4 Facts About Dog Eyesight You Probably Don’t Know
Staring into a dog’s pleading eyes might cost you the last bite of your sandwich or the leftovers from your dinner plate, and there’s no doubt in your mind those big puppy dog eyes hold a lot of emotion. There’s more to your dog’s eyes, however, than their ability to make you feel all warm and fuzzy inside. The matter of dog eyesight is subject to more than one misconception. Understanding how your dog sees the world will make your friendship even stronger, so now’s the time to separate fact from fiction. Here are the top four interesting facts about dog eyesight every dog lover should know.
#1. Dogs are NOT Colorblind
People like to think of dog eyesight like watching an old black and white TV show. The truth is, however, dogs are far from colorblind. They see the world in shades of blue, yellow, green, and gray in addition to black and white. The reason dogs don’t see colors the way people do has to do with the color receptors in the eyes.
Called cones, these receptors are located in the retinas and are responsible for perceiving color. Humans have three kinds of cones, and each one is sensitive to a specific color (red, green, and blue). Dogs, on the other hand, only have two types of cones—one for yellow and one for blue. This gives them what’s called dichromatic color perception while humans have trichromatic color reception. The Dog Vision website offers a clear look at the difference between a dog’s perceived color spectrum and a human’s.
#2. Dogs are Technically Nearsighted
Remember the chart of letters your eye doctor asks you to recite out loud? That’s called a Snellen eye chart, and it’s used to give your doctor an idea of your vision clarity. It’s a good way to screen people for near and farsightedness, and the test also contributes to determining whether or not you have 20/20 vision.
Good luck getting your dog to read off those letters, but if he could take a Snellen eye test, he’d probably get to the third line before everything turned into a blur. Psychology Today reports dogs most likely have 20/75 vision. This means your pup can see things at 20 feet away that a person with 20/20 vision can see from 75 feet away. He’s nearsighted, but don’t feel too bad for him. Dogs have evolved over centuries to rely on their other senses (smell especially) to make up for their less-than-stellar vision clarity.
#3. Dogs Have Better Peripheral Vision Than Humans
Peripheral vision is what your eyes can detect on the sides while facing forward. It’s how your mom always knew what you were doing without having to look at you, and it’s also what makes dogs great hunters. While the average human has a field of vision of about 180 degrees, dogs have much wider peripheral vision. The exact number depends on the dog, but on average, dogs have a visual field of about 250 degrees. When your dog goes running after a cat you didn’t know was there, you have your inferior peripheral vision to blame. Your dog’s eyes are set farther apart than your own, and this allows him to see things you’d have to turn your head to catch.
Even within the canine kingdom, some dogs have better peripheral vision than others. Snub-nosed dog breeds have the worst peripheral vision and can typically see at a range of around 220 degrees. According to Canidae, sighthounds, like Greyhounds, Rhodesian Ridgebacks, and Basenjis, have the best peripheral vision out of all dog breeds. It has to do with their long, thin noses and the position of their eyes. Some sighthounds have a field of vision of 290 degrees. They put it to good use while spotting potential prey.
#4. Night Vision is a Big Part of Dog Eyesight
Cats usually get all the acclaim for being able to see in the dark. Dogs, however, also have pretty impressive night vision. It has to do with the structure of their eyes and a few extra special features humans don’t have. When your pup stares up at you with those irresistible puppy dog eyes, take a look at his pupils. Dogs have extra large pupils that, in addition to being seriously adorable, allow your pup to take in more light. All that light is then absorbed by light receptors in the eyes called rods. Human eyeballs have rods too, but dogs have a lot more. They allow them to pick up and process even faint hints of light and use it to see better in the dark.
To complete your dog’s built-in night vision goggles, Service Dog Central explains dogs also have a special “mirror-like structure” called a tapetum located in the back of the eye. When light enters the eye, it’s reflected off the tapetum and sent backward toward the retina. This gives the retina a second chance to collect as much light as it can. The tapetum is also responsible for that eerie glow your dog’s eyes produce when light hits them in the dark. The glow is actually light being reflected off the tapetum and sent back out of the eye. All these special features combine to give your dog the super power ability to walk through the living room at night without banging his toes into every piece of furniture.
By seeing the world through your dog’s eyes, you can better understand what’s going on behind those baby blues or big ol’ brown peepers. Colors aren’t the same and far away things are a little blurry, but your dog can see a huge field of vision without turning his head, and a little darkness won’t slow down his nighttime wanderings. Dog eyesight has it’s fair share of disadvantages, but at the same time, your dog can see things you have no chance of picking up. The next time your stare lovingly into your dog’s eyes, try to see what he sees.