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. The SEAL gene covers or hides brindle and tan points (agouti), as it is higher on the hierarchy of genes.
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 (seal) or brindle.
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 pattern 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.
To determine if the K Gene is Kb aka Seal, or Kbr aka Brindle, a visual inspection is needed. If the dog has brindle markings, the the K is Kbr. But if the dog appears solid color except for white areas, then the dog is Kb, or Seal which covers or hides any brindle present. It also covers or hides tan points.
Some wonder if the dog is seal can it also have or not have brindle. Yes! But the only way to determine this is if the breeder knows for a fact that both parents do not have brindle, OR, to breed to a clear, non seal dog and have 2 or 3 litters with Clear (non-brindle) pups.
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.
Just sharing DNA info from phone conference with scientists at UCDavis.
DNA Information. Dominant Black and Recessive Black. For the Bulldog breed.
Straight from the Scientists at UCDavis. Remember, even the scientists have to add info, &/or make corrections from time to time as new science is uncovered involving color genes in dogs.
First let me say that this writing will be based on the lettering that UCDavis uses for results. This is important, because a lot of people use Vet Gen and their lettering for the same results is different, which can be very confusing. ALSO, we are completely leaving out the brindle pattern on dogs for this discussion, because they can be (K), but the below statements will not always apply to them. There is much more study needed to figure out the brindle pattern in dogs.
As we all know, the color genes are in order of dominance. The dominant black (k) gene comes before the recessive black (a) gene, so if (K) is present, even just one, the genes at agouti will NOT present on the dog. Although the genes at agouti can be passed on, they will not show on the dog passing them if (K) is present.
1st point: (K) is a Dominant Gene, so unlike the other color genes, you need only one side to be (K) in order for the dog to be black. So all our black dogs (the ones that are black from this particular gene), can be either (KK) or (KN) and will present as black dogs. Again, these dogs block anything at agouti. This is why there has been much confusion as to why some black to black matings have produced standard color puppies. Say both parents are (KN), and both pass the (N) side to the same puppy. Then you would have a fawn based puppy, not a black based puppy.
2nd point: I love this one! If your dog is (KK), then EVERY puppy this dog produces will be black (or black based) no matter what the other parent. I have to test this out! But, I am now wondering if this is why Chroma (our black & tan Stud) has had ONLY Black & Tan/Black Tri puppies from EVERY litter he has thrown so far, with all different color Moms. We will be doing DNA on him to see if he is (KK).
3rd point: What about the agouti? The only way this can present on your dog is he/she is (NN) at dominant black. (NN) allows whatever the dog is at agouti to show on the dog. You would think that if the dog was (NN) it would be fawn in color or red based. BUT, if the dog is (NN-atat), Black & Tan, at agouti, then this dog would be black based from agouti & would therefore present as black & tan or black tri as some call it when white is present. If the dog is (NN-ayat) at agouti, then the dog would present as fawn or red based.
4th point: This is concerning the dog that is (NNayat). Since the agouti is recessive, you need to have both sides for the color to present. BUT, for some reason, (ayat) dogs can show some tan points, because the tan points can “Bleed Through”, and show on the dog.
5th point: When I speak of black (black based), and fawn (red based) dogs in this writing, remember that the other genes apply here too. For instance, if a dog is produced that is (dd), blue, then all the info above would apply as to whether this dog will be True Blue (black based), or Blue fawn (red based).
Author: Rare Bulldogs 9-21-12k this up, we conducted a private study to back up our thinking.
The genes that cause dogs to be SEAL are still not fully understood by even the Scientists themselves. What we do know so far, is that one of the K genes, (there are 3 series that we know of on the K gene) specifically Kb seems to be responsible for the seal coloring, which can be Black Seal, Chocolate Seal, Blue Seal, or Lilac Seal. These dogs shine through a different color, usually red, but can be fawn, gray, or even green shades, from under the coat, especially in the sun. They are most always only 2 colors, the second color being white, as this particular K gene HIDES the color at agouti, so any tan points if present will be hidden. True SEAL dogs will DNA [KbN ayay] [KbN ayat] [KbN atat] [KbKb ayay] [KbKb ayat] [KbKb atat]. Note: some labs will render results of a Kbr dog as Kb, which is NOT SEAL but Brindle.
The K gene has 3 parts to it. It is a modifier gene, not a color gene. Which means it tells some of the other genes on the hierarchy how to act...whether they can show on the dog or not. This is what the geneticists at UCDavis related to me: Kbr is associated with brindle, Kb is associated with black, and Ky or N is associated with fawn.
Not to make this any harder but the Kb or self-color gene is not only modified by the b and d dilution genes but also the Kbr, and the Agouti locus. They change the shade of the coat color. If a dog is KB, Kbr the seal coat will have a darker color and some seals even look pure black and white. If they are Kb, Ky and ayay in the A Locus they would have been a fawn or red dog, so the fawn or red background changes the color shade of the coat. This is why the seals can look different shades of colors.
The K Gene is confusingly called the Dominant Black Gene. This is confusing because only one part (of the 3 parts) of the K gene, specifically the Kb part, will render Black or black base on a dog. The other 2 parts render brindle or fawn/sable on the dog. That being said, the Dominant part is correct in that the dog needs only ONE Kb to show black or black base.
To Rare Color Breeders, this is VERY important, important on 2 ends of the spectrum. The first is positive in that the dog can have black & black based dogs with ANY female even if she does not carry color. The second not so positive is that this only happens 50% of the time, so only apprx. 50% of the litter will be black or black based. To add to that even the SEAL dogs that carry Black & tan [ayat] at agouti will still have some fawn/sable/brindle puppies in the litter. Each Black gene is only a 50/50 chance on every puppy. If you are breeding to a double [atat] dog, this can eliminate your double [atat] dogs 100% chance of having all black or all black based litters, you still render fawn/sable/brindle in the litter and this goes down to 25% in fawn/sable/brindle dogs when bred to a SEAL.
My point: You need to ask for dna of both black genes when breeding to a SEAL dog. Why would you breed down (dna wise that is) with your [atat] dog, and cut your chances of black or black based puppies even more when using a fawn/sable/brindle mate, especially on your females. Our EB females will at best give us 4 litters & most of the time only 3 if they are not over bred. Don’t eliminate the number of your possible true color productions by breeding the wrong DNA.
The only way to avoid the above scenario is to breed to a double [atat] dog or if you need the SEAL in your program, use one that is also double [atat]….KbN atat, not KbN ayay, or KbN ayat. You would get ALL black & black based puppies this way. Also, when breeding your ayat fawn/sable/brindle dogs with a double [atat] SEAL it increases your chances of getting the full black base from 25% to 75%, because a double [atat] SEAL dog throws black at 150%.
Copyright Rare Bulldogs 2014
Author Alesia Dixon
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