Canine Coat and Nose Color Testing

Presence of black color, tan points and mask.
Staffordshire Bull Terriers occur in black or fawn red or shades thereof such as blue, with or without some white markings or brindle markings. Some appear almost completely white. There are two "a" alleles at the agouti locus in Staffordshire Bull Terriers (a^y and a^t). The black-and-tan pattern is undesirable; therefore, dogs that are a^y a^y are preferred. Staffordshire Bull Terriers may be brindle or solid colored. Dogs that have at least one a^y allele, will be full-body brindles (except where white markings occur). Dogs that are a^t a^t will have brindle only on their "points", i.e. they will be brindle where they would otherwise have had tan. Black dogs with brindle points are not disqualified in some countries, even though they are a^t a^t. At the present time, DNA testing is not yet available to detect the brindle allele. Solid black dogs, with or without white markings, are caused by the presence of a K allele in this breed. DNA testing is not yet available to detect the alleles at the K locus.
DNA testing is also not available for white markings or spotting. DNA testing for the "a" alleles in Staffordshire Bull Terriers that are solid colored or black-and-tan allows breeders to better predict the colors of pups from particular matings. Both E^m and E alleles occur at the E locus. E^m causes a black mask. This mask is not visible on black dogs, nor easily visible on brindle dogs, but is obvious on fawn red dogs.