I have English Bulldogs, what should I test my dogs for?

Many people are interested in testing a dog to see if they carry either the “blue gene” or the “chocolate gene”.  The “blue gene” is really a misnomer, as the dilution gene dilutes all types of pigment.  The dilute gene is recessive, so a dog must have two copies of that gene to appear dilute (diluted black pigment is termed ‘blue’, diluted chocolate pigment is termed ‘lilac’).  To test for the dilute gene, please indicate D-Locus testing on your submission form. 

To summarize, here are the potential genotypes for the Dilute gene.

The “chocolate gene” is what causes a dog to produce brown coat color, rather than black.  Thus, a dog that is chocolate will be chocolate-and-tan or chocolate tri, rather than a black-and-tan or standard tricolor.  Chocolate dogs will also have brown noses and pads.  The “chocolate gene” is also recessive, so a dog must have two copies of this allele to appear chocolate.  To test for the “chocolate gene”, please indicate B-Locus testing on your submission form.

To summarize, here are the potential genotypes for the Chocolate gene.

Often, breeders also want to test their English Bulldogs for “Black.”  This is tricky, as there is not one black gene, but several genes that can cause black coat color.  The Dominant Black gene (K-Locus) causes only black coat color to be produced.  White is actually an absence of color, so dominant black dogs can be solid black or black and white.  Dogs that not dominant black have their color determined by the Agouti gene. 

The Agouti gene can also cause dogs to appear black, depending on which genes the dog carries.  The Agouti allele that is the most dominant is the AY allele, which causes the fawn or sable coat color.  The allele that causes black-and-tan or tricolor coat color is the “at” allele, which is recessive to the AY allele.  A third allele causes the dog to appear solid black, which is the “a” allele.  This is the most recessive allele.

Here are the potential genotypes for a dog for the Dominant Black gene (K-Locus).
If the phenotype of the dog is “Agouti”, please look to the dog’s genotype for the Agouti gene (A-Locus) to determine his color.

Here are the potential genotypes for a dog for the Agouti gene:

Because you cannot test for the black-and-tan or “at” allele, testing at the AY- and a- Locus can determine if your dog carries that gene or not.  For example, if a Fawn dog tests AY/AY, he does not carry the black and tan gene.  However, if he tests n/AY, he only has 1 copy of the fawn allele.  The other copy must then either be the “at” or the “a” allele.  If that same dog then tests n/a for the a-Locus, you know he is AY/A.  If he tests n/n for the a-Locus, you he must be AY/at, and would carry a copy of the black and tan or tricolor gene.  Thus, to test for “black” in a fawn dog, please mark the A-Locus (AY) and the A-Locus (a) boxes on your form.

For a dog that is already black and tan or tricolor, you know he must be n/n for AY.  Here you may want to test for the recessive black gene to see if he has one or two copies of the black-and-tan or tricolor gene (at).   If your dog is tricolor or black and tan, please mark the A-Locus (a) box on your form.

A dog that is black or black and white can be tested for Dominant Black, or the K-Locus, to determine if he has 1 or 2 copies of the KB allele.  If he is KB/KB, he will always pass on the dominant black gene, and will always produce blacks or black and whites.  If he is n/KB, there is another allele present, so he will only pass on his dominant black color 50% of the time.  To test a black and white dog for the dominant black gene, please mark the K-Locus (KB) on your submission form.