Dogs have long been known to be able to see at night, but some breeds are better equipped than others. What makes a dog’s eyesight special?
Dogs do have night vision. Dogs have evolved over time to become highly specialized hunters. They possess excellent vision, allowing them to detect movement even at night, have a keen sense of smell to help them track prey, and their acute hearing allows them to hear approaching predators.
Today we look into the anatomy of a dog’s eye, as well as answering some questions about a dog’s ability to see in the dark.
The anatomy of the canine eye
A dog’s eyes consist of a number of working parts: an outer layer called the cornea, the middle iris, pupil and lens, and an inner part called the retina.
These structures are made up of layers of cells that help form light-sensitive tissue.
The cornea is located at the front of the eye and serves as the main refracting surface. Light enters the eye through the cornea and is transmitted through the pupil.
The pupil is controlled by the iris in terms of its color and size. These two factors can determine how much light enters the eye and therefore how well the dog can see in the dark.
The light travels through the pupil to the lens so that it can fine-tune the image, before moving to the retina. Here the light will be converted to electrical signals and sent to the visual cortex in the brain.
The retina houses a number of rods and cones, better known as photoreceptor cells.
These allow the eye to convert light into nerve signals, allowing the eyes to see and the brain to process what is in front of us.
Rods are better used in low lighting to see motion within darkness, while cones are more effective in bright light.
This is the same way that a human’s eye detects and recognizes light, so what’s so special about a dog’s eye?
How dogs have night vision
You might have noticed when you’re on a late night dog walk, that your dog seems to be much more alert and sensitive to movement than you are.
While you might not be able to see another person walking towards you until they’re only a few yards away, your dog could have alerted you much sooner.
There are a few reasons why dogs have better vision than humans, so let’s look at these in more detail.
Tapetum lucidum
This is due to their eyes having a tapetum lucidum, which is a number of reflective cells within the eye.
These cells act as a mirror behind the eye and can reflect light while enhancing it even in lower light conditions.
Humans don’t have a tapetum lucidum, meaning that we have to wait a little longer for our eyes to adjust to the darkness. Even then, we won’t be able to register movement in low light as quickly as dogs can.
Flicker fusion frequency
Another reason why dogs are able to see so well in the dark is due to a more powerful influence of Flicker Fusion Frequency.
This is otherwise known as how quickly intermittent frames of light are interpreted as a continuous picture.
Dogs have a higher FFF than humans, meaning that we see motion differently. For example, a television picture will be a continuous motion to us, while it will be flickering for a dog.
FFF also allows dogs to detect slight movement in darkness better than humans can.
Larger pupils
There is plenty of research showing that larger pupils allow more light in and therefore means that there is better potential for night vision.
As dogs have larger pupils than most humans, it means that dogs can see better at night.
The pupil dilates and contracts to determine how much light can enter the eye. The larger the pupil is, the more it is able to dilate and let even more light in.
This means that a dog’s eye can let more light in than a human’s eye, allowing them to see better at night.
More rods in retina
We mentioned earlier about eyes having rods and cones in them, and rods being more effective for seeing in low light conditions.
Dogs have a more rod-dominated retina than humans, allowing them to see much more effectively at night.
This is true for most animals, and the photoreceptor cells are better targeted towards seeing in poor lighting.
Dogs will be able to see shapes and motion much clearer at night than humans can, thanks to the more rods in their retinas than cones.
Interesting fact – Although dogs are able to see a spectrum of colors, they can not distinguish between the colors red or green. Dogs are also unable to pick out shades containing these colors such as pink, purple or orange. To find out more about the colors your dog can see, check out this informative blog.
Position of eyes
Finally, dogs have a wider range of view than humans do, due to the fact that their eyes are positioned towards the side of their heads. Of course, this is dependent on their breed.
A Great Dane will have a wider range of vision than a Cavapoo, due to the position of their eyes and their lack of thick fur surrounding their eyes.
Why do dogs’ eyes glow in the dark?
If you’ve ever been out with your dog at night, you’ll probably notice that his or her eyes glow in the dark with a greenish tint whenever they come into contact with light.
The light could come from a torch, a camera flash, headlights, or something else.
This greenish glow is actually from the tapetum, as the cells are reflecting the light back to the source of the light.
If you ever take a picture of your dog in the dark and their eyes glow green or yellow, now you know why!
Final Thought
So, what does all this mean? Well, it’s pretty obvious that dogs have an advantage over humans when it comes to night vision.
They’re able to see things much better in the dark than we can, which makes sense given how many benefits their eyes hold compared to humans!
Some things that help dogs see better in poor conditions are more rods in their retinas, a reflective layer of cells behind the eyes, and the positioning and size of their eyes.
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