Universally known as lovable and wildly endearing, dogs have become almost synonymous with loyalty, playfulness, and friendliness.
They have a popular reputation for being “man’s best friend” for all the previous reasons and more. However, many people don’t know that dogs can’t see things the way humans do. We mean this in a very literal sense.
Here’s a good question that’s often asked: “Do dogs see color?”
How Dogs See Color
Dogs’ brains have a smaller number of neurons that process visual information when compared to humans. Naturally, their dominant sense is smell, followed by hearing, and then followed by sight.
We know dogs can learn up to 165 words, according to the American Psychological Association. But do dogs see color?
Shortly put, yes and no.
Dogs can see color, but they have a very limited palette to work with. The colors they can see aren’t as varied or as rich as the colors humans can see.
This is further demonstrated by studies that have shown that dogs have dichromatic color vision.
Both the eyes of humans and dogs have cells called cones. Cones are photoreceptors that are primarily responsible for color vision. While humans have three color-sensitive cone cells, dogs only have two.
Cones are critical concerning color vision. In fact, color blindness is caused when a person is missing one of these cones.
This loss manifests in a person’s sight. Instead of being able to see a varied range of color, a person often can’t differentiate between certain colors based on hue alone. This is similar in the case of dogs.
Having limited cones, dogs can see colors like red or green, but can’t tell them apart based only on their color. This is because the two cone cells dogs have are yellow and blue.
Dogs perceive red, green, and yellow as one color. They also see blue and violet as one hue, and they see other colors like magenta as grey. Put another way, dogs have red-green color blindness.
To gain a better sense of a dog’s color vision, think of it as a much more muted version of a human’s.
Brightness discrimination is the ability to tell apart different levels of brightness. Moreover, it’s the ability to differentiate between separate hues.
In dogs, the brightness discrimination is two times worse than it is in humans.
This means that shades of grey that are seen as different by humans are seen as the same color by dogs. Accordingly, dogs can’t tell apart colors that humans can easily differentiate between.
Visual acuity refers to the spatial resolution of the eye. Simply put, it’s the measure by which an eye can distinguish shapes at a certain distance.
A dog’s visual acuity is 4 to 8 times worse than a human’s. Accordingly, dogs are near-sighted.
While a human with perfect vision has 20/20 eyesight, dogs typically have 20/75 vision. This means that while a human needs to stand 75 feet away from an object to clearly distinguish it, a dog needs to stand 20 feet away.
However, there are exceptions. One example are Labradors. Labradors are often guide dogs, or “seeing-eye” dogs. This isn’t only because of their good temperament, but also because they may have vision closer to 20/20 since they’re bred for better eyesight.
The position of a dog’s eyes and how they’re set also determines their field of view and peripheral vision. While humans’ eyes are set close together and are straightforward, dogs’ eyes are typically set at a 20-degree angle.
Naturally, this widens a dog’s peripheral vision dramatically and aids them in activities such as leaping and catching. This would have helped dogs as hunters in their past when they were more on their own. This wide-set eyesight would have allowed them to track prey much better.
Can Dogs Tell Colors Apart?
Dogs can see colors such as green or red, but based on their color alone they can’t tell them apart. However, if there’s a difference in the perceived brightness, then they can tell them apart.
In this case, dogs depend on contrast and brightness to help them differentiate between colors.
For example, to be able to tell the difference between yellow and red at a traffic light, dogs depend on other visual and sensory cues.
These cues range from certain smells and position of the light to oncoming car or traffic noise. Such details communicate to a dog when it becomes safe to cross the street.
However, a feature of dogs’ vision is the fact that dogs have more rod cells than humans.
Rod cells are photoreceptors present in the eye that are responsible for night vision. They’re seen in shades of black, grey, and white. This is why dogs see well at night.
Rod cells are also responsible for detecting objects in motion.
This compensates for dogs’ limited visual acuity. So while they might not notice you standing far away, they’ll be able to distinguish you through your movement.
This is also how dogs recognize owners. They’re able to tell them apart through smell or motion, especially when they attribute a particular motion to said owner.
So while it might seem upsetting that dogs have limited options when it comes to seeing color, they don’t depend on sight to navigate the world around them.
In fact, dogs are brilliant and can react to subtle facial expressions. They also can pick up on physical cues.
This is why dog trainers advise to use physical gestures rather than words. These lovable pets understand the language of the body easily.
What Diseases Can Alter A Dog’s Eyesight?
As a veterinarian, there are a number of diseases I’ve seen in my patients that have affected their vision:
- Congenital Cataracts can be seen in some breeds from a very young age. Breeds that can be affected include
- Acquired Cataracts can happen spontaneously or as a result of diabetes.
- Progressive Retinal Atrophy is a degenerative disease in which the blood vessels that supply the retina of the eye begin to shrink. This causes a lack of blood flow to the photoreceptors of the eye and gradually diminishes the vision of the dog.
- Glaucoma is a disease where the pressure inside the eyeball increases above normal. Too much pressure causes pain and ultimately destroys the retina of the eye rending the dog permanently blind.
- Pannus is an inflammatory disease of the eye caused by excessive exposure to UV light. Here in Colorado we see quite a bit of this disease due to the higher elevations.
- Pigmentary Keratitis is a disease of the cornea that usually occurs secondary to some type of chronic irritation. Many brachycephalic dogs can be prone to this whether it’s because their eyes “bug” out so much that they are chronically irritated, or they have another condition that irritates the eye (such as dry eye or entropion).
Can Anything Be Done To Improve A Dog’s Vision?
Are you asking if there are special glasses that could help a dog see color where they can’t before? No. There’s not.
There’s also not a way to have them wear glasses so that they can see more clearly. You can’t give them improved functionality when they lack some of the basic anatomy that provides human-grade vision.
If there’s a disease that’s blocking vision, then that’s what can be treated. Cataracts can be removed and the lens replaced with an artificial one that lets light back into the eye and restores vision. Corneal diseases can be treated to clear the pigmentation and allow the dog to see more clearly.
In cases of Pannus, reducing a dog’s exposure to the sun can help to naturally reduce the amount of pigmentation that has developed in the cornea. I’ve actually had one dog get completely cured because his Dad makes him wear Doggles whenever he goes outside. No exposure to UV light equals no Pannus.
There are varying reasons why dogs make excellent companions. Good-natured, joyful, and kind, they’re some of the most sociable and intelligent pets. They can develop empathy, sense jealousy, and are closer in mental likeness to their human companions than one would think.
It’s good for owners to know that while dogs aren’t totally colorblind, they don’t have free rein when it comes to sight compared to humans.
So the next time you leave a red toy on a green or a red carpet near your dog, and he doesn’t notice, remember that he just can’t see it. Try a yellow or blue one instead.