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Huskies are a well-known and well-loved workhorse breed. Originally bred for sledding, they are one of the most athletic dog breeds in existence.
In addition to being very agile and ridiculously strong for their size, they have a reputation for being obedient and intelligent enough to learn complex tricks. They are also particularly well-loved for their affectionate disposition.
But they also have a unique physical trait that often sets them apart. Many of them have elegant, expressive blue eyes.
But why do Huskies have blue eyes, when brown is the most ubiquitous color of almost every other breed?
Blue eyes are even rarer in dogs than in humans. A handful of breeds, like Old English sheepdogs, border collies, and Welsh and Pembroke corgis, have the potential to be born with blue eyes.
But they are by far most common in huskies.
For a long time, scientists could only guess at why this was the case.
For example, past research has noted that some breeds, like Australian shepherds, will have light-colored eyes if they also have light coats. But this does not appear to be the case for huskies, who can have blue eyes regardless of the color of their coat.
Without much in the way of genetic data, there was no way to figure out why huskies bucked this trend. But that has all changed quite recently as new information has come to light.
Last year, researchers published the largest study to ever compare the genetic profiles of dogs. The study, published in the journal PLOS Genetics, tested the DNA of more than 6,000 dogs whose owners had purchased DNA testing kits for their dogs.
Normally such tests are for confirming a dog’s breed or looking for warnings of potential health issues down the road. This study, however, allowed researchers to a wellspring of data greater than any ever compiled before.
The methodology of this research is well-established. Many similar studies have already been conducted in humans. The idea is that, when you collect the genetic information of enough individuals, you can compare that data to pinpoint the genetic variations that cause anything from diseases to observable characteristics like blue eyes.
Thanks to the increasing popularity of mail-away DNA test for dogs, researchers have been able to do the same for dogs for the first time.
As referenced earlier, huskies are not the only breed that can have blue eyes. But they do appear to be the only breed to have blue eyes for the reason that they do.
Genetic traits are caused by haplotypes, which are sets of genetic variations that occur on a chromosome.
Past research found that blue eyes in merle and piebald dogs were caused by one of these variations that can also cause light or patchy coats. But the new research has found a husky’s blue eyes are caused by an entirely unrelated gene.
What researchers found was a genetic quirk near a gene known as ALX4 on canine chromosome 18. This gene plays a key role in how the eyes of mammals develop.
The result in the case of huskies is that their eyes develop with a lack of pigment, which gives them the appearance of having blue eyes.
You see, blue eyes are not actually caused by any blue pigment. No such pigment exists. So this mutation appears to result in a lack of pigmentation in the iris of a husky’s eye. The lack of pigmentation creates the appearance of a blue eye because of the way light enters and leaves the eye.
It works similarly to why the sky looks blue, even though outer space is not. Without getting into a whole physics lecture, light appears white to us under normal circumstances but is split when it passes through a prism. In this case, either the earth’s atmosphere or your husky’s eye acts as the prism.
The separated light is then scattered in all directions. Because blue light has the shortest wavelength, it is the color we tend to see most as the light scatters.
At least, that is the general idea.
Now because most dogs do not have this genetic grouping, their eyes have more pigment and therefore don’t scatter light as readily. The result is that their eyes appear brown or black to us.
Of course, huskies do not have blue eyes exclusively. They can have a wide range of colors, including blue, brown, hazel, or amber.
A unique quirk of theirs is that they commonly have two eyes of differing colors. Presumably, this is caused by a variation to that ALX4 gene giving a dog uneven pigment distribution across their eyes.
This variation can sometimes result in huskies having blue eyes with flecks or pie-shaped wedges of brown. This is quite common, and dogs with this coloration are called parti-eyed or split-eyed.
If you are raising husky puppies, you may notice that some of them lose their blue eyes as they grow.
This is completely normal. It does not have a cause necessarily. It is just the fact that at birth, all husky puppies appear to have blue eyes.
Huskies first open their eyes around two weeks of age, and over the next two or three weeks their eyes will take on the color that they will have for the rest of their lives.
So don’t fret if your newborn puppy’s eyes suddenly turn brown. It is just a part of them growing up.
Many owners have looked into their dog’s hypnotizing eyes and wondered just why do huskies have blue eyes. As fascinating as it is to learn why certain dogs have certain traits, the real takeaway is what this most recent DNA study will mean moving forward.
We will soon have the ability to single out genes that can cause health problems, and breeders will be able to take that information into account and select against those genes. This is a great step forward in raising new generations of happy, healthy dogs.