We’ve all seen a Blue Merle Aussie before. They are one of the most coveted colors with their unique dappled coat and, what they’re possibly most well known for, their stunning blue eyes.
With this color being so desirable, it can seem like all Australian Shepherds have blue eyes, but is that always the case?
The short answer is no. Not all Blue Merle Aussies have blue eyes. However, it is prevalent. The blue merle color and pattern are caused by a gene that varies the amount of pigment in the hair, skin, and eyes. This often causes Australian Shepherds to be born with blue eyes.
Now let’s get into all the details regarding these famous blue eyes. To understand them you’ll first need to know what colors Aussies come in, how the merle gene works, and how to breed for it.
What Colors do Australian Shepherds Come In?
Australian Shepherds officially come in four colors: black, blue merle, red, and red merle. They are bred in other colors, but they need to be one of those four colors for official breed-sanctioned events.
While Australian Shepherds are most well known for their merle coats and stunning blue eyes, those aren’t the only colors they come in. According to the American Kennel Club, Australian Shepherds come in four colors: black, blue merle, red, and red merle.
However, if you’re interested in the genetic aspect of the colors, they really only come in two: black and red. Blue merle and red merle are simply the dilute forms of the black and red colors.
Keep in mind that Australian Shepherds are traditionally working dogs, and frequently they’re bred without much regard for their coloration. They are instead bred for temperament and working ability. So, if you’re looking at a working line of Aussies, you’ll usually see a lot more colors, including tri colors and various shades of brown.
The one color you don’t want to see in an Australian Shepherd is white, which is associated with a double dose of the merle gene.
Dogs with a double dose of this gene are often born deaf and blind with several other disabilities. Most puppies with a double dose are born dead.
How Does The Merle Gene Work?
The merle gene works by causing a variation in pigment in the hair and skin cells. This creates the mottled pattern that merle dogs are so well known for. It’s technically a dilution gene meaning that it lightens the intensity of other pigments. It simply does it in an uneven pattern.
To understand how the merle gene works, you must first understand how dilution works. For example, think about a blue Pitbull. These dogs are considered very desirable because of their silvery grey color. However, it is not considered an official color. That’s because it’s not blue. It’s just a diluted black.
In the show ring, dilutes are often undesirable because the gene can be unpredictable. It is also hard to standardize a diluted color because every dog will come out differently.
In the case of black dogs, they will have the gene to be black, but they will also carry a gene that dilutes that pigmentation and makes the expression weaker. So instead of having a black dog, you’ll have a dog that’s closer to grey.
The dilution gene works similarly in merle dogs, but it only affects patches instead of affecting the whole dog. That’s why if you look at a blue merle dog, which is really a black dog with the merle dilution gene, you’ll notice that while much of the dog is a slate blue, there are still some patches of black.
These darker patches are where the dilution isn’t as strong, so you can see the original color of the dog if the dilution gene wasn’t present.
In addition to affecting the pigment in the skin and coat, the merle gene, and dilution genes in general, can affect the color of the eyes. That’s why merle dogs are often seen with blue or green colored eyes instead of the typical brown. The normal brown pigmentation is simply not present.
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Does The Merle Gene Always Cause Blue Eyes for Australian Shepherds?
No, the merle gene does not always cause blue eyes. The merle gene causes the lightening of pigment in patches throughout the body. If these patches do not coincide with the eyes, the dog will have brown eyes instead. They may also have multicolored eyes.
When you’re breeding a blue merle dog of any breed, blue eyes are generally considered the most desirable. However, they are not guaranteed, and because of the way the merle gene works, there is no real way to breed for them.
The merle gene causes random patches of lightened pigment throughout the dog’s body. If these patches of lightened pigment go over the eyes, then the eyes will lack pigment as well and appear blue. If the eyes are not located in a dilute area, they will remain brown.
The merle gene works randomly and can even change slightly throughout the dog’s life, so there is no real way to breed for blue eyes. Even if both parents have blue eyes, the puppy may not.
In other colors, you can breed for eye color, and the puppy’s eye color is most likely to match the color of the parents’ eyes.
However, with the merle gene, you simply cannot do that. It is so random that the eyes won’t even be the same color a lot of the time.
One eye could be brown and one blue or the dog could even have patches of both colors within the same eye. With the merle gene, you never know what you’re going to get.
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Are There Risks Associated With The Merle Gene?
When you’re breeding a dog with a dilute gene, such as the merle gene, and you want to pass it on to the puppies, it makes the most sense to breed two dogs with the same gene expression, right? Unfortunately, in the case of merle dogs, breeding two dogs together that express the merle gene can have very dangerous consequences.
If a puppy receives two doses of the merle gene, they are known as a fatal white. They will typically die before birth, and if they manage to survive, they’ll live with severe defects for the rest of their life. They generally are primarily white with glassy blue eyes.
For a healthy merle dog, you want the dog to have only one dose of the merle gene. That will allow the gene to be expressed without suffering any health consequences.
That’s why when breeding for merles. It’s best to breed a merle dog with a dog that does not carry the merle gene.
You’ll get fewer merle puppies that way, but you’ll also reduce the risk of producing fatal whites. Fatal white dogs are typically blind and deaf and usually suffer from neurological conditions if they survive past birth.
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While blue merle Australian Shepherds are often associated with blue eyes, not all have blue eyes.
The mottled pattern and blue eyes are caused by a dilution gene that only affects their body in patches. If these patches do not fall over the eyes, the eyes will appear brown instead of blue.
There is no way to breed a merle dog specifically for blue eyes, and you should always avoid breeding two merle dogs together. Although this will produce more blue-eyed puppies, it will also produce puppies with a double dose of the merle gene, which is typically fatal.