Dogs are not color blind. Although dogs’ ability to distinguish colors is not as strong as humans and cannot distinguish long-wavelength light waves, dogs are not color blind and can see black, white, gray, blue, yellow and other colors.

Dogs have color weakness and see green as off-white and red as black or brown. Therefore, guide dogs can distinguish traffic lights, but there are some differences from the colors observed by humans.

How do dogs distinguish colors?

There are two types of cone cells in the dog’s retina, which can identify short wavelengths and medium and long wavelengths of light waves. That is, you can feel blue light (light waves with short wavelengths) and red and yellow light (light waves with medium and long wavelengths). Due to the small number of cones, the colors of the world in dogs' eyes are very monotonous, unlike the colorful world in human eyes. Humans, however, have three types of cones that allow us to see all colors of light in the visible spectrum. Since dogs only have two types of cones, the colors a dog can distinguish are the same as a person with red-green color blindness.