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Why Do Some Dogs Have Two Different Colored Eyes?

 

Why do some dogs have two different colored eyes? There are dogs with blue eyes, dogs with brown eyes and then there are dogs with eyes of different colors, how cool is that? While it’s quite a sight to see a dog with one blue eye and one brown eye, these dogs aren’t really that rare or unusual. There are several dog breeds with different colored eyes and in most cases this is just a genetic tweak. And just in case you’re wondering, consider that there is usually nothing wrong with the eyes of these fellows as their vision is normally not affected. So let’s take a closer look as to why some dogs have eyes of two colors.

Eye color is a matter of melanin
Eye color is a matter of melanin

A Matter of Melanin

The scientific name for dogs with two eyes of different color is complete heterochromia. Eye color in dogs is the result of different concentrations of melanin, a pigment that gives color to a dog’s skin, coat and eyes. The more the concentration of melanin, the darker the eye color. In dogs with different color of eyes, the concentration and distribution of melanin in both eyes is therefore not uniform. This means that in a dog with a brown eye and blue eye, the brown eye has a greater concentration of melanin when, on the other hand, the blue eye has considerably less.






husky eyes
Complete heterochromia in husky.

The Role of Genes

Complete heterochromia in dogs is for the most part hereditary. This means that it tends to be passed down genetically from one generation to another. Some breeders like to call dogs boasting different eye colors as being “bi-eyed.” Certain dog breeds appear to be more likely to develop eyes of different colors compared to others.  However, in some breeds, an eye of a different color is considered a serious fault more than an appealing feature. Here are some dog breeds that may have different colored eyes:

  • Siberian huskies. Different eye colors in this breed is not very uncommon; indeed, it’s even mentioned in the standard. According to the American Kennel Club Siberian husky standard, “eyes may be brown or blue in color; one of each or parti-colored. “
  • Australian Shepherds. According to USASA, the United States Australian Shepherd Association, an Aussie with a blue merle coat or red merle coat can sometimes have a blue eye and a brown eye.
  • Louisiana Catahoula Leopard Dogs. Other than huskies and Aussies, this all American dog breed may have the eyes each sporting a different color.
dog nuclear sclerosis
Bluish-grey haziness in nuclear sclerosis

An Eye Disorder

Remember how in the introduction we said that there’s usually nothing wrong with the eyes of dogs with different eye color? Well, in some cases, two eyes of different color in dogs may be due to an eye disorder. It’s not unheard of certain dog owners reporting that their dog has an eye that is changing color and is assuming a “bluish tint.” If your dog’s eyes are turning blue or cloudy, consider that there are several eye disorders that may cause the change of color. Cataracts, nuclear sclerosis, glaucoma, anterior uveitis and corneal dystrophy are five eye disorders that can cause blue eyes in dogs, explains veterinarian Dr. Becker.  If you notice a sudden onset of eye color change in your dog, consider that this can be indicative of an underlying medical condition, which therefore may warrant a complete eye exam by a veterinary ophthalmologist.




Other Types of Heterochromia

Sectoral heterochromia in dog
Sectoral heterochromia in dog

Complete heterochromia means that one eye is a different color of the other one, but interestingly, there are other forms of heterochromia in dogs. In sectoral heterochromia, the dog’s eye contains one color that is a completely different color from the remainder of the eye. This is sometimes found in the Australian shepherd, border collie, Welsh corgi,  Catahoula cur and great dane and several other breeds with the merle trait. Siberian huskies, which do not have the merle trait though, may also have  two completely different colors in the same eye.

 

Did you know? An ancient Native American legend has it that dogs who have two different colored eyes have”ghost eyes” because the dog can see Heaven with the blue eye and earth with the brown eye at the same time.

 

References:

  • American Kennel Club: Siberian Husky Breed Standard
  • Pet Education: Heterochromia: Eyes of Different Colors in Dog by Race Foster DVM

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