Horses have captivating eyes. Their eyes display a spectrum of colors, each with a unique appearance. These variations add to each animal’s individuality and beauty. Exploring equine eye colors reveals their unique distinctions.
Common Equine Eye Hues
The most frequently observed eye colors in horses are various shades of brown. These range from a deep, almost black hue to lighter, warm brown tones. The intensity of the brown can vary widely, often appearing dark and rich. These brown eyes are considered the standard and are seen across the vast majority of horse breeds worldwide.
Pigmentation in the iris primarily determines these common eye colors. Horses with dark brown eyes have a high concentration of melanin within the iris. Lighter brown eyes indicate a slightly lower, but still significant, amount of this pigment.
Distinctive and Rare Eye Colors
Beyond common brown, horses can display several distinctive and less common eye colors. Blue eyes are perhaps the most recognized, often appearing a clear, pale blue similar to human blue eyes. Sometimes, a horse might have one blue eye and one brown eye, a condition called heterochromia or “wall eye” or “glass eye.” This striking appearance occurs when pigmentation differs between the two irises.
Amber eyes are yellowish-brown or golden, with noticeable yellow undertones. Green eyes are rarer and appear as a blend of yellow and blue pigments, sometimes with brown flecks. Hazel eyes are uncommon, characterized by a mix of brown and green or yellow, often with multiple color flecks.
The Genetics Behind Eye Color
The array of eye colors observed in horses is influenced by genetic factors, particularly dilution genes that affect pigment production. The Cream gene, for instance, is a dilution gene that can lighten both coat and eye color. A single copy can lighten brown eyes to amber or hazel, while two copies can result in blue eyes, especially in horses with palomino or cremello coat colors.
The Champagne gene causes dilution, leading to amber eyes in horses with a chestnut base coat or green eyes in those with a bay base. This gene affects how pigment is displayed, often giving the iris a glassy or translucent appearance. The Pearl gene, another dilution gene, can produce lighter eyes, including amber or even blue, particularly when combined with other dilution genes like Cream.
Genes responsible for white spotting patterns, such as the Splashed White gene, can influence eye color. These genes are often associated with blue eyes, especially when white markings extend to the face and around the eyes. Heterochromia, where a horse has two different colored eyes, often results from incomplete pigment distribution in the iris, linked to these same white spotting genes. The Silver Dapple gene, while primarily affecting black pigment in the coat, can sometimes lighten brown eyes to a lighter amber or yellowish shade.