Pigment in yellow Labradors
(portions by Laura Michaels - Woodhaven/Kelrobin
Labradors)
First off there are two distinct
yellows that have different "genotypes" which means
genetic combinations for color. If a yellow Lab has one or
two genes that encodes for black then the dog will have black
pigment and this pigment can vary in intensity which I will
discuss below. If a yellow Lab has two genes that encode for
chocolate then the dog will have liver (chocolate) pigment
also known as a "Dudley"
and this can vary from very light flesh colored on a light
yellow to a dark brown on a red or dark yellow. These different
combinations can arise from various breedings depending on
what color the parents are AND what colors they carry. Two
blacks bred together for example can produce both black pigmented
yellows AND liver pigmented yellows.
Here are examples.
This first dog is a dark yellow
with black pigment. Notice the black around his muzzle and
eyerims. His nose has faded to pink due to age. This inevitably
happens to most yellows. It is often called a "winter"
or "snow" nose. The cause is a breakdown of a certain
enzyme (tyrosinase) that produces pigment. As a dog ages this
enzyme doesn't work as well and so the nose fades. It is also
temperature dependent so the enzyme works better in the warm
months of the summer thus the nose will fade back to black
or purple in that season.
Now here is a dark yellow
with liver pigment. Notice that not only is his nose brown
but also his lips and eyerims.
Here is an example of a young
dog with black pigment.
Here is an example of a 3
year old yellow with black pigment whose nose has begun to
fade.
Now pigment on black nosed
yellows can vary. Some have very little black around the eyes
and muzzle. Some have noses that begin to fade as puppies
and never turn back to black while others keep their coal
black noses until they are seniors (8 years +). Most begin
to fade around 2 years of age. Usually pigment does darken
as a young pup ages and if the nose is purplish at say 5 -
6 weeks it will most likely turn black by 8 weeks but not
always. Intensity of black igment is controlled by a separate
set of genes to coat color. Breeding a poorly pigmented yellow
back to a black may not correct the pigment in the resulting
puppies. The best way to do so is to go to a yellow dog with
really good black pigment or a black or even chocolate that
is from a line with good pigmented yellows.
Liver nosed yellows can be predicted in some breedings but
many times they come as a surprise so some responsible knowledgable
breeders will produce them from time to time. The most common
case is the breeding of chocolate to chocolate. It is relatively
uncommon for a chocolate to carry yellow so the chances of
BOTH parents carrying the color are slim but it does happen.
Yellow and chocolate genes can be passed down the generations
and so some assume that say a black doesn't carry chocolate
because no chocolates appear in the pedigree for many generations
but that is not always so. The black could carry BOTH yellow
and chocolate and be bred to a yellow that happens to carry
chocolate and voila both types of yellow pups can arise.
You can know definitively
in some cases especially if a stud has been used enough times
and only produced one or two colors. If a black that carries
yellow is bred to another black that carries yellow then there
is no chance of producing a yellow with liver pigment. If
you don't know for sure what each parent carried then the
only sure why to tell what colors your dog carries is to have
them color tested through DNA coding which costs about $85.00.
Unfortunately many breeders
are not well versed in coat color genetics and there are "old
wives tales" surrounding liver nosed yellows. First of
all they are a fault, not a disqualification. Only a
dog that has true pink pigment can't be shown so producing
a beautiful pup that can't go in the ring is unfortunate BUT
they do make wonderful companions and hunting partners so
not all is lost! Second they do NOT have inherent skin problems
nor do they get sun burned like many breeders have been told.
They are "self colored" just like a chocolate Lab
or a red Visla and there is nothing genetically wrong with
that combination that makes their skin sensitive. And lastly
they do not "pop" up in litters that can't produce
the genetic possibility. In other words both parents MUST
carry both chocolate and yellow to yield liver nosed yellows.
A true Dudley (pink pigment)
can and generally do have the tendancy to sunburn, so you
do need to be careful of them in the sunlight.
One more note. Many other breeds allow a yellow/tan
coat to be paired with liver pigmentation in their standards.
These include the Pointer, Setter, Beagle, Shar-pei, Chow
Chow, Chihuahua plus many others. In the Labrador the originators
of the standard simply did not like the appearance of the
liver nosed yellows. Back in the early part of the twentieth
century when the Labrador was being cultivated in the U.K.
chocolates AND yellows tended to have very light eyes (like
a Chessie) which gave them a harsh expression. The original
Labrador standard called only for black coats and then yellows
were actually given a separate standard but they were soon
incorporated in with the black coated individuals. Chocolates
were always present because liver is recessive to black in
all dogs. Once the three colors were recognized in the standard,
the combination of chocolate and yellow was not asthetically
pleasing to those that were breeding Labradors and thus they
were frowned upon.
DUDLEY
What is a Dudley? You're
going to get different answers from different people.
A true Dudley is totally lacking in pigment.
Its nose, eye rims and feet are as pink as the day they are
born. 
Now, remember, the origins
referred to the Bulldog with liver pigment. In other breeds,
it has come to mean non-pigmented, as it does in the Standard
for the Labrador.
Many say a yellow with liver
pigment is a Dudley. It depends on the person and their definitions.
The AKC describes it as flesh colored. In Anna Katherine Nichols
book of the Labrador Retriever, written in 1983, the Dudley
nose is defined as flesh colored.
The LRC defines a Dudley as
pink. A yellow with chocolate pigment, whether its light
or dark, is not a Dudley. It should be penalized, but
not disqualified.
The AKC standard states:
The DQ for pigment reads, "A thoroughly pink nose or
one lacking in any pigment."
In the Canadian standard, it states that the yellow's pigment
is black or dark brown. Anything else is a serious fault (as
the Dudley nose in the US had been throughout history).
A yellow with a brown/chocolate
nose is NOT lacking in pigment, so they are not a Dudley and
should not be referred to as such.
The dog above could not be
shown, but the lack of pigment does NOT mean it can't still
be a beloved pet.
Yellow
Lab Pigment
