Can Dogs See in the Dark?
Hopefully, they at least fare better than we do when the lights go out.
Dogs have a remarkable ability to see in low light, but their vision in complete darkness is limited. Despite not having true night vision, dogs possess other heightened senses which aid them in navigating in the dark.
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opens in a new tabWhy dogs can see in the dark
Dogs have adapted over time to be able to see well in low-light situations. Dogs cannot see anything in total darkness — no animal can see without light — but they still maintain vision when it might appear impossibly dark for a person.
Cats can see details in environments six times darker than what appears completely black to humans. Dogs land somewhere in the middle, possessing night vision superior to ours but not quite matching the impressive capabilities of felines. Dogs evolved the ability to see well under low-light conditions but maintained solid daylight vision as well. This gives them the ability to track objects in most natural conditions, so they are not limited to hunting during a particular time of day.
Understanding dog vision
Tracking the path of light as it enters a dog’s eye can help you to understand how they see and what adaptations have helped improve their night vision. As light enters your dog’s eye, it encounters the following structures:
Cornea
The clear surface of the eye is actually a very specialized version of epithelium (or skin). Its large size and domed surface allow light to enter from different angles. Many of the most common eye problemsopens in a new tab in dogs originate here.
Anterior chamber
This area in the front of the eye is filled with aqueous humor, a clear liquid that allows light to pass through. This liquid exerts pressure on the cornea and helps give the eye its shape. Inflammation in this chamberopens in a new tab can reduce that pressure.
Pupil
The size of this open space is controlled by the iris, which opens and closes to allow more or less light in. The pupil gets larger in low-light conditions so that the amount of incoming light is maximized.
Lens
This clear disc allows light to pass into the back half of the eye. It can change shape to focus the light on the very back of the eye, where the light-sensing tissues are. Cataracts develop hereopens in a new tab and can decrease the amount of light entering the eye.
Posterior chamber
The back part of the eye is filled with clear, jelly-like vitreous humor. This also helps maintain the shape of the eye and carries nutrition to some of the tissues of the eye.
Retina
This is where the magic happens. The retina is covered in rods and cones, which are specialized light receptors. Rods are great at picking up very faint light but don’t provide great visual detail. Cones need more light to function but are better at determining information about color and detail.
Tapetum lucidum
Sitting behind the sensory cells of the retina, the reflective tapetum lucidum bounces light that was not picked up by a rod or cone back at those cells for a second chance at stimulating vision.
Why dogs can see in the dark
Now that you understand how dog vision works, it’s easier to spot the different adaptations that allow dogs to have good night vision. Their corneas occupy a much larger area of the eye’s surface than people’s, allowing more light to enter. Their pupils can open wider as well, meaning that more of the light that enters is transmitted to the retina.
A dog’s retina has a higher proportion of rods than cones, giving priority to low-light vision. These rods are also located in the area of the retina that is most likely to be hit by light, increasing the chance that they will be activated. The tapetum lucidum reflects the light that’s missed by the rods and cones back at them, improving low-light vision at the cost of some visual acuity.
The increased number of rods and their location mean that dogs have evolved to prioritize seeing something in low light over seeing sharply and colorfully.
What colors can dogs see in the dark?
It’s not known for sure what colors dogs can seeopens in a new tab in the dark, but it’s likely that their low-light vision is not very colorful because of the relatively high numbers of rods providing visual information. Cones, which are responsible for color vision, take several hundred times the amount of light to activate than rods do. In very low-light situations, dogs likely see primarily in greyscale. As light levels increase, they likely see increasing amounts and varied shades of blue and yellow, which are the primary colors their cones detect.
Dogs vs. humans: Better night vision explained
Can dogs see better in the dark than humans? Yes, dogs have superior vision to humans in the dark. This is because people’s eyes have some key differences from dogs’ eyes, such as:
Smaller corneas
Smaller pupils
Relatively more cones than rods
Increased cone density in the central area
No tapetum lucidum
These differences make it harder for people to see in the dark. Humans do have some advantages, though: they’re able to see more colors and have superior rapid visual responses—as long as there’s enough light for them to see.
Dogs vs cats: night vision differences
Can dogs see in the dark like cats? Yes, but cats have even better vision in the dark than dogs do. The tapetum lucidum in a cat’s eye covers more area and is more reflective than a dog’s. As crepuscular animals, cats’ eyesopens in a new tab evolved to allow them to hunt best at dawn and dusk, when light levels are low.
A dog’s eyesight can be considered more balanced, allowing them some advantages over cats in full light, but some disadvantages in low light. Both dogs and cats see better in the dark than people do. It’s likely that your dog is very confused about why you didn’t see that table you stubbed your toe on when you’re stumbling around at night.
Breed impacts on night vision ability
Dog breeds likely have different visual abilities, both in how wide they’re able to see and how well they’re able to see at night. The differences in head shape between, say, a Pug and Greyhound affect their ability to focus and their field of view. In general, dogs have a wider field of view than humans due to the placement of their eyes. Humans usually see a range of about 180 degrees, meaning that they see primarily in front and to the sides. Dogs have a wider visual range, spanning about 240 degrees. This means that they can see a little behind themselves as well. Flatter-faced breeds likely have a broader visual range than long-nosed breeds, but at the cost of some depth perception.
Some dog breeds, especially toy breeds, have a less developed reflective layer in the back of their eyes as well. Dogs may also have degradation of their reflective tapetum with age. These factors will worsen their ability to see in the dark, though their night vision will still likely be better than a human’s due to the other adaptations dogs’ eyes have.
Evolutionary advantages of enhanced night vision in dogs
While it may seem unfair that dogs can see so much better than humans at night, it’s important to understand that human and canine vision evolved to solve different problems. Dogs are low to the ground and great at seeingopens in a new tab small motions in dark foliage, but humans excel at focusing on objects that are further away and differentiating them from their surroundings. The visual abilities of dogs and humans complement each other well, and they make a great pairing when used together, helping dogs to become man’s best friend.
FAQs (People also ask):
Why do my dog’s eyes glow at night?
A specialized layer of cells in dogs’ eyes called the tapetum lucidum reflects light back at the light-sensing cells if it’s missed the first time through. Some of the light that’s not picked up by them will exit the eyes, making them appear to glowopens in a new tab.
Are dogs okay being in the dark?
Dogs are usually fine being in the dark when it’s time to rest but may appreciate a little light to make it easier to get around. Things are less scary for them when it’s easier to see.
Can dogs see in the dark better than humans?
Dogs can see in the dark better than humans due to a variety of differences in the structures of their eyes. They have adapted to being able to see well in low light at the cost of some visual accuracy.
References:
Dynamics of the Normal Aspect of Tapetum Lucidum at Dogs Regarding Ageopens in a new tab
Explaining the Functional Differences of Rods Versus Conesopens in a new tab
Macroscopic and Histological Variations in the Cellular Tapetum in Dogsopens in a new tab
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