Dog vision

Colour perception

Dogs are not completely colour blind, but unlike humans who have three different colour sensitive cone cells in their retina (red, green and blue) dogs have only two (green and blue).

This does not mean that dogs can't see red objects! It only means that they can't distinguish red, green or yellow objects based on their colour. However they can still distinguish a red ball from a green one if there is a difference in the perceived brightness of the two.

Red, yellow and green are perceived as one hue. Blue and purple are perceived as a second hue. Cyan and magenta are perceived as a neutral hue (grey).

Dogs can also see varying shades of the same colour, but not to the same level of detail that we can. Some shades are just to close together for a dogs eyesight, therefore two slightly differing shades would be perceived as the same shade.

Why can dogs see better in the dark than humans can?

Dogs can see much better in the dark than we can thanks to having a layer of tissue behind their retina called a Tapetum lucidum. The Tapetum lucidum reflects visible light back through the retina, increasing the light available to the photoreceptors. This improves vision in low-light conditions.