A Dog’s Eyes

Did you know?

  • Dogs are predators so their eyes face forward.  Animals that are preyed upon tend to have eyes on the side of their face to give them a wider view of the world so they can keep an eye out for danger.  However dogs’ eyes are placed more to the side of their heads than humans, giving them a more panoramic view of the world than us.  Dogs have a 240 degree field of view, cats have a 200 degree field of view and we have a 180 degree field of view.
  • Dogs don’t need eyebrows in the same way as humans do to stop sweat getting into their eyes, as dogs only sweat from the pads of their feet.  Where dogs have markings that look like eyebrows, the markings can facilitate communication as the markings accentuate the movement of the eyes.
  • Dogs find direct eye contact threatening – don’t stare at a dog.
  • Dogs’ eyes have fewer cones than humans, which means that they don’t have the full range of colour vision that we do, but dog’s are not colour blind.
  • The pupil in a dog’s eye is larger than humans, which lets in more light, but results in a loss of depth of field.
  • Dogs have a much higher proportion of rods in their eyes than we do, which gives them better visibility in low light.
  • Compared to humans, dogs would be considered near sighted.  A human with 20/20 vision sees an object clearly at 20ft.  Dogs have 20/75 vision which mean that they see an object clearly at 75ft that we’d see clearly at 20ft.
  • Dogs have a third eyelid.  Its primarily purpose is to protect the eye, but it also produces tears.  Although dogs’ eyes can produce tears, dogs don’t weep.
  • Dogs seem to have eyes that are particularly sensitive to changes in their environment and have excellent motion perception, which is particularly useful to herding breeds and sighthounds.
  • There’s a mirror-like layer that is found just behind the dog’s retina called the tapetum lucidum. This special structure helps dogs make the most out of small amounts of light.  It is due to the presence of the tapetum lucidum that dogs show that eerie Halloween-like eyeshine seen when the glare of a flashlight or a car’s headlight hits this area. This is referred to as “eyeshine.” The green color is simply due to the layer of shiny cells lining the tapetum lucidum.

Photo by Jose Rocha from Rio de Janeiro, Brasil – Flickr, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=3493364