Seal Bulldogs

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Dominant Black K Locus | Seal | Brindle

KK, KN, NN

Coat colors in mammals is achieved by the production of two pigments, eumelanin aka black, and pheomelanin aka red or yellow. Most of the time, these 2 pigments are controlled by MC1R and Agouti genes. Coat color research in dogs has shown that a third gene, Dominant Black, K locus is involved. This gene produces either dominant black, brindle, and fawn color. The Seal Color is also somehow produced involving this gene.

RESULTS (UCDavis) 

K/K      2 copies of dominant black, dog will be visibly trindle, seal, or brindle

K/N     1 copy of dominant black, dog will be visibly trindle, seal, or brindle

N/N     Dog does not have the dominant black mutation

The genes that cause dogs to be Brindle are not yet fully understood, even by the scientists themselves. What we do know so far is that one of the markers on the K gene, specifically Kbr, is responsible for the brindle color on the coat, whether it be a partial or full brindleing, such as the Tan Points being brindled, which is what we call Trindle. The agouti gene overrides the brindle gene on the dogs body coat & makes it look solid color, except for any area where the dog is tan pointed or white. 

The K gene is confusingly called Dominant Black, because this gene shows as brindle, and black (seal). ALL brindle dogs carry at least one K gene. It takes only one since it is a Dominant gene to show on the dog.