Whippet Color Genetics 101

These two litters of puppies are like a bag of jelly beans - all different colors and patterns.  

They just happen to demonstrate really well how some of the basic genetics controlling color in the whippet work.

There are various genes that control expression of many subtleties in coat color and pattern, and we won't get into most of that.

However, if you are curious to know why one pup in a litter can be all black, another all brindle and a third all red, or if you want to know how one litter can have pups that are nearly all colored and another pup in another litter can be nearly all white, then Talley-Ho and follow me!

Let's explore color first.

The color of any whippet is located on their K locus, which is the name of a gene.  Each gene is made up of two alleles (one from each parent).

There are 3 possible alleles:

K - black color
kbr - brindle color
k - red (or fawn)

Here they are:

From left to right:  Red, Brindle, Black

The way these genes are expressed is that the K (or black gene) is dominant to the brindle and red genes.  The kbr (brindle gene) is dominant to red (or little k).  That means if even one of the 2 alleles that a pup has, has a big K (or black), then that pup will be black - no matter what the other allele is.

If there is no big K, but there is a kbr, then that pup will be brindle, no matter if the other allele is the little k.

The only way a pup can be red, is to have both alleles be little k.

If you're wondering why a black parent could have a red or brindle puppy, it is because that black parent must carry one of the recessive alleles - a kbr, or a little k.

So for the pups pictured above, we know the allele composition of both parents.  And therefore we can predict potential colors of their puppies, and the probabilities of getting those colors.

We can do this graphically - in the form of a Punnett square (remember 7th grade science class?):

So what this nifty picture says, is that Jett is a black dog (big K), carrying red (little k).  And Bella is a brindle dog (kbr), that carries the recessive little k (red).

Any puppy that Jett sires has a 50% chance of inheriting the big K (black) and a 50% chance of inheriting the little k (red).

And for Bella, any puppy has a 50% chance of inheriting the kbr (brindle), and a 50% chance of inheriting the little k (red).

When you put it all together, all of the possibilities are shown in each of the 4 squares.  If you remember that big K is dominant over all others, then there is a 50% chance that any pup will inherit the big K (or be black).  

The other 50% chance is that a pup will be anything BUT black (either kbr - brindle, or little k - red).  What the math predicts is 50% black pups, and 25% red pups, and 25% brindle pups.

So...what did we get?

We got:  50% black, 50% non-black dogs.  But we got 3 brindles and only 1 red.  If following the math perfectly, we would have gotten 2 brindles, 2 reds.  

This goes to show, each pup is a flip of the coin, as to what allele they actual inherit, so it's possible to beat the odds.

What about all the white?

So you might be asking where does the white fit in?  White is the absence of color - not a color that actually exists on a gene.

However, the amount of white a pup gets, and it's pattern are heritable.

So next, let's look at patterns.

There are 4 basic color patterns in the whippet, and just like color, the pups inherit the amount and patterns of white from their parents.  Even the location of where the white appears on any dog is dictated by genetics!

The gene that dictates white (absence of color) patterning is the S locus.

The four allele possibilities are:

S - solid, or self-colored (little or no white)

si - Irish (mostly colored, but with white trim on the neck, tip of tail, feet, chest, face, but no break in color on the body.)

sp - Piebald, Pari-colored (more or less equal amounts of base color and white)

sw - Extreme White (large areas of all white, with little or no base color)

Here are examples of the 4 patterns:

From left to right:  Solid (minimal to no white at all), Irish (neck, chest, feet, and tail tip are white - but not her butt), Parti (white neck, chest, legs, tail, and hip pattern tear-out), Extreme White (2 head patches, and one side patch - rest of the dog is white).

Same line up - showing pups from the front - varying amounts of white on faces, necks, legs, tail tips, & bodies.

In terms of dominance, Solid (S) trumps all.  Irish (si) is dominant over Parti (sp), and Extreme White (sw).  And Parti (sp) is dominant over Extreme White (sw).

To complicate matters even more, the S locus seems to be a bit messy in terms of just how dominant the different alleles are.  There are 'plus or minus modifers' than can overlap.  Sometimes, you get a lot more white than expected, and other times you don't!

By example:  Spicy is a parti, carrying extreme white (sp/sw), and Alfredo is an extreme white (sw/sw) - hence, we got about 50% extreme white pups in their litter.

But Bella & Jett are a little bit muddier.  Jett is an Irish, carrying parti (si/sp).  Bella is a solid, carrying extreme white (S/sw)...we think.  So this would explain the parti-colored pups in their litter, and you'd think we wouldn't be able to get any extreme whites from these parents, since parti trumps extreme white.  BUT, in a previous litter, they produced an extreme white dog!  That's the result of those pesky modifiers.

But what about the blues?

Ok, now we're cooking with gas!  There is one more area we'd like to cover in this very basic color exploration.

Why do some of the dogs have grey coloring in their coats (this is called 'blue' in whippets), and others have black?

A blue coloring is actually just a dilution of black.  (Just like the color gray in your crayon box is a dilution of the color black).

Here is a great example of black and blue:

Jett (left) - black.   Polli (right) - blue dilute.

The genetics for dilution of the black pigment are located on the D locus.  And it is a simple system with only two possible alleles:  D (dominant black) and d (recessive dilute).  For a Whippet to have the blue coloration, he has to have both alleles be little d  - as any dog carrying a big D will be black.  A D/d dog will look black but carry the dilute blue - which he or she could pass on to future offspring. 

When we talk about the little d, or dilute blue, we are talking about all black pigmentation and all black coat color.  So a blue dilute dog (d/d), also has a blue nose, lighter eyes (usually).  

Wherever there would be black (eyes, nose, paws, black stripes on a brindle dog, etc.), a blue dilute dog is blue instead of black in these areas.

By example, in Spicy and Alfredo's litter, we have quite a few dilute dogs.  Here is an example of a black brindle and a blue brindle:

 Dilute blue brindle (left) and non-dilute black brindle (right) - brothers from Spicy's litter.

Same pups - better shot of their stripes.   Blue brindle (top); black brindle (bottom).

To complicate the issue slightly, even in non-black dogs, there can be some black pigment that isn't related to the big K allele.  We see this in sable-ing, water-marking, masks, and other 'outlines' or whispers and accents of black.  If a dog is a blue dilute, these marks will be blue.

And once again, we have examples in our current puppies:

These are both red (k/k) puppies.  But the top one is red with D/d, and the bottom is blue fawn with d/d dilute.  If you're interested in thinking back to color patterns, they are both parti or piebald, and they both carry extreme white (since daddy Alfredo can only throw extreme white).

Notice that we didn't get a blue dog without brindle or fawn in these litters, like Polli who is pictured above.

This is because a blue dog without brindle or fawn would have to have at least one big K and two little d's.  

Neither Spicy (k/k) nor Alfredo (kbr/k) carries a big K. So they cannot produce a dog with a big K (expressing black), even though they can - and did - have blue dilute (little d) puppies.

In Spicy's litter, she's D/d, and Alfredo is d/d.  So all of the puppies at least carry one little d allele.  And about 50% of them are blue dilute (which you would predict from Punnett square calculations, and which we got, as 5 of the 9 pups are either blue fawn or blue brindle).

In Bella and Jett's litter, Jett (K/k) could (and did) produce black dogs.  And Bella is a dilute blue brindle (d/d).  BUT - Jett has 2 big D's, and therefore cannot produce blue puppies.  

That means all of the puppies in Bella's litter have a big D from Jett and little d from Bella.  So even though none of them are blue, they all carry it and could pass it on to their offspring.

Tying it all together.

This isn't everything there is to know about genetics and coat color and patterning in whippets, but it gets messy from here.   

And these concepts are the 'big ones' anyway.  If you understand these 3 genes (color, patterning, and dilutes), you'll be able to look at any whippet and understand where their color and pattern came from.  And you might even be able to predict what their parents looked like, and also what any of their offspring could look like.

As breeders, we find this not only fascinating, but important and thought sharing the info. would be fun.

If you're really into this and would like to know more, there is a fantastic website with lots of pictures and details about masks and reverse masks (no...those grey faces don't mean a whippet is old!), ticking (freckles), roaning, and patterning here:  http://runswiftwhippets.net/Genetics/Genetics%20old.html