Many dog owners wonder if their pooches can see well in the dark, how a dog's eyesight compares to a cat's or a human's, and why their dog's vision might be better or worse than their favorite people's vision.
In this post, we'll explore the anatomy of a dog's eye and the advantages they have over humans when it comes to seeing in the dark.
How Well Can Dogs See in the Dark?
While dogs can see well in low lighting, their vision is not the same as humans. To understand your pup's vision, remember that they evolved from wild canines, which were active mostly at dusk and dawn. To track and catch their meals, they needed to be able to spot movement in dim light. Dogs have retained this advantage of seeing well in the dark while adapting to being able to see in broad daylight.
Many dogs have worse depth perception and see fewer colors than their owners. They also have less visual acuity, which keeps them from seeing some finer details, and less visual perspective since they are low to the ground. However, they can see very well in low lighting, and are better than humans at detecting light and movement in the dark (and other low-light situations).
Below, we'll get into more detail about how the anatomy of a dog's eye, including the tapetum lucidum and the light-sensitive rods in the retina, helps them see at night.
What Helps a Dog See at Night?
Dogs have several ways of forming an image of their surroundings at night. Since dogs do not have a large number of cones in their retina to pick up brightness and color, their eyes rely on these features for night vision:
- Depth perception
- Color perception
- Form and shape sharpness
- Motion detection
- Light sensitivity
- Visual acuity
- Visual field of view
- Visual perspective
Dog Eye Anatomy
Your dog's eye is comprised of the outer cornea, the middle iris, lens and pupil, and the inner retina. Each of them have specific roles to play in your dog's vision.
Cornea - This transparent shield focuses and transmits light through the pupil (which is controlled by the colored iris) to the lens. The image is then further fine-tuned or focused before it's sent to the retina, where light is converted into electrical signals and transported to the brain (visual cortex) along the optic nerve.
Retina - Holds specialized photoreceptor cells called cones and rods. Cones and rods allow or dog (or people) to convert light into nerve signals that ultimately power our vision.
Rods - Work better in dim lighting and help your dog detect shape and motions, while cones function better in bright light. Cones have a greater sensitivity for detecting color, clarity, and sharpness.
Can Dogs See Better in the Dark Than Humans?
You might be surprised to learn that dogs see better in the dark than humans. They have a few natural advantage over their people when it comes to looking for prey (or the perfect spot to go to the bathroom) in the dark. These advantages include:
Larger Pupil Size - You can thank your dog's large pupil size for that puppy dog eye look, as their pupils are significantly bigger than most humans'. The pupil dilates and constricts to control how much light enters the eye. The larger the pupil, the more light entering the eye, which means more potential for better vision.
Tapetum Lucidum - This reflective tissue is found in most mammals and causes the eye sheen you see in pictures of your dog or when you look into their tyes at night. Located just beneath the retina, the tapetum lucidum acts as a kind of mirror that reflects light onto the retina, allowing your dog to use less light, more efficiently.
Rod-dominated Retina - Dogs and most other domestic mammals have rod-dominated retinas, meaning most of their photoreceptor cells are best for seeing at night rather than during the day. Shape identification and motion detection are also better at night. Wolves probably have even greater nocturnal vision, since their retinas contain a greater ratio of rod-processing cells.
Along with these advantages, a dog's ability to detect motion at further distances is far better than ours. This is probably even true in dim light - an explanation for why dogs are better at catching and chasing than they are at playing hide and seek with their favorite toddler.
Can Dogs See Better Than Cats at Night?
Cats are known for having great nocturnal vision and can see even better than dogs in the dark. Kitties are much more sensitive to light, and their tapetum lucidum relects significantly more light. The vertical slit in a ca's pupil not only protects the retina in bright light, it also allows more light to enter the eye in the first place.
Why Do Dogs' Eyes Glow in the Dark?
Dogs' eyes sometimes take on a yellow-green glow when light from a camera's lens, flashlight or car's headlight hits them at night. In these circumstances, the color of the tapetum reflects light back and forth and can vary from blue or green to an orange or yellow hue. This coloration often changes over a dog's first three months of life.
Some dogs, often those with blue eyes, don't have a tapetum. That's why you'll often see red eyes, due to the red blood vessels at the back of the dog's eyes, rather than the greenish-colored reflection from the tapetum.
Should I Leave a Light on For My Dog?
Even with the advantages their exceptional vision affords them, dogs still need some light to see, since light stimulates their photoreceptor cells. While they can still navigate their surroundings better than humans in total darkness using their other senses, they will not be able to see. While it's rare for them to be in complete darkness, it's helpful to leave a nightlight on so your dog can see better at night.
Where Should I Go If I Think My Dog May Be Having Problems With their Eyesight?
Dogs sometimes develop minor or severe eye conditions or infections that can affect how your pup sees and cause pain or discomfort. While some conditions are related to age, others are diseases or injuries.
Regardless of the problem, any suspected loss of sight or discomfort in either eye should be promptly assessed by a veterinarian or veterinary ophthalmologist. Early diagnosis and treatment play an integral role in positive outcomes for your dog's health.
Animal Eye Guys's board-certified ophthalmologists work with your pet's primary care veterinarian to provide the most comprehensive and compassionate eye care possible. We're able to diagnose and treat virtually any eye condition or disease, including dry eye, infections, tumors, and more.
Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.