are photoshopped to emphasize the whiteness.

This Lhasa Apso exhibits the classic characteristics of an albino but we did not find a mutation in the coding sequence of her Tyrosinase gene, nor did she have the deletion in SLC45a2 (Wijesena and Schmutz, WCGALP 2014), discovered in white Dobermans (Winkler et al. 2013). However, she had another mutation in SLC45A2, as did several other small long-haired breeds of dogs.

She had pups of normal coat and nose colored when bred by a colored dog, suggesting her albinism was a recessive mutation.

We had a small amount of DNA from an albino Pug, and she did not have either of these SLC45A2 mutations. This suggests this is at least one more mutation in this gene, or another gene, causing albinism in dogs.


White Coat with Pigmented Eyelids

Some white dogs have blue eyes. This dog has normal sight, vision and smell and leads a happy and active life on a farm! One should not assume that all blue-eyed dogs have problems or that they are "albino". Note the black nose and eye rims on this dog. No one has shown the genetic basis yet for either white coat or blue eyes, or even if they are caused by the same gene! Jasper was the only one in his a litter of white pups to have blue eyes which suggests a different gene may be involved.


Some German Shepherd dogs are called white. Quest, at the left and the other white GSD we have studied have an "e/e" genotype at the MC1R gene or E locus. This could explain why they have no black pigment on their hairs. But why aren't they reddish? That must be caused by another gene that has not yet been determined. Danielle LaGrave has helped us obtain DNA samples from White Shepherds and Samoyeds.

This family of Akitas shows a single cream female pup with her 4 fawn brothers. Although one might first assume that she has diluted both phaeomelanin and eumelanin, this is not the case. She is "e/e" in genotype and therefore would have no black hairs, and so she has diluted her only pigment, red, to cream. It seems coincidental that she is homozygous for "e" from two heterozygous parents and also homozygous for an allele like "i" but this seems the best explanation at the moment for her cream/white color. Tyrosinase alleles did not co-segregate in this family so the gene causing this is not known yet.

The Caucasian Mountain Dog is another breed in which cream pups are "e/e".

The Miniature Schnauzer is another breed in which the "e/e" dogs appear white or "silver", illustrated by Tasmin at the left. Note that the classic black-and-tan pattern caused by an "at/at" genotype at the agouti locus is called black-and-silver in this breed. It would seem that all phaeomelanin pigmentation is diluted to a white or silver in Miniature Schnauzers.

Likewise in Puli, the white dogs have an "e/e" genotype as shown by MacIntosh on the right. However some Puli that are "e/e" have a hint of reddish pigmentation as shown on the separate page about Puli color.

  • Schmutz, S. M., T. G. Berryere. The Genetics of Cream Coat Color in Dogs. Journal of Heredity, in press, 2007.
  • http://jhered.oxfordjournals.org/cgi/reprint/esm018v1?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=Schmutz-SM&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT


    Samoyeds, such as Mitzi, are typically white. We have genotyped only 3 Samoyeds but interestingly all were "e/e" at MC1R and also "a/a" at the agouti locus. Sue Ann Bowling suggested we study such dogs. Are they white because the don't make black pigment in their hairs because of "e/e" and also can not make red pigment because they are "a/a"? There could be yet another gene involved, but this is a very intriguing hypothesis.


    This white Samoyed/Husky cross has a black nose and eyes and is therefore not a classic albino. Little suggested that the white of Samoyeds is due to the allele (sw), which he claims is the lowest allele of the series at spotting, meaning it is the most recessive in that series. However, this crossbred suggests that Samoyed white may be dominant or epistatic.


    No data are yet available for which gene actually causes this white or the white of Great Pyrenees. Great Pyrenees often have a few colored spots on their head and some on their skin. Their white may be caused by a gene that affects pigment migration into the hairs or pigment migration embryologically.


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