🐾 Dog Food Knowledge: No. 16, Do Dogs Really Only See Blue and Yellow?

It has been repeated so many times that people now say it as if it is fact: “Dogs can only see blue and yellow.” 

Except that is not true. 

And we are going to explain why it matters.

The truth is more interesting. Dogs do not see in black and white, but they do not see the same rainbow we do either. The difference lies in the cones, special cells in the eye that detect colour. Humans have three types of cones. Dogs have two. So, the colours they see are fewer, but not gone.

But saying dogs only see blue and yellow is a marketing simplification. What they actually detect is a spectrum of blue-violet through to yellowy-brown, with most reds and greens collapsing into dull greys or muted tones. That yellowish brown, by the way, is a very real and important part of their world, especially when it comes to food, toys, and even grass.

Red, for example, doesn’t look red to a dog. It appears as a dark brown or grey. Green is similar. But blue and yellow stand out more strongly. That’s why toy companies often push these colours. But it doesn’t mean they are the only colours a dog can see. They are just the most vibrant within their limited range.

The best way to picture it is this:

• Your world is a rainbow.
• Your dog’s world is a water-stained version of that rainbow, where some colours run together and others fade out.

It is not black and white. It is not blue and yellow. It is a smaller, flatter version of our colour world, with detail still visible but some of the flair removed.

We have even seen people making videos with lenses that only show blue and yellow in an attempt to say, “This is what your dog sees.” 

Problem is, it is not true. 

It relies on a gullible mind to convince, and the user creates an image of knowledge for their victims. 

They are the pied piper of leading through their own imagination.

So why do people keep saying it? Because marketing loves simple. And people repeat it without ever questioning whether it’s based on real biology. But the truth matters, especially when you are picking toys, designing treats, or feeding food with appearance in mind. If you think your dog can’t see a colour at all, you might assume the visual doesn’t matter. But they can see contrast. They can detect changes in brightness. They can see depth, movement, and tone.

And most importantly, they don’t need a rainbow to be intelligent. Their vision is built for what dogs need: detecting prey, tracking movement in the distance, and identifying members of their pack. That includes you.

So next time someone tells you dogs only see blue and yellow, remember this:

🔬 That’s not biology. That’s bad science repeated too many times.

📚 Scientific Evidence That Backs This Blog

If you want sources to prove this is true, here are a few of the most reliable:

Miller, P. E., & Murphy, C. J. (1995). Vision in dogs. Journal of the American Veterinary Medical Association, 207(12), 1623–1634.

Neitz, J., Geist, T., & Jacobs, G. H. (1989). Color vision in the dog. Visual Neuroscience, 3(2), 119–125.

Byosiere, S. E., Chouinard, P. A., Howell, T. J., & Bennett, P. C. (2020). What do dogs see? A review of vision in dogs and implications for cognition research. Animal Cognition, 23(6), 1027–1044.

All confirm that dogs do not just see blue and yellow. They see a range of muted tones, including greys, browns, blues, and yellows, with limited but meaningful perception across a full spectrum.

🧠 Another Marketing Myth: The Two Litre Water Rule and how marketing took the message over.

NASA once explained that a human needs around two litres of water a day. Almost instantly, drinks companies pounced. They turned it into a catchphrase. Everyone and their uncle started parroting it. It became modern-day advice, repeated without question.

But they left out the most important part. NASA also made it clear that a lot of that water comes from food. Fruit, veg, cooked meals. All of them contribute to hydration. You do not need to chug two litres of liquid.

The marketing world needed you drinking like a fish. That could not happen if the full truth was told. So they ignored it. And they still do.

Do you see how marketing works?

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Your dog, if it could talk, would worship you even more than it already does. 🐾