http://www.woodhavenlabs.com/silverlabs.html
A dog's genetic makeup is very complex (like us) and many genes are involved in coat color. The same genes are all present in every dog however only certain ones get "turned on" like a switch and others are off depending on what breed or what goes into a puppy in the case of a mixed breed. A Labrador's coat color is dependent on many genes being turned on and off. The ones we commonly think of that dictate color in our breed are the B and E genes. Other genes like T for ticking is always turned off and still other genes like the A gene causes a dog's coat to be a solid color. We know that If a lab has BB or Bb then black is dominant and if it has bb then the dog is chocolate. However the E gene acts as a epistatic gene or "masking" gene; in other words if the dog has Ee or EE then the color is dependent on what is present at the B gene (BB, Bb, or bb) but if the dog has ee then it will always be yellow no matter what is present at the B gene. A yellow that has a dominant B gene (BB or Bb) will have typical black pigment on the nose, lips, and eyerims and a yellow that is homozygous recessive at the B gene (bb) will be a Dudley.
Now the silver coloration comes into play when the D gene is turned on. If the D gene is in it’s homozygous recessive form (dd) then it will "dilute" the coloration if the B gene. When chocolate is dilute the color is a silvery mousey brown and the dilute version of a black (Bb or BB) yields a dog that is dark slate gray or "blue". Weimeraners are a breed that is based on dilution. The typical Weim coat is a mousey gray and it’s because their D and B genes are both present in the homozygous recessive forms (dd and bb) so the typical Weim is a chocolate that is diluted. Weimeraners also can carry the B gene in the dominant form so therefore a darker blue Weim can pop up in litters when they are dd and BB. A breed like the Doberman also has this dilute gene pattern in it’s population and therefore "blue" Dobies arise from a dilute black Doberman and fawn is the dilution of a red Dobe. Other breeds like Great Danes, Chow Chows, and German Shepherds and even Newfoundlands can be diluted. Some breeds accept the color and others do not and if the dilution factor is present in a breed it is found the world over and is known to be in the population. The breeders of silver Labs originally thought that the color was a mutation. Mutations typically do not reproduce and if they do they do not follow a pattern. Silver Lab expression follows the exact same pattern as any other dilution in other breeds. Also as more silver breeders appear the darker blue color has arose because they introduced black into their breedings unlike the first silver breeders who assumed that only chocolate would produce silver.
I would suspect that silver Labs were a combination of a Labrador and a Weimaraner - they ALWAYS have the diluted D gene turned on (dd). This combo would produce a dog that would essentially look like a lab and if bred to a chocolate lab then the results would look and most likely act like labs (due to the Weim also being a gun dog and having a vaguely similar build and temperament when compared to many other breeds) - and the dilute gene could be "turned on" because of an introduction of this dilute combination. The resulting offspring could carry this - silver breeders comment that all silver puppies come from a silver x silver cross, and silver x chocolate give either silver puppies or chocolate puppies that carry silver. This would agree with the D gene hypothesis - two parents with dd would only give a d gene and the puppies would all have dd and would therefore be silver.
Through research I have found that all silver Labradors or Labs that carry the dilution factor can be traced back to two kennels in the U.S. They were breeders that stumbled upon the color and sought out to express it as often as possible and so pedigrees from the first silver Labs are the result of inbreedings like father to daughter and full sister to brother, etc. This was the only way they could keep the color going since other dogs would not yield the color and furthermore all other countries besides the U.S. have never even heard of a silver Lab. Both of these kennels had dogs that came from one kennel in particular which bred both retrieving and pointing breeds in the U.S. back in 20’s and 30’s. An old time west coast breeder actually remembers them advertising rare blue Labradors in Gun Dog magazine in the 50’s. So it is my theory that the dilution factor was added back then most likely by accident and breeders today are keeping it going.
There are many reasons why silver Labradors should not be produced and the main one is that they are a disqualification and adhering to a standard while breeding is what keeps a breed a breed. The Labrador looks and acts like Labrador and not a German Shepherd because of the dedicated breeders preserving the breed. A standard is a blueprint and varying because it looks nice will undoubtedly cause the structure to fail. Also silver breeders do not typically run health clearances on their breeding stock (OFA/CERF) nor do they participate in any competitions to prove their dogs are breeding quality. This leads me to believe that they are breeding simply to make money and do not care about a superior individual nor do they care about the breed in general.
Silver breeders also blatantly lie. They have information on their websites that talk about DNA testing done by the AKC and a researcher at UC Berkley. Both are not true. AKC never did any genetic mapping of silver Labradors nor do they have any plans to do so since they are a registering body only and the Labrador Club of America writes the standard for the breed. Also Dr. Neff at UC Berkley was never looking into whether or not silver Labs were purebred or not which is also a moot point since DNA testing can only prove parentage at this point and is not specific enough to search for breed markers.
"The Science Behind AKC DNA Profiles
AKC DNA Profiles are generated using the same technology used by law enforcement agencies throughout the world. How does this work? In humans and dogs alike, each gene is present as two copies (displayed as letters). Offspring receive one copy of each gene from each parent in a random process.
This technology does not use actual genes, but other DNA sequences that are also inherited one copy from each parent. For this reason, your dog's AKC DNA Profile does not provide any information about the conformation of the dog or the presence/absence of genetic diseases.* Furthermore, AKC DNA Profiles cannot determine the breed of a dog."
The color will never be recognized and it does not appear anywhere else in the world. A silver or blue Labrador can not be entered in a conformation event because they do not fit the standard even though they are erroneously registered as chocolate. If they really were a shade of chocolate like a cream or fox red is a shade of yellow then they could be shown.
So please be educated about the color and don’t pay the high price for a novelty. I have received numerous emails from silver owners whose dogs had many health and temperament problems. Buyer beware.
© 2005 Sharon A. Wagner
wigwag@adelphia.net
www.wigwaglabradors.com