Which K-locus allele is dominant: solid black or brindle?

The solid black allele (K 

B

 ) is dominant over the brindle mutation (K 

Br

 ).

On the K-locus (the CBD103 gene), the solid black allele (K 

B

 ) is the most dominant version of the gene. While the brindle allele (K 

Br

 ) is dominant over the most recessive allele for fawn and points (K 

y

 It remains recessive to the dominant black allele. Therefore, a dog only needs one copy of the K 

B

  allele to have a solid base coat, which will override and hide any brindle trait.