Can Dogs See Colour?
Do our dog companions have the same appreciation as us for the green grass in the park and the bright red toy hiding in it? Do colours look blurred from a canine perspective? And do dogs even see colour? Thanks to recent studies, we are starting to gain a better understanding of dog vision. Here is how dogs really see the world.
Can dogs see colour?
Many people believe that dogs see in black-and-white, and are unable to distinguish between the myriad of colours in their environment. However, this is inaccurate. Scientists have demonstrated that dogs can see colours, but their perception of different shades and intensity is likely to be different than people.
How does dog vision differ from human vision?
Although there are many similarities among mammals, dogs and humans have evolved with some different behavioural requirements of vision. For example, many wild dogs are actually crepuscular – this means that they are most active during dawn and dusk when levels of light are low. Humans, however, are naturally diurnal – most active during the day. This is just one example of many behavioural and anatomical reasons for the differences in vision between dogs and humans.
Range of colour
Light from our environment is processed by a structure called the retina, in the back of the eye, which is connected to the brain via the optic nerve. To reach the retina, light will be focused by travelling through the cornea (outer eye surface) and the lens. There are two particularly important cell-types in the retina – rods and cones. These are both types of photoreceptors.
The cones are largely responsible for colour vision. People are trichromatic, meaning we have three types of cones – blue, red and green. However, dogs are dichromatic and have only two cone-types – blue and a combined red/green. This essentially means that a dog’s ability to distinguish between colours is more similar to that of a red-green colour-blind person.
A dog’s vision has evolved to allow them to hunt well at dawn and dusk. This means that they have a greater number of the second type of photoreceptor, rods, than people. Rods are primarily responsible for detecting movement and can function in lower light levels than cones.
Wider degree of peripheral vision
Dogs have amazing peripheral vision. While humans have a field of view that extends to 180 degrees, some dog breeds can see 240 degrees, giving them an almost panoramic view. The fact that their eyes are set wider apart than ours also helps them see things that we would have to turn our head to notice.
Dogs are believed to have 20/75 vision; this means that a dog is able to see a visual pattern at a distance of 20 feet that a human with normal vision would see from 75 feet away. Therefore, objects tend to become blurry for them at a closer distance than they would for humans.
Dogs are more sensitive to changes in motion than humans. This is partly due to the higher numbers of rods in their retinas. These days we can hardly imagine our furry friends going on the prowl at night, but their ability to easily detect motion, combined with their excellent vision in dim light, made them quite fearless hunters in the wild.
What colours can dogs see best?
The answer to the question can dogs see colour is a definite yes, but there are certain colours that they are thought to see better than others. A dog is considered to have deuteranopia which is a form of colour-blindness. They are primarily able to see blue, yellow and grey and probably unable to distinguish between red and green. It is important to remember that there are limitations in our ability to be sure – clearly, we can’t ask the dogs what colours they can see!
What do dogs see when they watch TV?
Dogs are usually the first ones in the family to take you up on a movie night offer. While some of our beloved pooches seem to be mesmerised by the images on the screen, others seem relatively non-plussed. Although the sounds coming from the speakers are the biggest incentive for paying attention, the images can play a role as well.
It turns out, there is another fascinating aspect of dog vision that explains this behaviour. Dogs have a higher ‘flicker rate’ than humans. This means that while the rate of frames per seconds for humans is 60, for dogs a smooth image is achieved only above 70 frames per seconds. This means that higher-resolution screens provide a much clearer source of entertainment for the canines in the house than the old television set, which might be one of the reasons why they’re more likely to join you on a binge-watching weekend these days.
Do sighthounds have better vision than other dogs?
Sighthounds are dogs historically bred for hunting by speed and sight, rather than scent. Their vision extends to a whopping 270-degree field, allowing them to effectively scan the horizon for possible prey. Their retina has a longer than normal visual streak, a horizontal area with a high concentration of cones. Interestingly, it has been observed that this is a trait common only among dogs with long noses. Short-nosed canines such as Boston Terriers or Chihuahuas have a shorter visual streak.
Our understanding of dog vision gives us fascinating insight into how our four-legged friends actually experience the world and we can’t wait for scientists to keep surprising us with more findings. But did you know that one of the most impressive things about your dog is actually their sense of smell? Find out how important it is and how it compares to our own sense of smell, next.