How do cats and dogs vision compare to horses and cows? Demystifying cat and dog vision comparison with large farm animals

Who will win?

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Carnivore animals (predators) see the world through a different visual system than farm herbivores (cows, goats, sheep, horses)

Dogs and cats have a totally different vision when compared to that of large farm animals like horses and cows.
Dogs and cats are carnivores coming from predatory animals through evolution while most farm animals, including horses and cows, are herbivores which are prey species. Maybe you are wondering what animals eating habits have to do with the way animals see the World. It has a lot to do and cats or dogs vision and visual system, in general, evolved to what is today thanks to the feeding needs and behavior of these animals during thousands of years of evolution.
The visual system is composed of the eyeball (with attachments like eyelids and tear glands), the optic nerves, internal connections inside the brain, and the visual cortex of the brain, located at the back of the head. There is no best or ideal visual system in animals but that serving the best to the specific survival strategy of a given species.
Predators (including casual predators like domesticated dogs and cats) require focusing their sight on usually fast-moving objects located ahead. To do this, the visual field of each individual eye overlaps with each other (when you close one eye you are left with the visual field of your other open eye). When both eye fields combine (left and right), this arrangement brings to life more vivid details of the object of interest (like a mouse trying to escape from a cat, for instance). This cooperation of both eyes to sharply focus frontal (ahead), far located (and usually moving) objects is called binocular vision. This kind of visual field integration is also present in us humans. Therefore, we also have binocular vision and use it to chase things or to detect danger ahead, for instance.

Predators (including casual predators like domesticated dogs and cats) require focusing their sight to (frequently running) objects located ahead.
Predators (including casual predators like domesticated dogs and cats) require focusing their sight on (frequently running) objects located ahead.

On the contrary, the visual fields of each individual eye in prey animals never overlap (like in domestic horses, cows, sheep, goats, and many others potentially “edible” to carnivores). Hence, these animals lack binocular vision. In compensation, they have very wide visual fields on each eye that allow them to spot close objects in a very panoramic way. Thus, they have a much broader field of vision than carnivores, allowing them to detect things at very lateral angles, even coming from behind. Predators like dogs and cats cannot definitely do this.

Image showing the differences of visual fields of predator animals (like dogs) and prey animals like the horse
Prey animals like horses (A) have visual fields from each individual eye that never overlap with that of the opposite side, enabling them to see objects located very laterally, or even clearly behind them, while predators like dogs and cats (B) require focusing their vision to see frontal objects sharply. Their visual fields overlap creating a binocular vision (just as in us humans). The white triangle in front of the horse’s nose is a blind spot.

This way, a horse, for instance, can detect someone approaching from behind or laterally and start the best possible response for which he is best at: running!

Horses (as other herbivores) have to be very aware of their surroundings if they want to survive

Although prey animals are good at detecting visual changes in their surroundings (like for instance potential threats) located laterally, the not-overlapping of their visual fields creates a blind spot in front of their noses. Anything that moves in that space cannot be seen (which is weird for us humans to imagine). Dogs and cats (and us humans) can perfectly see objects moving in that area (and even further away) and will readily bite or scratch if menaced as this menace is rapidly detected by the highly accurate visual system. The menace reaction can be used to test the visual system in dogs.
Animals can perceive colors differently from us, but despite that, their visual system is perfectly adapted for their survival.

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