A lot of people say that dogs are color blind. Are they? How about cats? That’s what a reader asked — here’s my answer!
Q: Can dogs and cats see color? I always see conflicting answers to this question. What else is different about their vision?
A: Part of the reason for conflicting answers is that vision varies, as can the way it’s evaluated. Here’s what we know.
Cone cells in the eye determine visual acuity and color discrimination. Dogs have two populations of cones, says veterinary ophthalmology specialist Ron Ofri, DVM, who spoke earlier this month at the Western Veterinary Conference in Las Vegas. One cone population absorbs light in the blue-violet spectrum, the other in the red spectrum. That means dogs can see colors, but they are unable to distinguish between green shades.
A dog’s color vision is similar to that of a human who is color blind. Unlike people with normal vision — three cone populations in blue, green and red wavelengths — those people are missing either the red or the green cone population.
Cats have three cone populations, but several studies have determined that they do not have rich color vision. What they do have is highly sensitive night vision. Cats have unusually large corneas and pupils, allowing more light to pass through them and reach the retina. In the proceedings for his talk, Dr. Ofri notes that the amount of light that falls on a cat’s retina is 6 times the amount of light that reaches a human retina. In addition, cats benefit from a structure called the tapetum lucidum, which gives cats higher vision sensitivity at night, but not during the day.
Which animals have the best color vision? That prize goes to certain species of birds and fish, with four cone populations, the fourth absorbing light in the ultraviolet area of the spectrum. When it comes to richness of color vision, they beat out cats, dogs and humans.
Read more, including about the dreaded medical condition known as “bloat,” in this week’s Pet Connection!
