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Cocoa Locus (CO-LOCUS) is a mutation that can lead to brown/chocolate coat color in French Bulldogs previously known as “non-testable chocolate”. There are several known mutations in the TYRP1 gene (B-LOCUS) that can lead to a brown/chocolate coat color in dogs. Even though these mutations account for the brown/chocolate coat color in most dogs, a brown/chocolate coat color in French bulldogs can be due to an additional unique mutation located in the HPS3 gene. This coat color is referred to as “Cocoa” and can be visibly darker brown than the coat color seen in dogs with the typical TYRP1 mutations. The CO-LOCUS mutation can have a complex inheritance in combination with the B-LOCUS mutations that is still being studied. It is currently believed that one copy of the CO-LOCUS mutation and one copy of B-LOCUS mutation will not result in a brown phenotype.

A mutation in the TYRP1 gene (B locus) is responsible for the presence of brown/chocolate/liver color in the coats, noses and foot pads in many dog breeds. This coat color can sometimes be referred to as “red” in breeds such as Doberman Pinschers and Australian Shepherds.  Three separate and distinct mutations can occur in the TYRP1 gene which leads to a change in the production of the black pigment known as eumelanin.  A dog can inherit any two of the three mutations which dilutes the black color pigment into a brown color within the dog’s coat, nose and foot pads.  A dog must have two copies of any of the three TYRP1 recessive mutations (also represented as the “b” allele) to express brown/chocolate/liver color in their coat, nose and foot pads.

A mutation in the TYRP1 gene (B locus) is responsible for the presence of brown/chocolate/liver color in the coats, noses and foot pads in many dog breeds. This coat color can sometimes be referred to as “red” in breeds such as Doberman Pinschers and Australian Shepherds. Three separate and distinct mutations can occur in the TYRP1 gene which leads to a change in the production of the black pigment known as eumelanin. A dog can inherit any two of the three mutations which dilutes the black color pigment into a brown color within the dog’s coat, nose and foot pads. A dog must have two copies of any of the three TYRP1 recessive mutations (also represented as the “b” allele) to express brown/chocolate/liver color in their coat, nose and foot pads. It’s important to note that some breeds have additional mutations that can lead to brown/chocolate/liver coloring and these mutations have yet to be identified in breeds such as French Bulldogs.