Brindle Labs

This week, I come to you with some useful(less) information about Brindle Labs- something I only recently discovered exists.

How did I come by this information?

I know, I know. Puppies. Santa Hat. The smile on that pups face. Are you melting?? If you aren’t, are you human?

Now focus a little closer and look at the paws on these pups. Wait! Black lab in the face, something else on the paws. Yes, I know the next question- and yes, they are pure bred Labrador Retrievers. In today’s post I explore a bit about Labrador genetics and how two parents who never showed any signs of discoloration came out with 3 brindle labs.

DID YOU KNOW?

The Labrador Retriever, according to the American Kennel Club is ranked #1 in popularity out of 193 breeds. They are sporty, friendly, social, and most commonly referred to as the top of the line when it comes to family pets. With their amazingly soft ears and what looks like a never ending smile – how can you not like them?

According to the AKC there are only 3 permissible colors to a Labrador Retriever.

As stated on the AKC site:

As a biologist, this absolutely intrigues me. If only the 3 colors are permissible, then what is a brindle lab? To answer this question, let us first lets looks at what makes Lab coloring.

Unlike what you might think, Lab coloration is not based on just one gene. I had always assumed that black = dominant and chocolate = recessive with Yellow being the combination of a dominant and recessive gene (and I’m a biology teacher – oops). It is actually the result of two different genes, one coding for Black and Chocolate and a separate gene coding for yellow. These are referred to as the B gene and the E gene.

Before your eyes glaze over (like my husbands did), here is a visual graphic to help bring home the basics.

The basics of this image shows that if the dog has at least 1 B and no ee, it will always be black. If the dog has ee, regardless of the B gene, it will always be yellow. And if the dog has bb (two copies of the recessive b) it will be chocolate (unless in the presence of ee). This is why chocolate is the least common, due to the fact that it cannot have a B or ee in order to show this trait. Black is most common, because all the dog needs is 1 B and at least 1 E and it is black. Though the presence of two recessive ee will beat out any combo and make the lab yellow.

So what is brindle?

Brindle is defined as : a brownish or tawny color of animal fur, with streaks of other color. It is fairly common in breeds, such as Boxers, but incredibly rare in pure bred Labs.

My first example of this cool coloration comes from our newest addition to the family, Rosalee a.k.a. Rosie. My little girl was 1 of 3 brindle labs to come out of her litter.

This is Rosie’s twin sister, Luna. Check out her beautiful brindle coloration, she has slightly more golden colored fur on her left paw.

So are brindle labs pure bred?

The simple answer is YES. Although, even our vet had assumed that there must be a mix of something in there. Most people, like me, have never seen a pure bred brindle Lab. When you see a pure bred Labrador Retriever, most think of solid coloration. The mixed color of a brindle can often be confusing. But lets take a look at our girls parents:

Mom, is a pure-bred black Lab (left image) and Dad is pure-bred yellow Lab (right picture)

These two have mated before. Their previous litter consisted of 8 pups: 4 black, 3 yellow, and one chocolate. Looking at that in genetic terms, we know that Dad has the ee gene making him yellow, but also that he must carry at least 1 b gene. Mom must carry at least 1 e gene, to make yellow pups, and 1  b gene creating the 1 chocolate pup. So, the nerdy biologist in me knows that the parents are most likely – Dad eeBb x Mom EeBb.

But, this still doesn’t explain brindle. So what gene is responsible for that?

This is actually due to another gene, not the standard B and E genes that we think about when predicting lab coat color.

“[More commonly], a litter may show up with a surprise pup or two that are either tan point like a Doberman or a Rottweiler, the same pattern with brindle in the points, or even brindle all over.”   www.vetgen.com .

What we have learned is that this gene is actually at the K locus. For most labs their K gene is dominant, which is why we note most labs as solid colors. In the case of brindle labs, they have the recessive version of the K gene, known as kbr. Approximately 1/25 of pure bred Labs have this recessive trait. These genes are so rare to show up in the litter because the K is completely dominant over the kbr.  Meaning that the only way for brindle to show is if both parents donate a recessive, meaning the pup has a kbr from both parents.  If you have two dogs with a copy of the recessive you should see 1/4 of the dogs will not be purely one color. As in our case, after a litter of all solid color pups, the second mating between these parents the recessive K gene was passed on by both parents creating 3/10 with the recessive trait and therefore brindle. As you can tell, this makes it very hard for any breeder to know the likelihood of brindle pups.

Has this gene always been a part of pure-bred Labs?

Again, the simple answer is yes. Labrador Retrievers were first recognized by the English Kennel Club in 1903, and later in the U.S. in 1917. The majority of Labs in the beginning were black, with yellow being the less frequent color. Chocolate Labs weren’t recognized by the AKC until the 1930’s, probably due to their recessive inheritance pattern.

According to vetgen.com:

“Historically, the brindle and tan point variations have been noted since the inception of the breed.  They have always been there, simply at a very low frequency.”

The brindle coloration, although not recognized as a color by the AKC, has been around since the beginning of the breed. Making it a little confusing why they do not recognize it as they did when the chocolate coloration came about, since it is just a matter of recessive genes being passed down.

Are brindle labs desirable?

Obviously this is a matter of preference. Some breeders may use the uniqueness of the coat color to charge more for dogs like this. It could even be something that they breed for if demand for unique Labs is up. I had never heard of brindle before picking out my Rosie. We were planning on getting a yellow until my kids saw pups with brown feet and they were in love. For us, we thought they were so different and embraced that.

The AKC does not permit brindle coloration, making me believe the majority of breeders do not prefer this in their litters. Many might even give a discount for pups that do not come out with solid coloration and cannot be pedigree dogs.

I guess it is all comes down to a matter of preference.

I hope you have learned a lot about the genetics of Labrador’s coat colors and enjoyed images of my families’ adorable pups.

Do you have a brindle Lab? Leave a pic in the comments of your brindle, tan point, or unique colored pooch.