Question: My colleague keeps insisting that dogs only see two-dimensionally, but I believe they must be able to see three- dimensionally, since they are capable of catching objects and running obstacle courses (eg. ladder climbing). The answer, please. Thanks! Kathy
Answer: Kathy- Dogs have binocular vision over about 80 degrees of their visual field, which is enough for good quality binocular vision. This does vary some by breed, with collies probably having a smaller area of binocular vision than a golden retriever due to the placement of the eyes and length of the nose. Dogs have dichromatic vision, meaning they see in only two colors, which might be confusing your colleague. I have a friend who is blind in one eye who can still catch Frisbees pretty well, so I'm not sure that binocular vision is essential for tasks like this but dogs do have binocular vision normally and should have good depth perception. Mike Richards, DVM 1/24/2003
Dogs can see in much dimmer light than humans. This is because the central portion of a dog's retina is composed primarily of rod cells that "see" in shades of gray while human central retinas have primarily cone cells that perceive color. The rods need much less light to function than cones do.
Dogs can detect motion better than humans can.
Dogs can see flickering light better than humans. The only significance to this appears to be that dogs may see television as a series of moving frames rather than as a continuous scene.
Dogs do not have the ability to focus as well on the shape of objects (their visual acuity is lower). An object a human can see clearly may appear to be blurred to a dog looking at it from the same distance. A rough estimate is that dogs have about 20/75 vision. This means that they can see at 20 feet what a normal human could see clearly at 75 feet.
Dogs are said to have dichromatic vision -- they can see only part of the range of colors in the visual spectrum of light wavelengths. Humans have trichomatic vision, meaning that they can see the whole spectrum. Dogs probably lack the ability to see the range of colors from green to red. This means that they see in shades of yellow and blue primarily, if the theory is correct. Since it is impossible to ask them, it is not possible to say that they see these colors in the same hues that a human would. Whether or not the ability to see some color is important to dogs or not is hard to say.
Also consider the perspective that dogs see the world from. A dog with its eyes about 12 inches off the ground certainly sees the world a different way than a human with eyes about 48 inches off the ground like many 5th graders.
As humans we tend to think of dog's visual capabilities as inferior to ours. It is different but it may suit their needs better than possessing accurate color vision would.
Michael Richards, DVM
Q: Dr. Mike, I'm a fifth grader from Grass Range, MT. This year I'm doing my science fair project on dogs. Seeing if they're colorblind or not. My teacher said to find out as much info as possible. So I was wondering what you could tell me about their sight. Do you have any proof about if they're colorblind or not.
A:. The current thinking is that dogs see in color but not in the way that humans do. I will try to find some information on this for you (I know that there was an article in one of the veterinary journals, but I can't remember which one) and forward it on.
The latest article on this discussion that I can find a reference to is the December 1995 issue of the Journal of Veterinary Medicine. "Vision in dogs", was written by Paul E. Miller, DVM and Christopher J. Murphy, DVM, and published in the Journal of the Veterinary Medical Association (JAVMA, vol. 207, no. 12, pp. 1623-1634, Dec. 15, 1995).
If memory serves me right, the thinking is that dogs only see blue and yellow because they have many less of the cones (color vision cells) than people. On the other hand, they have many more rods (low light and motion detecting cells) so they see much better in the dark and they can detect much smaller motions than humans.Michael Richards, DVM
Michael Richards, D.V.M. co-owns a small animal general veterinary practice in rural tidewater Virginia. Dr. Richards graduated from Iowa State University's College of Veterinary Medicine in 1979, and has been in private practice ever since. Dr. Richards has been the director of the PetCare Forum...