Welcome to “Debarking Pet Myths,” a monthly series dedicated to addressing common myths, misconceptions and old wives’ tales about dogs and cats.
Can dogs see colors? That’s a frequently asked question about our four-legged friends’ vision. And as a kid, you may have been told that dogs don’t see colors — just black, white and shades of gray. While no one is sure about the origins of this myth — there appear to be several — we now know that dogs do see colors, just not the same way people with normal color vision do. The number and vibrancy of the colors they see are limited compared to ours.
The science behind color vision
The retina, which lines the back of the eye, has two main types of cells that sense light (aka photoreceptors):
- cones, which function in bright light, are sensitive to different wavelengths (that is, colors) of light and give the ability to see fine detail; and
- rods, which detect light levels (brightness or dimness) and motion.
Human eyes have three types of cones, each sensitive to different light wavelengths, and typically referred to as red, green or blue based on the photopigment they contain. The combined activity of the red, green and blue cones is what gives people their full range of color vision. In contrast, canine eyes — like those of many other mammals — possess only two types of cones, those that detect blue and yellow. Scientists believe the color vision of dogs is roughly similar to the vision of people with red-green colorblindness since they, too, only have cones with two photopigments. So while people with full color vision see a rainbow of colors — red, orange, yellow, green, blue and violet — dogs see grayish brown, dark yellow, light yellow, grayish yellow, light blue and dark blue.
Human eyes also typically have more cones than canine eyes, which suggests that dogs’ color vision may not be as rich or intense as human color vision. However, dog eyes have more rods, which gives them an advantage when it comes to seeing in low light or identifying moving objects. A reflective layer under the retina in dogs’ eyes, called the tapetum lucidum, magnifies incoming light to enhance their night vision. We “see” the tapetum lucidum as dogs’ eyes shining in the dark.
So now you know why your dog may have more fun chasing after a bright yellow tennis ball on green grass under blue skies but have trouble finding the red ball. The yellow ball is simply easier for your dog to see!