Silver Labs – More Info

The New Zealand Kennel Club Breed Standard states –

Colour – ‘Wholly black, yellow or liver/chocolate. Yellows range from light cream to red fox. Small white spot on chest permissible’.

Eyes – brown or hazel

This standard is identical to that of UK, Australia, FCI and everywhere else excepting USA where in addition to the above they also state “that any other coat colour is a disqualification”.

For as long as there have been Labrador Retrievers in New Zealand there have been blacks, yellows and chocolates. Good responsible breeders select for good structure, working ability, good movement, temperament, type, proper coat and tail etc etc and the colour is whatever the colour is.

Black Labradors have always been predominant because black is the dominant colour in the breed.

As a background for those interested in genetics please read below.

There are many genes are involved in canine coat colour.  Genes sit at a locus (a location on a chromosome – plural loci) and the genes themselves can be expressed in different forms (called alleles) at the same locus. The generally recognised loci which control colour in dogs are called ‘A’(agouti), ‘B’(brown), ‘C’(albino series), ‘D’(blue dilution), ‘E’ (extension), ‘G’ (graying), ‘M’(merle), ‘R’(roaning), ‘S’ (white spotting) and ‘T’(ticking.) There may be more as yet unrecognised colour gene series, and in a given breed modifying factors may drastically affect the actual appearance.

Each gene influences the production of a protein. The effect on coat colour is to influence the production and distribution of black/brown pigment (eumelanin) or red/yellow pigment (phaeomelanin)

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 we are looking at.

In the Labrador Retriever the loci that dictate colour are the ‘B’(the brown/black series) and ‘E’(the extension series) loci. Genes at other loci like ‘C’ for albino, ‘D’ for blue dilution, ‘T’ for ticking and ‘M’ for merle are always turned off. Other loci like the ‘A’(agouti) always have present the allele for solid coat colour and this is never changed within the breed – ie every Labrador carries the same allele (the gene with that particular expression).

We know that if a Labrador has BB or Bb at the black/brown locus then black is dominant and the dog is black. If it has bb then the dog is chocolate. However the E gene acts as a “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 the double recessive ee then it will always be yellow no matter what is present at the B gene. A yellow that has a dominant B gene (eeBB or eeBb) will have typical black pigment on the nose, lips, and eye rims and a yellow that is homozygous recessive at the B locus (eebb) will have pale chocolate pigment.

The variations in the yellow colour recognized in the Breed Standard are due to modifying factors that influence the ‘E’ locus alleles. There are no variations of colour in black or chocolate Labradors.

The reason that the Breed Standard in the USA has the extra line about ‘disqualification’ is because the colour ‘silver’ appeared in the breed in that country a few decades ago. This colour has not appeared in any other country and has not been seen in New Zealand until 2006 when imported Labradors from USA produced progeny.

The silver/charcoal/blue coloration comes into play when the ‘D’ gene is turned on.

Please note that in the Labrador Retriever the ‘D’ gene is turned off just like the ‘M’ gene, the ‘C’ gene, the ‘R’ gene and more – which is why you do not get merle Labradors, albino Labradors or roan Labradors.

If the D gene is in it’s homozygous recessive form (dd) then it will “dilute” the colour expression of the B locus. The dilute version of chocolate (bb) is a silver colour and the dilute version of a black (Bb or BB) yields a dog that is dark slate gray or “blue”.

Weimaraners are a breed that is based on this ‘dd’ dilution. A typical Weimaraner coat is a mousey grey and this is because their ‘D’ and ‘B’ genes are both present in the homozygous recessive forms (dd and bb). Most Weimaraners thus are a chocolate colour that is diluted and they are a silver grey. They also can carry the ‘B’ gene in the dominant form so therefore a darker blue Weimaraner can occur in litters when they are dd and BB.

How the “silver gene” was introduced into the Labrador in the USA cannot at this time be proven but because it seemed to originate from one kennels it is most likely an accidental or deliberate mating with another breed. There is reference that the kennels in the USA from which the colour may have originated years ago at the time bred both Labradors and other hunting breeds including Weimaraner’s. Others have suggested it may have been that the colour was a natural mutation. Mutations however typically do not reproduce in a typical pattern. The ‘silver’ Lab expression follows the exact same pattern as any other (dd) dilution in other breeds. The ‘silver’colour has not been seen in any other country.

In USA the American Kennel Club registers Labradors that have this silver/blue dilution as either black or chocolate. Applications to NZKC for registration are being made in a similar manner.

The Labrador Retriever Club Inc of USA on it’s website has the statement that

“There is no genetic basis for the silver gene in Labradors. The silver color is a disqualification under the Standard for the breed. The LRC does not recognize, accept or condone the sale or advertising of any Labrador as a ‘silver’ Labrador. The Club opposes the practice of registering silver as chocolate.”

Breeding for colour alone increases the risk of other ‘unhealthy’ traits being seen in the resulting progeny and so such breeding demands very great care and substantial knowledge. Breeding for a colour that does not conform to the Breed Standard for the Labrador Retriever is totally inappropriate. It also has even greater risks for the progeny because of the small gene pool carrying the ‘dd’ dilution.

Below are links that you may wish to look at regarding the “silver issue”