What Colours Can Dogs See?
Published Friday 29th September 2023
It is a common myth that dogs only see in black and white. This is not the case, although their colour vision is limited compared to humans.
Dogs evolved as hunters, just like modern wolves. On the one hand, this might make you assume that fantastic vision would be essential, however the dog evolved to hunt at night, dawn and dusk. A hunter doesn’t need full-colour vision at night, as colours simply disappear when the sun goes down. The key skill is to detect motion and to see things vividly in the half-light. In these respects, dogs’ eyes excel, and their eyes are super-sensitive to movement.
Humans, in contrast, evolved as daytime hunters, and that’s why we have better colour vision. At night, our eyes are hopeless without some kind of artificial light. At dawn and dusk, our brains have great difficulty identifying moving objects with certainty. Human vision contains more colour than a dog’s, however we are certainly not top dogs when it comes to colour vision in the wider animal world. Many insects, including bees and butterflies, as well as many fish and crustaceans, have far more light receptors than we do and can see far more colours in the rainbow and the world around them.
But a dog’s vision is still perfect – for a dog!
How Dogs & Humans See Colour
Both humans and dogs are able to see thanks to two main types of cells in the retina: Rods which detect light levels and motion, and Cones which help us to differentiate colours. Human eyes have three different types of cones, which allows us to identify colour combinations of red, blue, green and yellow. Dogs have only two types of cones, which means they can discern blue and yellow colour but are red, orange, green colour blind.
What Colours Can Dogs Not See?
The ‘missing’ reds and oranges will appear to dogs as the various shades of light brown labelled ‘tan’. The greens in grass, trees and other plants are also tan to a dog. That bright red ball lying in the lush green grass may be very clear to you, but to your pet dog, the ball and the grass are both brown. Buy your dog a yellow or blue toy, however, and it will be as visible to your dog as it is to you. Luckily for dogs, they rely on their sense of smell more than sight, so locating that ball in the grass won’t be too tricky, no matter what colour the toy is.
Can Dogs See Colours in Their Toys?
There is no evidence that a dog prefers a blue or yellow ball to a red or green one. They will, however, be likelier to lose track of a light brown ball in the light brown grass.
A blue or yellow toy is as visible to your dog as it is to you.
Do Dogs Have Good Eyesight?
It may come as a surprise to many people that dogs, in addition to their poorer colour vision, cannot see as clearly as humans. Beyond a certain distance, everything becomes blurry for them. They have a genetic short-sightedness that prevents them from seeing distant objects clearly. The degree of short-sightedness varies between dog breeds, and it comes as no surprise to learn that so-called ‘sight hounds’ such as the Afghan Hound, Greyhound, Irish Wolfhound, Scottish Deerhound and Whippet have better eyesight than Chihuahuas, Pugs and Bulldogs. However a dogs eyesight comes into its own at dawn and dusk, they can see just as well as they do in the daytime. They have retinas that function well in poor light. The shape of their eyes’ light receptor cells and a reflective tissue layer at the back of the eye that combine to create this low-light super vision.
And that reflective layer is why dogs (and cats) eyes always have a ‘red eye’ effect in photographs. Dogs also have a broader field of vision than humans, as their eyes are more on the side of the head than ours. This enables them to take in details that we would either miss or would be half-glimpsed things seen ‘in the corner of the eye’.