Dogs with two different eye colors have one eye of a color and the other one of another.
These dogs aren't really rare or unusual per se', but we can't deny that they can be quite intriguing looking dogs!
One may wonder if there are any problems with these eyes, but generally there's nothing wrong with the eyes of these fellows other than just being different.
Certain dog breeds though are more prone than others to develop two eyes of different colors.
Today we'll discover exactly how dogs develop two different colored eyes and what breeds are mostly affected.
The Effect of Melanin
While the majority of dogs have dark brown eyes, some can also have amber eyes, copper eyes and blue eyes. What gives dogs eyes though their different colors?
Melanin is the pigment that gives color to a dog's eyes, coat and skin. The color of a dog's eyes depends on the concentration of melanin found in the dog's iris, the pigmented structure surrounding the dog's pupil.
The more concentrated the melanin, the darker the eyes will be.
When dogs present with eyes of different colors, the concentration of melanin differs between the eyes, therefore, it is not distributed uniformly.
So for example, in a dog with a blue eye and a brown one, the brown eye has a higher concentration of melanin, while the blue one will have considerably less.
The phenomenon of dogs having two different eye colors is scientifically known as "complete heterochromia iridis. " Some breeders though like to refer to it as simply being "bi-eyed."
A Matter of Genes
The phenomenon of having eyes of two different colors is mostly because of genetics. In other words, it's a trait that can be passed down from one generation to the next.
As mentioned, certain dog breeds are more likely to develop this trait compared to others.
The underlying cause of heterochromia in dogs has yet to be confirmed, but scientific consensus seems to agree that there must be a genetic issue at play. There is therefore belief that it stems as a result of lack of genetic diversity.
In particular, there seems to be a mutation with the genes responsible for distributing melanin.
In particular, complete heterochromia may be seen with a certain frequency in dog breeds with the merle coat.
As appealing as having two colored eyes can be though, in certain dogs breeds it's frowned upon and considered a fault in the show ring.
Did you know? Aristotle was aware of the phenomenon of having two different eye colors and called it "heteroglaucos."
Dog Breeds With Two Different Colored Eyes
These dog breeds are known for being predisposed to heterochromia. They can therefore present with two eyes of different colors.
- Siberian husky: we are used to seeing these dogs with blue eyes, but some fellows can have a blue eye and a brown one. This is acceptable in the American Kennel Club's standard; indeed the standard states "eyes may be brown or blue in color; one of each or parti-colored. "
- Australian shepherd: as with the Siberian husky, at times one may stumble on an Aussie with two colored eyes. According to the United States Australian Shepherd Association, Australian shepherds that boast a blue or red merle coat may sometimes have a blue eye and a brown eye.
- Louisiana Catahoula leopard dogs: this all American dog breed which sports intriguing looking coats, may also sometimes sport intriguing looking eyes of a different color.
- Border collies. Heterochromia occasionally shows up in some border collies and some some potential dog owners may be put off by the looks. Namely, a border collie named Molly was supposedly abandoned due to her different colored eyes, but fortunately, she later found a good permanent home.
- Dalmatians: you may not see complete heterochromia in this bred too often, but it is seems to pop up now and then in this breed.
- Dachshunds. Two differently colored eyes may be seen in doxies that have merle coats (dapple).
Possible Eye Problems
There is a reason why in the introduction we said "generally" there is nothing wrong with dogs with two eyes of different colors.
The word generally is in italics because there are sometimes exceptions to the rule. In this case though, the eyes generally aren't of different colors to start with.
Sometimes dog owners may notice how one of their dog's eyes start assuming a bluish tint or a cloudy look. When this happens, it's important to report these changes to the vet.
Medical conditions affecting the eye that may cause color changes or changes to the appearance of the eye include cataracts, nuclear sclerosis, glaucoma, anterior uveitis and corneal dystrophy.
These are eye disorders that are known to possibly cause blue eyes in dogs, explains veterinarian Dr. Becker.
Other Types of Heterochromia
As discussed earlier, complete heterochromia is having one eye color that is different from the other, but many may not be aware that there is another form of heterochromia in dogs known as "sectoral heterochromia iridis."
In this case, within one eye, there is one color that is of a completely different color from the rest of the eye. This can sometimes be seen in the Australian shepherd, border collie, Welsh corgi, Catahoula cur and great dane.
It can also be found in other dog breeds that are known to also have the merle trait. An exception is the Siberian husky, which does not carry the merle trait but that may at times sport two different colors within the same eye.
Did you know? According to an ancient Native American legend dogs who had two different colored eyes were known as having "ghost eyes" because they were capable of seeing simultaneously heaven with the blue eye and earth with the brown eye.
- American Kennel Club: Siberian Husky Breed Standard, retrieved from the web on May 14h, 2016
- Pet Education: Heterochromia: Eyes of Different Colors in Dog by Race Foster DVM
- Common Clinical Presentations in Dogs and Cats By Ryane E. Englar, retrieved from the web on May 14th, 2016