By Tamara McRill
Ever spot a pair of demonically glowing green or red eyes in the dark, only to realize they belong to your cute and cuddly dog? What really gets to me is when I’m the one outside and I see the floating bright orbs peering out my window. You know, it’s that split second where you’re torn between wanting to turn and run or bust in to save your pets from…whatever “It” is.
But of course, “It” is your dog’s (or even cat’s) eyes glowing in the dark. It turns out there is even a very scientific – and reassuring – reason their eyes shine so eerily in the darkness.
No, that’s not the starting phrase of an exorcism, although it is Latin. It means “bright tapestry.” The words are also the scientific term for the light-reflecting surface between a dog’s optic nerve and retina.
The tapetum lucidum is what makes dog’s eyes react to light exposure differently than human eyes, essentially reflecting the light back through their eyes like a mirror. The rods and cones make use of the multiplied light to see better in the dark. Dogs and other animals with the structure, like cats and deer, can use very low levels of light to see.
In addition to superior night vision, this reflected light is also what produces eyeshine in dogs…that surreal colored glow that comes out in their eyes at night. What I find fascinating is that not every dog’s eyeshine is the same color.
My chocolate lab, Wuppy, has brown eyes that have a predominant phosphorus green eyeshine. One of our mixed breed dogs, Cody, has one blue eye and one brown eye. His eyes glow a dark red when hit with light in the dark, although the blue eye is more intense.
The colors of a dog’s eyeshine aren’t limited to red and green, either. They can be all shades of blue, orange, yellow, turquoise or even violet. The specific color reflected depends on the amount of zinc or riboflavin in the eye cells.
Red glowing eyes at night are the result of blood vessels reflecting light. This is common with white dogs who have blue eyes.
Some dog breeds are known for certain eyeshine color, although the tendency isn’t a guarantee that’s the color they’ll have. Yellow labs tend to have a light yellow shine, and black labs a deep yellow or green. Miniature Schnauzers are known for turquoise glow.
Outside Influences on Color
The eyeshine color can also depend on other factors, such as the kind of light being shined in a dog’s eyes. Headlights, halogen lights, flashlights and lights with colored filters may all produce a different glow in the eyes of the same dog. The intensity of the light is also a factor, as is the distance between the light source and the dog, and where you are standing in relation to the dog’s location.
I have photos of Wuppy where his eyes glow green. But in other photos, all taken during the same nighttime romp, the colors range from red and orange, to yellow.
You can often tell eyeshine color by taking a photo of your dog with the flash on, with them looking up at you. Just try not to get them right in the eye with the flash. If your dog is younger than 16 weeks, their tapetum will probably be blue or violet. The color of their glow may change as they get older.
What color do your pet’s eyes glow in the dark?
Photos by Tamara McRill
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