We know that dog noses and ears completely exceed a human’s ability to detect scents and sounds. But are their eyes stronger than ours? Though dogs may not be able to see all the colors that we do, how do canine eyes fair in the dark?
A dog’s ability to see in the dark comes down to a simple matter of rods and cones. Human eyes possess more cone cells, which allow us to see vibrantly in color with greater distinction than the color variations canine eyes can detect. However, dogs are able to see in the dark better than we, because they have more rods (light-sensing cells) than we do.
Dogs have large pupils, and in their retinas they have more rods that actually respond to dimmer lights. The rods help distinguish between light and shadow, allowing dogs to detect motions and movements at greater distances. In addition to this, the canine also has a mirror-like apparatus in the back of their eyes that reflect light, called the tapetum lucidum. The tapetum (which is what causes the glow-affect that dog eyes get when light is shined on them at night, called “eyeshine”) allows the retina a second chance to absorb light the area, by “reading” the light and reflecting it back to the retina. Though this does give the dog better visibility at night, it can also actually scatter the light somewhat, making the accuracy of what a dog sees slightly weaker. For example, a dog with perfect 20:20 vision might have something nearer to 20:80 when the light is low.
Paul Miller, a clinical professor of comparative ophthalmology at the University of Wisconsin-Madison says, “ Dogs have evolved to see well in both bright and dim light, whereas humans do best in bright light. No one is quite sure how much better a dog sees in dim light, but I would suspect that dogs are not quite as good as cats. Dogs can probably see in light five times dimmer than humans can see.”
In conclusion, dogs do have a greater ability to see in the dark than we do though they may not have complete accuracy of “night vision.” So next time you grab the leash for the evening outing, maybe considering letting your trusty pup take the lead!