Dog Vision Explained
How do dogs see the world? Do they see colours? How do they see at night? Understanding dog vision so we can better understand our dogs.
How do dogs see the world we share?
Relative to us, dogs see the world from a much lower perspective since they are at a lower eye level. This is something that we as dog owners sometimes overlook. To most dogs we are giants. This changes the whole perspective. On the other hand dogs are closer to the ground and may see things that we usually miss. So although we are sharing the same world, views are very different.
Do dogs see colours or just black and white?
Our eyes are similar to those of dogs but yet have certain differences that give us a different view of our surroundings. The eyes of humans and dogs have cells called cone cells. These cells are responsible to detect colours.
Human cone cells can detect three colours; Red, Blue and Green (Trichromatic vision). This makes us see the world how we do.
Dog cone cells can detect two colours; Yellow and Blue (Dichromatic vision). This makes dog vision less coloured than ours and based on shades of yellow and blue.
The picture below compares how the same colour spectrum is seen differently by humans and dogs.
In addition, the number of cone cells that dogs have is lower compared to that of humans. So although dogs see well during the day they do not see as sharp as we do. Humans have the central area in the retina, called the fovea centralis, composed only of cone cells. Dogs on the other hand have less cone cells in the fovea centralis because there are other cells called rod cells (responsible for night vision) present in the area. It is this difference that gives us sharper vision in daylight.
How do dogs see at night?
Night vision is determined by the number of another type of cells in the eyes called rod cells. Rod cells are more sensitive than cone cells and are mainly used for night vision. Rod cells cannot distinguish colours and have almost no ability to render colour vision. This is why at night we see more shades of objects rather than colours.
Dogs have more rod cells than humans and this makes them better at night vision. It is estimated that dogs can see in light that is five times dimmer than what humans would need to be able to see at night.
Dogs have another advantage that makes them better at night vision. There is a layer of cells in the eyes of dogs that is called the tapetum lucidum which is essentially a layer of cells that reflect light within the eye. This reflection results in more light in the eye when at lower ambient light. This helps dogs see better at night.
This is also the reason why your dog’s eyes shine at night. The shine that you see is the result of this reflection by the tapetum lucidum.
Dogs see in shades of yellow and blue and their day vision is not as sharp as that of humans. Dogs have very good night vision and can see in light that is five times dimmer that what humans need to be able to see at night.