For many years, it was believed that dogs did not have the ability to
see color at all, that the world came to them mostly in black and white
and shades of grey. Today we know that this is not true - dogs do see
color, but because their eyes lack the three types of color receptors
that we humans have, they do not see the variety of color that we do. It
is similar to what we call red-green colorblindness. According to an
article on Smithsonian.com, "Whereas a human with full color vision sees
red, orange, yellow, green, blue and violet along the spectrum of
visible light, a dog sees grayish brown, dark yellow, light yellow,
grayish yellow, light blue and dark blue, respectively—essentially,
different combinations of the same two colors, yellow and blue."
Consequently, it has been thought that dogs do not rely on color to
distinguish between similar objects but that they use its relative
brightness or darkness. However, a recent study released in July of 2013
indicates that this may not be true and that dogs may actually be able
to distinguish between colors after all. More research will need to be
conducted as the test group was small, but this is indeed intriguing
Another belief we have is that cats by far, have better night vision
than either humans or dogs. To date, research indicates that this is
probably true but dogs' eyes have adapted well for vision in low light.
They have large pupils, which let in more light and more light-sensitive
rods in the retina. Additionally, the lens in a dog's eye is located
closer to the retina, making the image on the retina brighter.
One important advantage that dogs have for good night vision though, is
the tapetum which is a mirror-like structure that reflects light, giving
the retina a second chance to register light that has entered the eye.
It is also what makes a dog's eyes appear to "glow" in the dark.
So, if your dog is young and healthy, it is thoughtful but not really
necessary to leave a night light on for him when you go to bed. And
though it appears that more will be revealed with further research, your
dog may well be seeing the world similarly to how we see it too.
Deborah Dobson, FizzNiche Staff Writer