UC Davis School of Veterinary Medicine Veterinary Genetics Laboratory
Dog Coat Color MC1R - Mask - Grizzle

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In dogs the production of the two pigments eumelanin (black) and pheomelanin (red/yellow/cream) is controlled by the Melanocortin 1 Receptor (MC1R) gene, also known as Extension. The four alleles (variants) of this gene are, in order of dominance: melanistic mask (Em), grizzle (Eg), black (E) and red (e). Some dog breeds are fixed for either black or red pigment, such as the Large Munsterlander for black and Irish Setters for red.

Melanistic face mask is found in a variety of breeds including but not limited to Afghans, Akitas, Boxers, French Bulldogs, German Shepherds, Great Danes, Greyhounds, Pug Dogs and Whippets. For Pug Dogs and Boxers the trait is fixed, while it is variable in other breeds. Dogs that are overall eumelanistic (black, blue or brown) may have the mask but it is indistinguishable from the body color. Dogs with white muzzles may have the mask gene but expression is overridden by white spotting patterns. The mask phenotype is caused by the Em variant at the MC1R gene.  

Grizzle (also called domino) is a pattern of dark pigment (eumelanin) on the dorsal surface of the head, body and tops of the legs; light pigment (pheomelanin) is present on the lower legs, undersides and up the face around the eyes. The distinctive face pattern is often referred to as a widow’s peak. This variant has been seen in Afghan, Borzoi, Chart Polski, Saluki and Silken Windhound. Grizzle can only be expressed when the Dominant black gene is not present (N/N) and the agouti gene is at/at.

The VGL test for MC1R screens for all 4 variants to provide a complete analysis of the genotype of a dog for this gene and a better understanding of phenotype and breeding expectations.

Results are reported as:

Em/Em

2 copies of mask- dog has mask

Em/Eg

1 copy of mask and 1 copy of grizzle- dog has mask and carries grizzle

Em/E

1 copy of mask and 1 copy of black- dog has mask and carries black

Em/e

1 copy  of mask and 1 copy of red/yellow- dog has mask and carries red/yellow/cream

Eg/Eg

2 copies of grizzle-dog is grizzle if Dominant black is N/N and agouti is at/at

Eg/E

1 copy of grizzle and 1 copy of black- dog is grizzle if Dominant black is N/N and agouti is at/at

Eg/e

1 copy of grizzle and 1 copy of red/yellow/cream-dog is grizzle if Dominant black is N/N and agouti is at/at

E/E

2 copies of black

E/e

1 copy of black and 1 copy of red/yellow/cream

e/e

2 copies of red/yellow are present. Dog is red/yellow/cream

 

References:

Schmutz SM, TG Berryere, NM Ellinwood, JA Kerns and GS Barsh. MC1R studies in dogs with melanistic mask or brindle patterns. Journal of Heredity 94:69-73 (2003)

Newton JM, AL Wilkie, L He et al. Melanocortin 1 receptor variation in the domestic dog. Mammalian Genome 11:24-30 (2000)

Dreger DL and SM Schmutz.  A new mutation in MC1R explains a coat color phenotype in 2 “old” breeds: Saluki and Afghan hounds. Journal of Heredity 101 (5):644-649 (2010)

Veterinary Genetics Laboratory, Tel 530-752-2211, Email VGL