Agouti Locus A Locus 900x600 1

The A-Locus interacts with E-Locus to regulate when and where phaeomelanin or eumelanin will be produced in a pattern. Different alleles cause either clear sable, shaded sable, agouti, saddle pattern, tan points or recessive black. A-Locus Overview The Agouti-Locus affects the temporal and spatial distribution of phaeomelanin and eumelanin. Together with the E-Locus and K-Locus, … Read more


Extension Locus E Locus 900x600 1

The E-Locus defines how much eumelanin can be expressed. Different alleles can cause melanistic masks, domino, grizzle and cocker sable phenotypes or recessive red coat. E-Locus Overview The Extension-Locus was named a long time before genetic testing was available. It got its name because it can extend the amount of black to yellow pigment in … Read more

Recessive Red (Recessive Yellow, ee-Red)

Recessive Red 900x600 1

Recessive red (ee) causes a dog to only produce phaeomelanin in all pigmented areas. Since the color intensity ranges from white up to yellow, orange and red this causes a variety of phenotypes. Many dog breeds with solid white, yellow or red coats are in fact ee-red. What is Recessive Red? Usually, pigment cells can … Read more

Cocker Sable (eH)

eH Cocker Sable 900x600 1

The eH allele at the E-Locus causes an interesting phenotype in Cocker Spaniels that either resembles a regular sable pattern or is described as a dirty red color pattern. Both of these phenotypes are actually caused by a version of domino similar to eA or eG in other breeds. What is Cocker Sable? The eH … Read more

Sighthound Domino – Grizzle (eG)

Sighthound Grizzle Domino Coat Color 900x600 1

The eG allele at the E-Locus modifies any regular coat color pattern by reducing eumelanin and increasing phaeomelanin production. This causes different new phenotypes mainly found in sighthound breeds where it is mostly known as grizzle or domino. What is Domino or Grizzle in Sighthounds? Domino changes any background pattern by decreasing eumelanin expression and … Read more

Ancient Domino – Northern Domino (eA)

Northern Domino Coat Color 900x600 1

The recently discovered eA allele at the E-Locus is responsible for a particular phenotype with reduced eumelanin production and increased pheomelanin expression. In northern breeds this is called northern domino, but in other breeds this is known as pied or grizzle. What is Ancient Domino? Domino reduces eumelanin expression and increases phaeomelanin expression. But it … Read more

Seal and Ghost Tan

Seal Dog Coat Color 900x600 1

Seal causes a more or less pronounced golden, red or brown sheen on a black coat. This is often accompanied by a darker dorsal stripe and darker coloration on the lower legs, tail and face. Seal and ghost tan seem to be caused by incomplete dominant black that can’t fully mask a dog’s A-Locus pattern. … Read more


K Locus 900x600 1

The K-Locus controls the agouti gene expression in canine coat. Different combinations of K-Locus alleles can cause dominant black, brindle or normal agouti gene expression. K-Locus Overview The K-Locus is named for the solid blacK coat it can cause in dominant black dogs[4,5]. The alleles at the K locus seem to follow a complete dominant-recessive … Read more

Dominant Black (KB)

Dominant Black KB Dogs 900x600 1

The dominant allele at the K-Locus (KB) inhibits the production of phaeomelanin and causes a solid eumelanin-pigmented phenotype in dogs that is commonly called dominant black. Here we look at the variations and genetics of dominant black coat in dogs. What is Dominant Black? The KB allele at the K-Locus promotes eumelanin synthesis and blocks … Read more

Brindle (kbr)

Brindle Dogs 900x600 1

Brindle (kbr) is a color pattern causing black, blue, brown or lilac stripes on a red or yellow base color. Here we look at the variations and genetics of brindle coat in dogs. What is Brindle? Brindle appears in dogs that express an A-Locus pattern (clear sable, shaded sable, agouti, saddle back or tan point). … Read more