A Primer on the Genetics of Color

The Tan Point, Brindle, or Mosaic Labrador are rare. 

 This page focuses more on the White Spotting which is more commonly seen.

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Many a breeder and many a poor Dam has been accused of miss-mating when a litter includes a few Black or Chocolate Dogs with white spotting on their chest or when a puppy or two were born with tan points, brindling, or even those very rare "mosaics". 

No matter how the Breeder might protest that there was no way any puppy in the litter couldn’t be from the Sire they had used, the accusers would walk away shaking their heads still believing that puppy just couldn’t be a pure-bred lab. Buyers walked away and Breeders scorned other breeders…until it would happen in one of their own litters.

You will even see debate raging on various social media platforms today despite all the knowledge that we have gained from genetic testing. Those who still maintain that a miss-marked Labrador is the result of an accidental pairing do so out of an ignorance of the science which proves them wrong. 

If you’ve ever learned the history of the Breed, you know that the ancestors of the Labrador were black and white coated St. Johns Water Dogs. With the goal of producing a solid black dog, the old-timers would only breed dogs with the most black in their coats; eventually, they were able to breed solid black to solid black until they consistently were producing litters with mostly solid black dogs. But even then, there would be a few “liver coated” dogs or “yellow coated” dogs; and sometimes, a black dog with white on its chest.

Those old-timers continued for many generations to breed black to black removing the other colored dogs from their breeding programs but the gene responsible for the expression of white hairs was still being passed down generation to generation just as the genes for liver (chocolate) and yellow coated dogs were.

Because the old-time breeders bred only black to black, the gene pool was small enough that most of those solid black dogs carried two copies of "S" and no copy of "s" so the white inherited from the St. Johns Water Dog did not “express” itself very often. And this rarity is what led to the common belief that a “miss-mating” had taken place and the poor black or chocolate lab with the white on its chest or the yellow with a lot of white expressed was a “mutt”.

Eventually, a closed kennel which produced litters bound to provide some service, would from time to time see white spots on the chests of Labrador puppies born under strict controls; controls that meant that there was no possibility of a miss-mating. This was evidence that there was some recessive gene that was causing pure-bred dogs to express those white hairs.

Science eventually proved that to be true, but even before that, the AKC and Labrador Retriever Clubs rewrote the Breed Standard to state that “a white spot on the chest is acceptable but not desirable” in dogs that were shown in breed competitions acknowledging that these dogs were in fact, pure-bred Labradors.

We know now that white hairs originate from the S Locus. The non-mutated form (S) makes it possible for a dog to express a few white hairs or none at all. It is a roll of the dice. The recessive version (s) of the gene means that the dog will express what is known as “white spotting”. And a dog with two copies of the mutated version (ss) will be solid white.

The two main genes for coat color in Labradors are "B" and "E" and each puppy receives one copy of each gene from each parent; these genes follow the Dominant/Recessive expression where "B" cancels "b" and "E" cancels "e". So, a puppy getting BB is not going to be Chocolate nor is a puppy getting Bb because the "B" cancels or hides the "b". 

It is the same for the "E" gene; in order for a dog to be yellow, it must get two copies of "e". The "S" gene however is co-dominant and therefore only one copy of the mutated "s" will result in expression of the recessive which is the expression of white. 

And we also know now that the “red” that is sometimes seen in a Black or Chocolate coat and quite often in the traditional Yellow coat in what is known as the “Fox Red” comes from the “A” locus as does the more rare tan points and brindling and even perhaps the mosaic.

So,  if someone tells you that your pure-bred puppy with some white on it's chest or a white ring around its tail isn’t pure-bred, all you need to reply is “DNA says differently”. Your puppy is every ounce a pure-bred Labrador from genetically tested parents descended from the black and white St. Johns Water Dog - the first Labrador retrievers.

Summing it up:

Genotype is hidden while Phenotype is seen

B = Black; b = Chocolate; E - no Yellow; e = Yellow; KB = solid; S=White

(There is also "A" which is responsible for the red tint seen in some dogs and for the tan point, brindle and mosaic labradors and "C" which determines the shading in the Yellow coats,  but for the purpose of this page, we are focusing only on the genes named above.)

A Black Labrador can have one of the following  genotype:

BB/EE/KB-KB/SS - no hidden Chocolate or Yellow, Solid Colored, may express a few white hairs

Bb/EE/KB-KB/SS - hidden Chocolate, no hidden Yellow, Solid Colored, may express a few white hairs

BB/Ee/KB-KB/SS - no hidden Chocolate, hidden Yellow, Solid Colored, may express a few white hairs

Bb/Ee/KB-KB/SS - hidden Chocolate, hidden Yellow, Solid Colored, may express a few white hairs

BB/EE/KB-KB/Ss - no hidden Chocolate or Yellow, Solid Colored but with white spotting

Bb/EE/KB-KB/Ss - hidden Chocolate, no hidden Yellow, Solid Colored but with white spotting

BB/Ee/KB-KB/Ss- no hidden Chocolate, hidden Yellow, Solid Colored but with white spotting

Bb/Ee/KB-KB/Ss - hidden Chocolate, hidden Yellow, Solid Colored but with white spotting