CHOCOLATE ENGLISH & FRENCH BULLDOGS

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The hair color on Choco's can vary slightly, but, there is no getting around the LIVER Colored nose. The nose, eyeliner, and pads should be some variation of brown, whether Hershey type chocolate or a more diluted chocolate as in chocolate fawn/sable. If the nose is not liver(brown) it is NOT A TRUE CHOCO! Chocolate color in dogs is no more than a Diluted Black dog. Contrary to popular thinking, the Chocolate bb (Brown/Liver) gene is really NOT a choco gene. It is a dilution gene which dilutes Black to Brown. For the Chocolate Gene to make, if you will, a dark chocolate dog, the BLACK base has to be there to be diluted. The eyes are often light gold, green, blue, or gray. In addition to the nose color, DNA Color testing will reveal the "bb" alleles in CHOCOLATE dogs. Each parent also contributes one of their two dilution factor genes to their offspring - either a brown (b) gene or a non-brown (B) gene. Chocolate parents (bb) can contribute only a brown (b) gene and non-brown parents (BB) can contribute only a non-brown gene (B). Choco Carriers can either contribute a non-brown (B) or a brown (b) gene. For more info, please refer to the Official Rare Color Chart.  

Genotype for Chocolate Gene: [bb] 

Overview: Chocolate Bulldogs are diluted black dogs from a different dilution gene than the blue. The chocolate coat should be shiny and look brown against black objects or in the sun, unless the seal gene is involved which can give different undertones to the coat. These dogs may or may not have a fawn undercoat when the hair is rubbed backwards. The nose, footpads, & eyeliner are always chocolate, even in the chocolate fawn.

Brown aka Chocolate

BB, Bb, bb

TYRP1 Gene. There are two alleles 1. B dominant full base color 2. b  recessive brown

TYRP1 is a modifier of eumelanin, not a dilution gene as in blue (dd). The dilution gene affects how dense the pigment is, which makes it appear pale as if you mixed white into black paint making gray. The chocolate bb does not dilute, but changes the shape of the molecules of the pigment. The different shape reflects light in a different way and therefore changes the black to chocolate.

When you have a bb dog, black pigment is modified to chocolate. If your dog is red or yellow base, the bb does not modify the hair color, but does modify nose, eyerims, and foot pads from black to chocolate and eye color to amber or gold.

RESULTS (UCDavis)

BB: Does not carry chocolate, full base color, cannot have chocolate offspring

Bb: Dog is base color and carries 1 copy of chocolate

bb: 2 copies of chocolate, full chocolate

DETAILS

The hair color on Chocolates can vary slightly, but, there is no getting around the LIVER Colored nose. The nose, eyeliner, and pads should be some variation of brown, whether Hershey type chocolate or a more diluted chocolate as in chocolate fawn/sable. If the nose is not liver (brown) it is not a true chocolate. Chocolate color in dogs is basically a modified Black dog, where black is modified to chocolate. For the Chocolate Gene to make a dark chocolate dog, the Full Black base has to be there.

The chocolate gene affects black pigment only. If a dog is bb, all of the black in the coat will be turned to chocolate. This includes all patterns. Chocolate turns the nose and eye color, usually to an amber, yellow, or gold color. The nose color is the best way to tell chocolate from a black or blue. When you combine a chocolate dog with a blue dog, bb + dd, you get a lilac, which is the color of a Weimaraner.

Chocolate is recessive, so it takes 2 copies to present on the dog. If a dog is full black base and is bb, all the black in its coat will become a chocolate. Bb and BB have no visible effect.

As if this were not confusing enough, I have now been advised that there are 3 Sequences to the b genotype. There are a number of different versions of the b allele, but all of them result in the same coat color. These variations mean you can have either b, b2, or b3 on your dog’s DNA. This can be on one or both sides of the complete gene.

Therefore, it is possible to have your dog dna any one of the following types:

Bb    Bb2    Bb3    bb    bb2    bb3    b2b    b2b2    b2b3    b3b    b3b2    b3b3

Some labs recognize all 3 sequences and some don't, so you could have a b2 or b3 on your dog and not know it.