Why are dogs colorblind?

Answer

Hi Margaux,

The retina of a human eye is covered with light-sensitive cells that are divided into cones and rods according to their shape. The cones allow us to distinguish colors. The rods ensure that we can still see in low light.
There are three types of cones. These three types of cones are each sensitive within a specific wavelength range or color range. Simply put, there are red-sensitive cones, green-sensitive cones, and blue-sensitive cones. The differences between the three types of cones allow us to distinguish colors.

However, many mammals, including dogs, only have 2 types of cones, so they can naturally distinguish fewer colors than a human being. Dogs are therefore mainly red-green color blind. The color spectrum that they see is therefore much more limited than the color spectrum that people see (see also attached photo). Dogs look more in function of movements and smell and not in function of colors.