Are dogs really colour-blind?

Many people think that dogs are colour-blind, but that isn’t true – at least not entirely. Although dogs aren’t completely colour-blind, they do see the world differently from humans. We humans have three types of colour receptors in our eyes. You can think of colour receptors as cones. Dogs only have two of these, so their colour vision is more limited.

How did they discover that dogs aren’t colour-blind?

Scientists have discovered that dogs are not completely colour-blind through experiments testing colour vision. Dogs can therefore still see certain colours. Scientists trained dogs to recognise and select certain objects based on colour; in doing so, they discovered that dogs could consistently distinguish between blue and yellow, but had difficulty with red and green. By measuring the response of the cells in the retina to different wavelengths of light, researchers were able to determine which colours dogs can actually see.

Colours that dogs can indeed see

So dogs are not colour-blind; they simply see colours differently. They have two colour receptors instead of three, which means their colour spectrum consists only of blue, violet and yellow. Red appears somewhat yellowish to dogs, they cannot see green at all, and purple appears grey to them. Humans can see between seven and ten million different colours, which is more than we have names for. So dogs are not colour-blind; they see blue, green, grey, cream, black and white. Dogs are much better at detecting movement.

• Blue → Blue (as we see it)
• Yellow → Yellow (as we see it)
• Red → Probably dark grey or brown
• Green → Also a greyish shade

Which colours can’t a dog see?

Due to the limited number of cones in their eyes, dogs cannot see colours such as red and green. To dogs, colours such as red and green look more like different shades of yellow. Dogs perceive shades of blue and purple more clearly.

What do dogs see that we cannot?

Dogs are not colour-blind; they also have much better night vision than humans, thanks to their tapetum lucidum. This is a light-reflecting layer of cells directly behind or sometimes within the retina that enables the eye to see better in the dark. Dogs not only see better in the dark, but movement and shapes are also more clearly visible to them.

How does colour blindness affect behaviour?

Dogs are not colour-blind; they also choose their toys based on colour. Blue and yellow toys stand out much more than red or green ones. They will therefore be more inclined to choose blue and yellow toys. The same applies to training; it is best to choose colours that dogs can see clearly.

Why have dogs developed a more limited colour vision?

This limited colour vision was not a disadvantage for dogs, as they have mainly adapted to a life as hunters in twilight. Instead of colour vision, their vision is optimised for exercise and contrast, which helps them detect prey more effectively in low light. Furthermore, dogs have more rods (light-sensitive cells) in their retinas, enabling them to see better in the dark than humans.

Are there any glasses or technologies that can help dogs with their vision?

There are a few technologies and aids that can improve or adapt dogs’ vision, although they do not have the same effect as glasses for colour blindness in humans. Here are a few examples:

1. Doggles (Dog Glasses)
   • These are special sunglasses for dogs that offer protection against bright sunlight, UV rays and wind. They are particularly useful for working dogs, such as police or rescue dogs, and for dogs with eye problems such as cataracts.
2. Colour-filtering glasses
   • Although there are no glasses that fully correct dogs’ colour vision, experiments are being conducted with glasses that filter out certain wavelengths of light to improve contrast. This can help dogs distinguish between certain colours or objects.
3. Night vision technology
   • Dogs already see well in the dark, but some scientists have experimented with infrared cameras or glasses that allow dogs to see even better in complete darkness.
4. Bionic eyes
   • Research is being conducted into bionic implants for dogs with serious eye conditions such as cataracts or blindness. These technologies are still in the experimental phase.

Do dogs have better night vision than humans?

Yes! Dogs see much better in the dark than humans, thanks to a number of evolutionary adaptations:

• Tapetum lucidum: This is a reflective layer behind the retina that reflects light. This helps dogs see better in low light and gives their eyes that characteristic glow in the dark.
• More rods in the retina: Rods are light-sensitive cells that aid vision in dark conditions. Dogs have more of them than humans, enabling them to navigate better in low light.
• Larger pupils: Dogs can dilate their pupils further than humans, allowing more light in and enabling them to distinguish objects better in the dark.

Thanks to these characteristics, dogs can see much better than we can at night and at dusk. This is particularly useful for their hunting instincts and sense of direction.

What does this mean for dog owners?

When choosing toys or training equipment for your dog, bear their colour vision in mind. Blue and yellow toys stand out the most, whilst red and green objects tend to appear greyish and are harder to distinguish. Your dog also has an advantage on night-time walks: whilst you struggle to see objects, your dog can orientate themselves perfectly well. This is thanks to their excellent night vision and experience of movement.

Conclusion: are dogs colour-blind?

Although dogs do not see the world in the full colour palette that humans do, this does not mean they are colour-blind. They have a more limited colour range and can perceive blue and yellow particularly well. They also compensate for this with excellent night vision and a keen ability to detect movement. This insight helps us to better interact with our four-legged friends and provide them with an environment that suits their unique way of seeing.