Why Do Australian Shepherds Have Blue Eyes?
The Australian Shepherd, affectionately known as the “Aussie”, is known not only for its intelligence, loving personality, and agility, but also for its captivating eyes – which can be a stunning blue.
So, what gives the Australian Shepherd its unique eye color? And what does it imply about its health and genetics?
We’re here to give you these answers and more.
What Is the Blue Color?
You might be surprised to learn that blue eyes are not in fact blue. Rather, they are eyes with low pigmentation, which causes light to scatter in the eye and appear as blue when seen.
This concept is similar to why the sky appears blue: when sunlight hits gases in the sky and scatters, we see the blue light first and most prominently, because it has the lowest wavelength and carries most easily.
So when you see blue eyes, keep that in mind: the eyes are in fact just low-pigmentation, and not actually the color blue.
What Causes Blue Eyes?
The main factor leading to the blue color of Australian Shepherd eyes is genetics. Specifically, the Merle gene is what typically causes patches of low pigmentation – in fur or eyes.
On the skin of an Aussie, this can be seen as white patches which gives some Aussies a distinctive “patchy” look. The same Merle gene which dilutes the coat color also reduces pigmentation in the eye – in one eye, or both eyes.
While the Merle gene significantly affects the likelihood of blue eyes, it’s not the only gene that contributes to blue eyes. Other genes are continuing to be discovered which influence blue eyes in Aussies and other dog breeds. For this reason, you may see non-Merle Aussies with blue eyes.
Why Can An Aussie's Eyes Be Different Colors?
The phenomenon where a dog (or a person) has differently colored eyes is called heterochromia.
When pigments are expressed in a given region of the body, different genes may be expressed. It’s for this reason that a Merle Australian Shepherd won’t be entirely white, but rather have patches of white, brown, black, etc. This depends on what genes are expressed in that patch of skin.
It’s the same story for the eyes. One eye can have the light-pigmentation genes expressed, while the other eye doesn’t express those genes. This leads to one eye being blue, and the other being a different color like brown.
Do All Aussies Have Blue Eyes?
No. While the trait is common in the breed, and often associated with Australian Shepherds, Aussies can have blue, green, hazel, yellow, and brown eyes. The eyes can be solidly one color, or have flickering of other colors too.
Are Blue Eyes a Sign of Bad Health?
Blue eyes on their own are not a sign of poor health. However, blue eyes may stem from the Merle gene which is linked to genetic health issues like deafness. So, is this something you should be worried about?
If an Aussie carries the Merle gene, they may carry a single or double allele (i.e. one or two copies of the Merle gene). The presence of the Merle gene can lead to blue eyes, even if only a single allele is present. It’s a dominant gene.
One Merle gene typically doesn’t cause health issues. But having two Merle genes – also called being “double Merle” – can lead to genetic health issues, typically hearing and vision issues. This can result from breeding two Merle-patterned Aussies, which can result in offspring that carry two copies of the Merle gene.
So, while blue eyes aren’t a sign of bad health, they can be a sign of the Merle gene. And if both parents are Merle, there’s a possibility that the offspring is “double Merle” and will have health issues.
The Australian Shepherd is a loving family companion that is also excellent with kids. But what typically stands out about them visually is their fur pattern and eye colors. Specifically, many Aussies sport patterned fur and blue eyes.
The blue eye of the Australian Shepherd can be caused by the Merle gene, but can result from other genetic factors as well, which continue to be studied.
The genes can be expressed in one or both eyes, resulting in one or both eyes being blue. Additionally, while the Merle gene is not necessarily dangerous, two copies of it can cause health issues – so it’s best to avoid breeding two Merle Australian Shepherds, as their offspring may carry two copies of the Merle gene and have health issues.
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