Coat Color inheritance for Olde English Bulldogge puppies
Lilac, lilac tri, blue, blue tri, chocolate, and chocolate tri are all considered to be rare bulldog colors and presently the highest priced Olde English Bulldogge puppies on the market. Breeders that can produce these colors consistently have a good understanding of color inheritance patterns and the application of genetic principals. At Olde South Bulldogges we specialize in raising rare colored Olde English bulldogge puppies. Proprietor holds a degree in biochemistry with an emphasis in genetics. Please follow us at oldenglishbulldoggepuppies.com.
Color patterns are determined at the genetic level by genotypes and phenotypes. Geno=gene and deals with what the dogs actual genes look like, while pheno (think P is for picture) deals with what the dog physically looks like or the physical picture of the dog. You can also consider genotype is what is on the inside and phenotype is what is on the outside. There are several genetic locations on specific chromosomes (Loci) that genetically determine a dog’s color. At each location on these specific chromosomes is a gene. A gene is made up of 2 parts each called an allele. The location of a specific gene on a specific chromosome is called the loci for that gene. Each allele is assigned a letter to identify what the gene produces in the phenotype. If the letter is capitol that allele is dominant and if it is lower case the allele is recessive and masked by the dominant allele. In summary a gene has 2 parts and the dominant portion dictates what the gene will produce.
At the K loci is where the determination is made for brindle or fawn or solid black or chocolate. Possible alleles are KB, kbr, and ky. KB is dominant (solid black or brown like a chocolate lab or black lab), kbr is brindle, and ky is fawn. If a dog has 1 KB allele he will be solid black or solid chocolate. We can simplify this loci to a basic dominant-recessive relationship with “kbr” (brindle) being dominant over “ky” (fawn or non-brindle). “kbr-kbr” and “kbr-ky” would be brindle, while only “ky-ky” would be fawn (or non-brindle). A homozygous (which just means two of the same gene) brindle “kbr-kbr” would always produce brindle pups. This would be beneficial if one is trying to produce brindle-colored pups, or detrimental if one is trying to produce non-brindles. For a dog to be a Lilac or blue tri for example he must first have the kyky genotype. If the dog has just one K gene for solid black, they will only be black with no other coloration — K masks all other possible secondary colors on the A locus in the phenotype but they can be a carrier for the genes on the A locus.
At the B loci (we say B for brown) there are two alleles “B” and “b”. Bulldogges can either be “BB” or “Bb” (black). B is dominant to b so only those dogs with a “b-b” genotype will express the chocolate color. For example a chocolate lab might be KBKB on the K loci and bb on the B loci.
For blue, the Loci, or location is called “D” for dilution. The possible alleles (or genes) at the D loci are “D” and “d.” Every dog is either “D-D,” “D-d,” or “d-d.” These are the genotypes. A genotype of “D-D” produces a pheontype of non-dilute, or non-blue. The genotype “D-d” is what is typically called a “dilution-carrier.” These dogs have a phenotype exactly the same as “D-D”. They are non-dilutes. “D” is a dominant allele over “d” so only dogs which have a “d-d” genotype will have a blue, lilac or dilute phenotype. In other words, only “d-d” dogs are actually blue in color or lilac. Blue is a dilution which acts on black pigment as well as black-colored hairs. Any pigment or hairs that would otherwise be black are diluted from black to blue on a “d-d” dog. This is what makes solid blue, blue brindle, blue fawn, blue pied, blue with tan points, and all other varieties of blue possible. A lilac dog is always bb at the b locus. A lilac is a dilute chocolate. A blue is a dilute black. Lilac requires the recessive pair on the B locus bb. That is why it is rarer.
The A loci is the one responsible for the different variations of fawn and contributes to markings on tri dogs. Possible alleles are Ay, aw, at, and a. Ay is dominant (solid) fawn. aw is for wild (or the wolf-type grey color) and is responsible for the sable in some fawns of breeds other than bulldogs. at is responsible for tan points (black and tans). Lastly, a is recessive black. For example, a blue tri bulldogge would have to be ky (no dominant “K” or brindle), at at for fawn points, and have the dd recessive. All the recessive genes must occur in this combination. A blue tri is a very rare color combination and much higher in price because the chances of having a blue tri dog are very slim!
The Lilac is the most misunderstood. Lilac bulldogs are simply diluted chocolate. A lilac tri must be ky (non-bindle), bb (brown causes black to be a brown or chocolate color), dd (dilution gene to get the light chocolate coloring). A lilac dog would have no black or grey hairs. The nose is chocolate and eyes are blue or hazel. The recessive genes in this combination are very unlikely so we strongly recommend having a DNA test before purchase. A lilac tri would have to have the recessive pair of at alleles at the A locus as well.
Let us know if we can help you understand the color genetics of the bulldog. We appreciate any comments and contributions on this issue.