VetGen - Veterinary Genetic Services

Genetic Testing Available for Unusual Labrador Colors

When one thinks of the Labrador Retriever an image comes to mind of a breed that comes in three colors:  black, chocolate, and yellow.  Dogs which have the appearance and behavior of a Labrador, but are not one of these colors are often assumed to be something else.  Looks can be deceiving, however, because the basic genes that control coat color are the same in every breed.  This leads to the sporadic appearance of unusually colored animals.

There are genetic tests available for some of these unusual colors and patterns. For those who care, these provide a tool to manage the outcome of future litters.  The variations of most interest to Labrador breeders are silver, brindle and tan point.  Another common sort of unusual color is the appearance of black or chocolate blotches on a yellow dog.  These are generally the result of a mutation in the animal as it is developing and are not inherited.  Since there is no predictive test, they will not be discussed further.

There has been a lot of attention paid recently to the silver Labrador.  These dogs have inherited a recessive copy (d) of the Dilute locus gene from each of their parents. The result is that these dogs do not produce as much pigment in their coat as is normally present.  This makes an otherwise black dog appear grey as seen in some Newfoundlands, while a genetically chocolate dog will appear the color of a Weimaraner.  Both colors are sometimes called silver although it is more common to see dilute black called charcoal and dilute chocolate called silver.  Simply testing for the recessive d in prospective mates will allow a breeder to know if silver is a potential outcome.

More commonly, a litter may show up with a surprise pup or two that are either tan point like a Doberman or a Rottweiler, the same pattern with brindle in the points, or even brindle all over.  Historically, the brindle and tan point variations have been noted since the inception of the breed.  They have always been there, simply at a very low frequency.

They are due to variations in the genes at the K (dominant black) and A (agouti) loci.  Most Labradors have two copies of the KB version of the K locus gene.  Only a single copy is necessary to make a black or chocolate dog be of a solid color.  About 1 in 25 Labradors carry one of two recessive versions of this gene, either ky or kbr.  When two such dogs are bred about 25% of the puppies will not be solid colored.  Usually these pups will be tan point or brindle point because the vast majority of Labradors also have two copies of the tan point version of the A locus gene.  The pattern is normally hidden because of the presence of a KB in most Labradors.  Some puppies may have other versions of the A locus gene than “tan points” and in such cases a dog may be brindle all over.  All of these surprise colors may be predicted or avoided by testing prospective mates for the K locus.  As long as one parent is KB/KB all the puppies will be solid in color.

For more detailed information on the genes involved in coat color, one can visit the Vetgen site at www.vetgen.com.  There is also information there on the genetic disease testing that we offer for the Labrador Retriever. 

Rob Loechel

Vetgen, L.L.C.

www.vetgen.com