Why do Some Horses Have Blue Eyes?
Although humans display a variety of eye colors and shades, horses are usually limited to two colors — brown and blue.
Of the two, brown is the more prevalent, while blue is the result of a gene, the double-dilute cream gene, which when present in a horse, it’s responsible for their blue eyes.
Even though blue-eyed horses are beautiful and unique, some view them with skepticism, fear or even prejudice. In terms of resale potential, they’re often a wild card.
There are several reasons why these horses are somewhat discriminated against. Beliefs according to which they have more temperamental issues, more health problems than their brown-eyed peers, or that they’re simply trouble don’t help their cause either.
Below, I’m going to address some of these beliefs and examine why some horses are more likely to have blue eyes than others.
Horse Breeds with Blue Eyes
There isn’t a specific horse breed that has blue eyes, yet in some horse breeds, blue eyes are more prevalent than in others.
Because there’s a correlation between coat color and blue eyes, horses with lighter coat colors are more likely to have blue eyes than horses with a dark coat color.
This doesn’t mean that dark-coated horses will never produce blue-eye offspring. Blue eyes have been noticed even in brown, chestnut and palomino horses. But it’s exceedingly rare compared to other breeds.
When a horse has two copies of the creme gene, we have a double dilution creme gene that ‘dilutes’ the horse’s skin pigmentation, causing pink skin and blue eyes.
Cremellos and perlinos are prime examples of horses whose double diluted creme gene results in blue eyes.
I mentioned how brown, chestnut and palomino horses can also sometimes produce blue eyes. But this usually only happens if the horse has white markings or white spots.
You’ll often see blue eyes on paints, pintos even without the double dilute gene. But they all usually have white faces.
Other notable breeds that have blue eyes are overos. These too have different white markings, and because the pigmentation in their iris is less dense, they produce blue eyes.
Therefore, there isn’t a single horse breed with characteristically blue eyes, but breeds like paints, pintos, cremellos, perlinos and overos will produce blue eyes more often than other breeds.
Are Blue-Eyed Horses Rare?
When it comes to the general horse population, blue eyes are just not something that you’ll commonly see, especially not in dark coated horses. It’s not that it’s impossible, but it’s not as likely as in light-skinned horses.
Therefore, popular breeds like Arabians, Morgans or Thoroughbreds don’t routinely produce blue eyes.
On the other hand, pintos, cremellos, perlinos and paints are much more likely to have blue eyes because of the double dilute cream gene.
The Blue-Eyed Horse Tracking Registry keeps tabs on blue-eyed horses. Horses with one or both eyes are eligible for registration. And any shade of blue is accepted, even when mixed with other colors, provided that the blue is easily identified in a photo.
Therefore, blue-eyed horses are rare in the general horse population and more common in certain breeds.
Although there hasn’t been a study to estimate the percentage of blue-eyed horses relative to the horse population, it’s safe to assume that it’s lower than the percentage of blue-eyed humans relative to the whole population, which is at around 8-10%.
Rare and unique, blue-eyed horses aren’t as hot a commodity in the equine world as one would think. That’s because there are a lot of misconceptions related to their personalities and health.
Many people wrongly believe that these horses have more health issues or that they have behavioral problems because they think they’re more sensitive to light.
As I will explain below, neither of these beliefs are anchored in reality or based on any evidence.
Do Horses with Blue Eyes Live Less?
Besides the other misconceptions associated with blue-eyed horses (e.g. That they’re more temperamental — they’re not.), an often-mentioned objection towards these horses is the belief that they may live less than their brown-eyed peers.
There’s no study to prove that blue-eyed horses live less than brown-eyed horses, nor that they get sick more often or whether they’re generally more prone to diseases. There’s also no proven link or correlation between eye color and health status.
But there is a study conducted by the University of Illinois Veterinary Teaching Hospital that compared the medical records of brown-eyed horses to the medical records of blue-eyed horses and found that blue-eyed horses aren’t more likely to get diseases of the eye or eye socket than brown-eyed horses.
Therefore, blue-eyed horses aren’t more likely to have vision problems or have cataracts, recurrent uveitis, glaucoma, intraocular neoplasia, orbital cellulitis, and orbital neoplasia compared to brown-eyed horses.
Although we can’t extrapolate from this to other diseases, not related to the eye, it’s safe to assume that since the only difference between these horses is their eye color, we can’t conclude that eye color is linked to longevity or health status in any way.
Still, there is one disease that is indeed more prevalent in blue-eyed horses — SCC (squamous cell carcinoma). But this too isn’t linked to the color of the iris, but it’s linked to the skin pigmentation of blue-eyed horses.
Problems of Blue Eyed Horses
The same University study I mentioned has found that blue-eyed horses are more likely to get squamous cell carcinoma (SCC), but not because of their eye color, but because of the skin pigmentation around the eye and eyelid.
SCC is more prevalent generally in fair-skinned horses, so this again isn’t something that’s intrinsically linked to eye color.
Although it’s best to protect all horses from the harmful effects of UV rays, fair-skinned horses require a stronger level of protection to ward off the harmful effects of UV rays.
Luckily, there are ways to keep your fair-skinned horse safe and reduce the incidence of SCC.
The most common methods you can deploy to protect your horse from harmful UV rays include natural shade provided by trees and woods, the use of fly masks, and the use of sunscreen.
Fly masks can offer protection to the skin around the eyes and the face of your horse including the ears.
Make sure to invest in fly masks that are rated for UV protection and always choose ones with the highest UV rating.
Alternatively, zinc oxide sunscreen lotion applied daily and even simple things like providing enough shade for your horses to take cover during periods of the day with strong sunlight can go a long way in keeping your horse safe from harmful sun exposure.
It’s important to do your best in preventing SCC, because it’s an aggressive and difficult to treat cancer type, so prevention is your best bet against it.
All fair-skinned horses must be protected from this disease, not only blue-eyed ones, since all horses with pink skin are more susceptible to getting SCC.
To sum up, even though blue-eyed horses are more likely to get SCC, this isn’t because of their eye color. In addition, blue-eyed horses don’t present other health problems or behavioral challenges compared to dark-eyed horses.
If you like blue-eyed horses, don’t be afraid to own one. You’ll see that other than their eye color, they’re no different from horses with dark eyes.
Horse with One Blue and One Brown Eye
Horses with just one blue eye are also eligible for registration in the Blue Eyed Horse Tracking Registry since they still qualify as blue-eyed horses.
Horses with one blue and one brown eye have different amounts of pigments in each eye. This is something that’s noticeable in humans as well, and it’s not limited to horses or humans alone. Dogs and cats can also have different colored eyes.
A different level of pigmentation in the iris of the eyes causes the difference in eye color and the scientific name for this is heterochromia.
When one eye is blue, the other brown, you have a horse with complete heterochromia. When different segments of the same eye are different colors, you have a horse with segmental heterochromia.
Neither horses with one blue eye, nor those with both blue eyes are more prone to diseases or vision problems than horses with brown eyes.
A simple gene variation, the presence of the double dilute creme gene, is responsible for blue eyes in horses. Horses can have both eyes blue or only one of their eyes blue.
Just because a horse is blue-eyed, it doesn’t mean it’s more temperamental, more sensitive to light, susceptible to diseases or that it can have a shorter lifespan.
The only disease that’s more prevalent in horses with blue eyes is squamous cell carcinoma, but that’s prevalent in all light skinned horses, not just the ones with blue eyes.
Although the exact percentage of horses with blue eyes is not known, they’re a rare occurrence across the general horse population, but more common in pintos, paints, cremellos, and perlinos.