Let’s take a look into concerns regarding blue eyed horses and health issues. Most horses are born with dark brown eyes but colors can include a range of amber, blue, hazel and green hues. Blue eyes in horses are typically associated with pale cream colored coats but, as with the horse in the photo above, horses with brown coats can also have blue eyes. One can understand how myths and legends could form surrounding something as simple as a blue eyed horse since they are not common and may seem strikingly unusual.
One of the myths of Blue eyed horses is that they have bad eyesight. Fact is Equine vision problems do not necessarily coincide with blue eyes. Blue eyed horses can have excellent vision. The likely connection to equine vision problems, may lie with coat coloring, not eye color.
A “Blue” eye actually has a blue iris. The iris is the colored part of the inside of the eye surrounding the pupil. While humans have an astonishing number of normal iris colors (from blue to green to brown to violet), horses typically have one of two: blue or brown. Some horses have irises that are both brown and blue; the medical term for a two-colored iris is “heterochromiairidis.” These are more common in horses with patterned coats such as Paints and Appaloosas. Blue irises are usually seen in horses with light-colored coats such as cremellos. Having a blue iris, however,does not make a horse any more likely to have intraocular problems, including equine recurrent uveitis.
Coat color, on the other hand, can be associated with eye problems. For instance, leopard Appaloosas are more likely to have difficulty seeing in the dark (if affected by a condition called stationary congenital night blindness), and chocolate-colored Rocky Mountain Horses are more likely to have multiple intraocular abnormalities, including blinding conditions such as retinal detachment. In these cases genetics are responsible for the relationship between breed, coat color, and eye diseases.
While having a blue iris might not make a horse more likely to have an eye disease, blue irises usually go hand in hand with pink skin. One of the most important known risk factors for developing squamous cell carcinoma (SCC, a form of skin cancer) is pink skin. Thus, horses with pink eyelids are more likely to get SCC. No relationship has been documented, however, between blue irises and SCC. Protect a horse with pink eyelids or excessive white on his face from ultraviolet (UV) light exposure with a UV-blocking fly mask.
Assessing what a horse can (and can’t) see is extremely challenging for horse owners. While there is a lot of information out there on equine eye disease, ultimately,the best source of information about any eye disease is your veterinarian or veterinary ophthalmologist.