UC Davis School of Veterinary Medicine Veterinary Genetics Laboratory
Dog Coat Color Brown (Chocolate/Liver) Test


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TYRP1 Gene. There are two alleles: the dominant full color (B) and the recessive brown (b). Two copies of brown are needed to dilute black pigment to brown. For red or yellow dogs, the brown allele does not dilute the hair color, but will change the color of nose and foot pads from black to brown if two brown alleles are present.

Brown results are reported as:

B/B: Does not carry brown - cannot have brown offspring

B/b: 1 copy of brown present - carrier

 b/b: 2 copies of brown present - black pigment (if present) is diluted to brown,  red/yellow dogs have brown noses and foot pads

*Note regarding French Bulldogs: The dark chocolate color will not be detected by the brown gene test. The genetic basis for this color is not known at this time.


Schmutz SM, TG Berryere and AD Goldfinch. TYRP1 and MC1r genotypes and their effects on coat color in dogs. Mammalian Genome 13:380-387 (2002)

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)

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