Overview: Black Bulldogs are the most common of the 4 Rare Colors in AKC English Bulldogs. The black should be shiny & look black against black objects or in the sun unless the seal gene is involved which can show a different color undertone to the black coat. These dogs may or may not have a fawn undercoat when the hair is rubbed backwards. The nose, footpads, & eyeliner are always a true black.
As in all the Tri Colors (3 colors on the dog one of which is always the tan points), the tan points are typically on the eyebrows, cheeks, front shoulders (right above the chest area between the legs), around the tail, and partial on both front & back legs. Tan points will not show up if the dog is white where the points would normally be. Tan points can also be hidden by other genes, such as the SEAL gene, as it is higher on the hierarchy of genes. Tan points can bleed through on some dogs when only one [at] is present. It normally takes a double [atat] dog to show tan points. As of this writing, the geneticists do not know why this happens on some dogs with the same dna & not others.
It is my thinking that Sable EB's that show tan points &/or have dark etching, DO carry one [at] & are ayat in their dna. A TRUE Fawn (red based dog) will not show sable hairs, tan points, or dark etching & will be ayay in their DNA. To back this up, we conducted a private study to back up our thinking.
ay, at, a, aw
Agouti aka ASIP gene interacts with the MC1R gene to control red and black pigment switching in most dogs.
Dog coat color is further complicated when other genes restrict agouti expression for example the dominant black gene-K. There are 4 known alleles of agouti. They are listed in order of Dominance:
1. ay- fawn or sable which expresses in shades of yellow to red with some dorsal black tipped hairs.
2. aw-Wild Sable expressing as banded hairs of yellow and black.
3. at-Black and Tan black expressing as dorsal hairs with tan hair on cheeks, eyebrows and undersides.
4. a-Recessive Black expressing as all black
The agouti test can help determine the color of dogs that have white patterns that may obscure the distribution of the colored pigment.
ay / ay 2 copies of fawn
ay / aw Dog is fawn and carries 1 copy of wild sable
ay / at Dog is fawn and carries 1 copy black and tan
ay / a Dog is fawn and carries 1 copy of recessive black
aw/ aw 2 copies of wild sable
aw/ at Dog is wild sable and carries 1 copy of black and tan
aw/ a Dog is wild sable and carries 1 copy of recessive black
at/ at 2 copies of for black and tan
at/ a Dog is black and tan and carries 1 copy of recessive black
a/a 2 copies of recessive black
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