All species of animals experience the world in varying ways, using their senses to see, smell, taste, touch and hear everything around them - and if you happen to have a canine companion, you may have found yourself asking: what do dogs see?
Without examining the canine eye more closely, we know that (unless we are able to pick them up), a dog’s view of the world tends to be around knee-height - although some dogs, such as very tall breeds like lurchers, or smaller ones like dachshunds, also see the world from varying levels.
Human And Canine Eyes
Both humans and canine eyes share some similarities: they both have a central nervous system, which is used to interpret the information viewed through two eyes. They also have a retina, lens, pupil, iris, cornea, sclera (the “eye white”) and conjunctiva (the lining of the eyelids).
Like humans, dogs have an upper and lower eyelid - but they also have a third eyelid to help protect against scratches and to help produce saline. Dogs also have binocular eyesight, where the eyes are placed to the sides, rather than the front of the face, allowing for a broader range of peripheral vision.
Eye Differences Between Humans And Canines
There are also a few key differences in the makeup of the eye itself. The retina of the eye (in both humans and dogs) contains two central cell-types: cones, which discern between different colours - and rods, which help to detect movement and levels of light. These are attached to “ganglion” cells, which send information from photoreceptors to the brain. The brain then combines the impulses from the photoreceptors to interpret what the viewer is looking at.
While in dogs thousands of rods might be attached to a single ganglion cell, they have far fewer cones - but the human eye has an entire structure made up of cones called the fovea, which is used when reading. Dogs also have the capacity for wider pupil dilation, allowing them to see more clearly in low light conditions or when picking out moving objects, in addition to a lens placed close to the retina, which helps to make images appear brighter.
What Colour Eyes Do Dogs Have?
Like humans, the central coloured part of the eye in dogs (the iris) can vary, often appearing as brown, blue, hazel or golden in colour. Dogs can also appear to have heterochromia, or two differently coloured eyes. This phenomenon often occurs in certain breeds such as huskies or Dalmations.
Contrary to what some might believe, light or blue eyes is not necessarily an indicator of future sight-impairment or any other health condition. Iris pigmentation may also be dependent on factors such as face colouring, breed and genetics.
Do Dogs Only See In Black And White?
Another key difference between human and canine eyes is colour perception. The idea that dogs can only see black and white originally came from optometrist Gordon Walls, who in 1942 argued that dogs’ ability to see colour (if at all) was very weak. In 1989, this theory was debunked when ophthalmologist Jay Neitz, found that canines could see certain colours.
While humans have an entire structure made of cones enabling us to see many colours more vividly, dogs possess what is known as dichromatic vision. This means they have only two types of cones, allowing them to see blue and yellow. But what do dogs see when they look at other colours?
Are Dogs Colour Blind?
While both dogs and humans rely on neurons inside the retina to perceive yellow light (which excites neuron activity) and blue (which suppresses it), in dogs and humans who are red green colour blind (the other main type being blue-yellow), both red and green light have a neutral impact on the neurons - in other words, there is no way to identify either red or green.
While red might appear like a black or grey-brown hue to dogs, other colours might appear in varying degrees of yellow - while purples would more closely resemble blues. That said, according to a 2014 study there may be some evidence to support the idea that dogs can see colours that may be invisible to the human eye due to their ability to see higher levels of ultraviolet.
Sight, Smell - and The Canine Brain
While dogs might not be able to tell whether their favourite ball is green or red, they can certainly tell by using smell. By contrast to humans 5 million smell receptors, dogs have up to a bullion and can even communicate with other dogs via chemical signals, as well as being able to identify a smell from up to two miles away.
This incredible sense of smell might not appear connected to their eyesight, but in fact the two are inextricably linked, as a 2022 study published in the Journal of Neuroscience shows. In dog’s brains, the olfactory bulb (which processes smell) and the occipital lobe (which processes vision) are directly connected.
Can Dogs See Well In The Dark?
As descendents of primates, human eyes evolved to better identify the colours of berries and fruit (to see whether they were ripe or poisonous) during daylight hours. But what do dogs see when it's dark - and do they have “night vision”?
Canine eyes had to adapt in order to see well in low light when hunting at dawn or dusk - and for detecting motion - functions which also helped them to avoid potential threats. This is made possible using the tapetum lucidum, a mirror-like membrane composed of reflective cells underneath the retina.
What Causes The “Glowing Eye” Effect?
The tapetum(present in most, though not all dogs), combined with a larger pupil, rounder lens and a higher rod-to-cone ratio enables dogs to see better in dim conditions - and due to its reflective qualities also creates that “glowing eye” effect you may see in photos of your pet!
This combination of factors also creates a similar effect to the aperture of a camera on maximum exposure - so in dull, dim conditions, a dog may be able to get the maximum amount of light, but will only be able to focus on a small range of vision.
Are Dogs Near-Sighted?
While normal human vision is 20/20, the visual acuity of dogs is 20/75 - which means that an object visible by a human from 75 feet away would need to be around 55 feet closer in order for it to be visible to a dog. However: this does not apply to all breeds: labrador retrievers have eyesight that is closer to 20/20; hence their common use as service dogs for the blind or sight-impaired.
In most cases dogs are neither near or far sighted, with the exception of certain breeds including rottweilers, miniature schnauzers and German Shepherds, who according to a 1992 study tend to be more near-sighted. Sight differences in breeds can also depend on the number of ganglion cells across the middle of the retina (also known as a visual streak) enabling long-nosed dogs in particular to see better in detail.
Vision Checking For Dogs
Testing a dog’s eyesight involves simple tasks such as checking to see whether they can walk into a room via a doorway or navigating obstacles in bright or dim light. These dog eye examples are performed by veterinary ophthalmologists or dog eye specialists. Signs your dog has vision problems might include:
- Behaving in an anxious,clingy or aggressive manner in unfamiliar settings.
- Avoiding daily activities such as going for a walk.
- Clinging to or “hugging” the wall.
- Bumping into things.
The best way to protect your dog’s eyes is to offer them a healthy balanced diet and to make sure you take them for regular checkups at the vets. If you have any concerns about your dog getting the right nutrients needed for eye ehealth, such as omega 3 fatty acids and vitamin A, consult your vet before adding any pet-safe vitamins to their diet.
Treatment for Eye Problems
In the event that treatment is required, the dog may then be referred for treatment such as eye drops or in the case of more severe conditions such as development of cataracts , they may require surgery. Some breeds of dog are more prone to developing blindness than others, so this is something to be mindful of if you are considering adopting a pet.
Dog blindness is not uncommon as they age, and may lead happy lives so long as they are safe and comfortable. This may require some adjustments such as taking leashed walks, not leaving unusual objects in your pet’s path where they normally walk, gating staircases (blind dogs tend to have difficulty navigating stairs and fencing outdoor areas such as back gardens.
For more petcare advice, check out another of our articles here on the Pet Hub - or why not head over to our range of products, including a great range of dog leads and our dog crate selection.