The “Silver Lab” Controversy

Silver Labrador

I’ve been called a “snob” because of my stance on the “silver Lab” controversy.

While some may see me as a “snob”, I prefer to see myself as well informed.

But if I am more educated than a “breeder”, then there’s a problem.

So, what’s this all about?

 

Silver Labrador

 

The picture above is a “silver Labrador.”

You will notice that each time that I use this term I use quotation marks, there is a good reason for this.

Let me explain…

 

A Quick Run Down on Genetics

I’m not looking to give you a degree in genetics, so let’s just run over the basics that you need to know for this article.

Living organisms are made up of cells.

Inside our cells are little packages of DNA called chromosomes.

The DNA inside those chromosomes is comprised of segments that are called genes.

These DNA segments, or genes, are what make us individually us. That is to say, our genes are what determine what we look like, piece by piece.

There are many different types of genes – it is estimated that the human body has between 20,000 to 25,000 genes!

These genes are “coded” by something called alleles. It is the alleles that tell the genes the specifics of the traits that are being built. So if a gene expresses eye color, the alleles would be what tells the gene which color to express.

The alleles that code a gene can be dominant or recessive.

Unlike dominant traits. recessive traits require the presence of multiple recessive alleles for the trait to be expressed. If  a dominant allele is present in any pair of alleles it will override any presence of a recessive allele.

Genes and their alleles influence many different aspects of our being, many of which – like eye color – are observable, where many others – like hemophilia – are not.

 

        DNA in Dogs

 
Now, the average human being is made up of 23 pairs of chromosomes, or 46 chromosomes in total.

When we are conceived, each parent “donates” one-half of each chromosome pair so that each chromosome is a combination of both parents.

So what determines which parent’s genes win out when it comes to what we look like?

It’s all in the alleles.

 

The traits that are “activated” or displayed are influenced by the specific alleles in the genes that we inherit from our parents. The dominant alleles win out.

To look at this in an overly simplified way – if the two alleles of an eye color gene “donated” from your mother are dominant, but the two alleles “donated” from your father are recessive, your mother’s alleles will override your fathers in terms of the trait displayed.

I’ll cover this in more depth in the next section when we get down to the nitty-gritty.

 

Black Lab Puppy

 

The Basic Genetics of Labrador Coat Coloration

All dogs have a wide range of genes that can influence their appearance just like humans.

As in the example above, the alleles of the coat color genes affect how coat color is expressed in a dog. Now, things get a little more complicated as we get into a real world example, because there are many different genes that can influence the appearance of a dog’s coat.

Want an example? The ticking that appears on the coat of a pointer is thought to have its own gene. Ticking is also thought to be a dominant trait. This means that if a dog has an active ticking gene and that gene has a T allele, then that dog will have ticking on their coat. If they have an active ticking gene but they have the recessive t allele and no dominant T allele, then they will not exhibit ticking.

Now, not all dogs have the ticking gene “activated” or “turned on”, however. This is why only certain breeds display a ticking pattern. Labradors, for example, do not have the ticking gene turned on, so you will never see a labrador with ticking on its coat.

Think of it like this…the dog’s genes are like light switches. All dogs have these switches (genes), but only some dogs have them turned on (for example, the ticking gene). Now, out of the dogs that have these switches turned on, not all of them have lightbulbs (the dominant T allele) in the light socket, so the light doesn’t come on despite the switch being turned on.

There are many different genes or “switches” like the ticking gene, that can be turned off in different breeds. This turning on and off of genes is what helps to distinguish the appearance of different breeds from one another.

 

Now, let’s get to our Labradors…

There are four possible alleles – E, e, B, and b – that contribute to Labrador coat color.

“B” and “E” represent the dominant coat color alleles and “b” and “e” represent the recessive color alleles.

A dog has two E gene allele locations – one from each parent – and B gene allele locations – one from each parent.

There are hard and fast rules that go into which colorations result from which allele combinations. These are the result of dominant and recessive allele combinations.

Take a look at the table below.

 

Yellow A yellow lab will always occur in a dog that has an ‘ee’ pairing of alleles. For example eeBB, eeBb, and eebb
Black A black lab will always occur in a dog with one ‘E’ and one ‘B’ allele. For example EEBB, EeBB, EEBb, EeBb, and EeBb.
Chocolate A chocolate lab will always occur in a dog with a ‘bb’ pairing of alleles and a single ‘E’ allele. For example EEbb and Eebb.

 

What does this information mean? It means that both yellow and chocolate coloration in Labradors are linked to the expression of recessive alleles. So, if both parents do not carry that recessive allele, then there will be no chocolate or yellow colored puppies in the litter.

As we talked about above, alleles are given to the puppy by their parents. In this case, each parent gives an E or e and a B or b gene. The end combination of the allele pairs is written in a four-letter notation which represents each allele pair given by each parent dog such as “EEBB”.

If you remember drawing “punnet squares” in biology to determine potential offspring characteristics, this is the same thing.

Confused? Let’s look at an example that might clear it up.

It’s time for the punnet square….

 

Female →

EB Eb eB eb

Male ↓

EB

EEBB
(Black)
EEBb
(Black)
EeBB
(Black)

EeBb
(Black)

Eb

EEBb
(Black)
EeBb (chocolate) EeBb
(Black)

Eebb (chocolate)

eB

EeBB
(Black)

eeBB
(Black)
EeBB
(yellow)

eeBb
(yellow)

eb Eebb
(Black)
eeBb (chocolate) eeBb
(yellow)

eebb
(yellow with liver colored eye rims/nose aka a “Dudley” caused by the ‘bb’ allele pair)

 

The punnet square above shows all of the allele combination possibilities for the Labrador breed.

For example…

A female with EEBb genetic makeup is a black female, but she also has the possibility of producing chocolate puppies because she carries the E and B alleles.

This female must give her puppies one of each gene allele, so she could give her puppies an EB or Eb combination.

Consider that she is bred to a male.

The male has an EEbb genetic makeup. This means that he is a chocolate male.

This male could give his puppies an Eb combination only.

Using the punnet square above, you can see the possibilities of puppy colors.

Puppies can have:

An EB from mom and an Eb from dad which means they would be EEBb or black puppies that carry chocolate due to the presence of the E and B alleles.

An Eb from mom and an Eb from dad which means they would be EEbb or chocolate puppies.

This combination of parental genes can result in only two genetic combinations which will result in chocolate and black puppies.

Why? Because in order for any yellow puppies to present in a litter, each parent must carry an ‘e’ allele.

The Dilute Gene

 

So where do silver labs come from?

There’s no silver in that punnet square, so what does silver have to do with anything?

Well, there is a ‘D’ gene.

This gene is referred to as the ‘dilute’ gene.

The dilute gene acts upon the ‘B’ gene and results in a diluted coloration.

The ‘D’ gene is a recessive gene which means that in order for a dog’s coat to be diluted, it must have two recessive alleles for the ‘D’ gene.

For example, a black dog that inherits two recessive dilute alleles from its parents will present with a “blue” color. We see this color in other breeds like “blue” Dobermans, but not in the Labrador breed.

A chocolate dog that inherits two recessive dilute alleles from its parents will present with a “silver” color. Again, we see this color often in other breeds like the Weimaraner, but not the Labrador breed.

So if Labradors don’t exhibit these diluted colors, what does this mean?

It means that at some point, that ‘D’ gene had to be activated.

The gene must be “turned on” in the dog without that active gene by a dog with that active gene.

This is one reason why a great number of people believe that the “silver Labrador” is actually a cross between the chocolate Labrador and the Weimaraner. The Weim. has that dilute gene and through selective breeding, it can be introduced and expressed in a chocolate dog of any breed.

 

Chocolate Lab Puppy

 

So What Does it All Mean?

It means that “silver” is not a “natural” color to the Labrador breed as it was initially bred.

It means that dogs are being crossbred purposefully to introduce a physical characteristic into the breed.

Is this such a bad thing, though? Weren’t all purebreds originally from crossbreeding?

Well, the issue that many purists have with this breeding practice in Labradors is that it is being done for no more than appearance.

Adding dilution to a color has no functional purpose for the breed, it is done for visual appeal only, for novelty.

The general rule of being a good breeder is a dedication to the betterment of the breed – breeding for health and function to continue the legacy of the breed. Breeding for a unique color that is often priced much higher because of its novelty, is far from a dedication to the betterment of a breed.

In fact, it’s somewhat reminiscent of the backyard breeder, isn’t it?

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