It's safe to say that our canine friends perceive the world in a different way than we do. For one thing, their noses are at least 1,000 times more effective as ours, giving them an incredibly powerful sense of smell. Their hearing is often keener as well.
Sight is one area where dogs don't have the upper hand. Our canine companions see the world very differently than we do, and it turns out that the human eye is much more adept when it comes to seeing colors and differentiating between them.
But what’s the truth: Are dogs color blind, seeing the world only in black, white, and shades of gray? Or do they see color in some way or another?
Are Dogs Actually Color Blind?
Your dog's color vision isn't as good as yours, but they are not completely color blind.
Many people believe that dogs are fully color blind, seeing everything only in shades of black and white. This urban myth originated from early writings and research from the 1930s that hypothesized that dogs were color blind and their color perception only allowed them to see various shades of gray. The myth spread from there. You'll still find many people who will tell you that dogs only see in black and white.
As time went on, it became clear that this wasn't the case. Advancing study in the world of ophthalmology revealed that a dog's eyes work in similar fashion to those of a human, and that dogs actually can perceive some color. In fact, dogs probably see the world much like a person with color blindness does — certain colors aren't vivid, some colors are seen better than others, and different hues of the same color are hard to differentiate between.
How Your Dog's Eyes Work
Your dog's eyes have many of the same components that your eyes do. All things considered, your canine friend's eyes work in the same way the human eye does.
The optic nerve
The optic nerve is the backbone of your dog's eye function. It connects the eyeball and the brain, and it carries electrical impulses from the eye to the brain, where those signals are processed to form an image.
Just like you, your dog's eyes have a retina. This is the innermost lining of the eyeball, and it functions to receive light and send those signals to the brain via the optic nerve, where the information is processed to form sight.
Inside of the retina, millions of light-sensing cells (called photoreceptor cells) help to process light coming into the eye and transform it into an image. Rods are one type of photoreceptor cell. They are sensitive cells that work mostly to catch movement, and they also help your dog see in low-light situations.
Cones are another type of light-sensing cell in your dog's retina, and they're the ones largely responsible for your dog's color vision. Where rods work in low light, cones work in bright light. They're also helpful for making out fine detail.
Where’s the Difference?
So, if all of these components of your dog's eyes work in a similar fashion to the human eye, why do dogs always experience some level of color blindness and humans do not? The answer lies in the cones.
Our eyes are referred to as trichromatic. This means that humans (and a few other types of primates) have three types of cones in the eye. Each one of these three types of cones function to let us see different colors on the spectrum — blue, red, and green.
Dogs are dichromatic, so they only have two types of cones in the eye. One functions to see blues, and the other sees shades in between a human's version of red and green. Essentially, dogs are missing red-green cones in their eyes, resulting in a form of red-green color blindness. This is the same reason that color-blind humans don't see certain colors — they're missing red-green cones.
What About Night Vision?
Can dogs see clearly in the dark?
Even though dogs might not see color as strongly as we do, they tend to see a lot better than a human in the dark. While dogs don't exactly have perfect night vision, seeing well in the dark is one area where your dog's vision outshines yours.
Dogs have good night vision because it's part of their evolutionary makeup. The ancient wild canines that our modern-day dogs evolved from used to hunt mostly at dusk and dawn. So, they needed to be able to see well in low light in order to track their prey. This trait has been passed down over generations and still affects dog vision today.
Anatomically, the canine eye has specific features that help them see well in the dark. First, their pupils are larger and allow more light into the eye, even when light is at a premium. Dog eyes also have many more rods in them than the human eye does — remember, rod cells help to see in low light, while cone cells are more helpful for bright light. Since rods also help to catch movement, the canine eye is also better than a human's when it comes to seeing things move, especially at a distance.
More than any other feature, though, something called the tapetum lucidum gives dogs their unique ability to see well when it's dark. It acts as a reflector behind the retina, reflecting back the light that has already entered the eye, and gives the retina another opportunity to process that light. Basically, your dog's eyes get a boost at night thanks to this part of the eyeball. This double reflection is also the reason that your pet's eyes sometimes appear to glow at night.
How Your Dog Sees Color
We've seen that your dog's vision isn't all that different from yours. They don't see as many hues in the color spectrum, but they're quite good at picking up movement and at seeing in dim light. So, what exactly does your pooch see when he ventures out on his afternoon walk?
Dogs' eyes are best at picking up shades of yellow, blue, and green. When these colors are combined as they eye takes them in, your dog's brain translates them into mostly dark and light yellow, grayish yellows and grayish browns, and dark blue and light blue. Your dog doesn't see a lot of green and red shades.
Ever wonder why your pooch loves chasing yellow tennis balls across the yard? Fido probably sees the ball pretty well, especially against the green grass which comes across as rather dull, and his eyes are very adept at picking up fast movement. Of course, he also just loves playing fetch!
See Through New Eyes
Your dog is not color blind, contrary to popular belief. While they do see a lot of dull, brownish-yellow gray shades and various shades of blue, their world doesn't appear to them entirely in black, gray, and white.
Dogs see color, just not in quite the same way that we do. And remember: Thanks to your dog's impeccable sense of smell and taste, their perception of their environment is in no way limited. Next time you take your canine companion on a walk outdoors, try to imagine the world through their eyes.