Have you ever wondered whether your dog could see (and appreciate) the striking pink or nuanced teal color of a new toy? Humans on TikTok are using a dog vision filter to help answer this question. With the filter on, you’ll see the world in shades of blue, yellow and gray—the only colors your pup can perceive.
But is this really how our furry friends see the world? Not exactly, experts say—there’s way more to your pet’s vision than color perception.
Scientists once thought dogs saw only in black and white. The idea took off in the public imagination in the 1940s, when optometrist Gordon Walls published his influential book The Vertebrate Eye and Its Adaptive Radiation, in which he claimed that dogs could only weakly see color, if at all. The myth was finally debunked in 1989 when ophthalmologist Jay Neitz, then at the University of California, Santa Barbara, and his colleagues discovered that canines could see blues and yellows but not reds and greens. Some humans, about 8 percent of men and 0.5 percent of women, are similarly red-green color-blind.
It turns out that dogs possess two types of color-sensing receptors, called cones, in their retinas. This makes them similar to most mammals—including cats, cattle and pigs—and unlike humans, who have three cones.
“Our work has had a big influence, and lots of people now understand what color vision in dogs really is,” says Neitz, who is now an ophthalmology professor at the University of Washington.
But to really understand how dogs see the world, we need to move beyond color, says Sarah-Elizabeth Byosiere, an animal behaviorist and former director of the Thinking Dog Center at Hunter College. While a green or red ball lying on grass would not stand out easily to your pet, it might challenge them to identify it by its other features—such as its movement, shape and the way it reflects light, Byosiere says. That challenge could either be enriching or frustrating. “It all depends on an individual dog’s behavior,” she says.
If you’re really trying to imagine the world through the eyes of your dog, you should picture everything a lot blurrier. Most dogs have 20/75 vision, meaning that they must be 20 feet away from an object to see it as well as a human with clear vision who is standing 75 feet away.
“Everything looks clear and detailed in those [TikTok] videos, but it wouldn’t look quite as clear to dogs,” Neitz mentions.
But unlike humans, who see very poorly in low light, canines have evolved to see well in both daytime and nighttime conditions, explains Paul Miller, a veterinary ophthalmologist at the University of Wisconsin–Madison. Though dogs have fewer color-sensing cones than humans, they have more rods, the cells that help with night vision. They even have a unique structure in their eyes called the tapetum lucidum, a mirrorlike membrane that allows them to see in six times less light than humans can. The tapetum, which some other animals, such as cats and cattle, also possess, sits behind the retina and reflects light back onto it, giving the receptors a second chance to gather more visual detail. It’s also the reason your pet’s eyes glow in photos and in the dark.
Also important for dogs’ perception is their sense of smell, which is 10,000 to 100,000 times more powerful than that of an average human. This is as true for chihuahuas and pugs as it is for bloodhounds. While humans have about five million smell receptors, dogs possess up to a billion and can communicate with one another with chemical signals. They can pick up odors as far as 12 miles away.
And canines’ mighty sense of smell is inextricably linked to how they see the world. A study published last year in the Journal of Neuroscience revealed that canines’ brain has a direct connection between their olfactory bulb, which processes smell, and their occipital lobe, which processes vision. This integration of sight and smell had not been observed before in any animal species, the authors stated.
The results raise the question of whether dogs’ sense of smell is orienting their sight, Miller says. “It’s pretty wild,” adds Miller, who was not involved in the study. “They [may be able to] smell in 3-D.”
So while humans may be attuned to the aesthetics of color, dogs simply aren’t, Neitz says. “I’ve had dogs all my life. And I never really felt like, ‘Oh, my God, my poor dog’s world is limited from a color vision standpoint,’” he says. They live in a very rich olfactory world that humans can’t appreciate, Neitz adds.
When it comes to buying toys for our canine companions, we don’t always have to select the two colors they can see: yellow and blue. Byosiere recommends getting one red and one blue toy to enrich your pet’s play. You may want to throw the red one on the green grass so that your pup uses its nose and then throw a blue one so that it uses its eyes.
“These animals are not deprived in any way,” Byosiere says. “It’s just that they just see the world in a different way.”