How Do Dogs See?

If you're like me, there have been times where you've felt bad about your dogs being in the dark but wondered why your cats are fine in the dark? I also wonder what exactly a dog can see, clearly they can see the Frisbee you throw, or the stick out far away, but sometimes it seems they can't see stuff right in front of them. Is there rhyme or reason to what they see, and how they see? I did a little digging, and I found out a few tidbits:

• 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 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. (source: Vet Info for Dogs)

Model Credits: Wilbur (top) and Edna (left)