This webpage is part of a series on Dog Coat Color Genetics. It was first mounted by 2006, and was last updated on January 13, 2011 by Sheila Schmutz firstname.lastname@example.org
|Some but not all Whippets, Greyhounds, Afghans, Great Danes, French Bulldogs have black masks, which Little suggested is due to an allele at MC1r (EM). However, the Whippet is a pale solid color (fawn), and the Akita is sable whereas the Great Dane Banjo, on the brindle page, is both brindle and masked. Little suggested that masked was dominant to its absence on fawn or brindle dogs. The mutation causing mask has recently been found in the MC1R allele by our lab and is offered as a test by Healthgene.|
The mechanism by which a black mask is formed is an interaction between the MC1R or E gene with the agouti protein and melanocyte stimulating hormone. The EM allele allows agouti to bind some of the time and cause fawn pigment to be made on the body and the melanocyte stimulating hormone to bind on the face instead. Because of this any phaeomelanin pigmented dog (i.e. yellow, fawn, red, cream) with a mask, must be so colored due to an agouti genotype. Such dogs can not be "e/e" at MC1R because an Em allele is required for the production of a melanistic mask. This further confirms that dogs in breeds where mask is part of the standard such as Bullmastiffs and Boxers, the reddish coat colors are due to the agouti alleles and not an e/e genotype at MC1R.
Since the mask is inherited as a dominant trait, a dog could be heterozygous or homozygous for mask. The extent of the mask or depth of color do not seem to be affected by the number of copies of Em. Melanin pigment can be black, grey or brown and therefore the term "melanistic" mask includes all these types of masks.
Some dogs with melanistic mask have premature greying of the muzzle but this does not seem to be correlated with whether they are homozygous or heterozygous for mask. Bridget is only 22 months old in this photo.
Since eumelanin occurs in black, brown and blue/grey, the melanistic mask can occur in any of these colors. Manner, on the right, is a fawn Chinese Shar-Pei with a brown mask.
Only some French Bulldogs have melanistic masks of black hairs but this breed has considerable black pigmented skin on the muzzle which sometimes shows through the pale hairs, as illustrated by Sadie at the left whose genotype is "e/e" at MC1R. Note that Sadie has no black hairs but still has some black skin and black nose leather and pads.
Jester, a Kerry Blue Terrier, has the genotype EM/E. He is about 8 months old in the photo on the left and about 3 in the photo on the right. His coat has changed from black to blue but his black mask, called "points" in this breed, did not change. This change to "blue" is called "clearing" in Kerry Blue Terriers.
Masks are present on all Bull Mastiffs and Pugs. Masks would not be visible on black, brown or born blue dogs, however, only fawn, cream, or red ones.
All Boxers have masks too but sometimes they are born completely or almost white. Such white Boxers carry the allele for mask, even if they don't show it. Riley and Thibault both have a trace of a black mask though.
Some coat patterns such as Harlequin, merle and Irish spotting can make it impossible to see the mask. Pirate is a Harlequin Great Dane that carries the EM allele, but his mask doesn't show. Likewise dogs that are black or brown or blue do not show their mask against their similar body color.
Breeds in which the DNA change causing Melanistic Mask has been detected
In some breeds all dogs have a mask. This is called "fixed" in genetic lingo since the trait is fixed and never varies. "Variable" in the table below means some individuals in the breed have a mask and others do not.
|Breed Name||Fixed or Variable|
|Cardigan Welsh Corgi||Variable|
|Kerry Blue Terrier||Variable|
Some dogs, like Malamutes for example, have white facial markings. This pattern is not the type of mask that Little studied. This pattern is probably not caused by the E or MC1R locus but the gene causing it has not been identified yet. In Akitas, such as Chili, this is called "urajiro" markings.
A similar facial marking in Afghans is called "Domino" after a famous dog with this pattern. In Salukis it is called "grizzle". Although both have a facial pattern similar to this, they have different body markings. See the Saluki or Afghan page for more about the genotype causing these patterns.