Dogs can make great family pets. Some dogs seem to be more active and agile at night than others. How good can your dog see in the dark? Do they need a nightlight to help them see at night? Can dogs see in the dark? Dr. Jess explains the answer and more below:
Dog Basics 101:
Dogs, also known as canines, pooches, pups, doggies, etc., are a very popular pet in the United States.
Canines were first domesticated over 13,000 years ago, and have been in our homes and hearts ever since.
Dogs can range in size from 2 pounds to over 200 pounds. Some can fit inside your cupped hands, while others can barely fit inside a vehicle.
Some dogs are compact, with extra wrinkles and smoochie-faces, also known as being brachycephalic. Other dogs are long a lean, with pointed ears and noses and stealthy-lean bodies. And there is anything and everything in between!
Then we get to coats…. there are different coat colors, coat lengths, and coat textures. Some dogs shed their fur, while others do not. Some dogs require daily grooming, while others need a bath or a brushing every once in a while.
In captivity and with proper care it is quite common to see these pets live up to 8-10+ years of age depending on a ton of different qualities and factors.
Some dogs are quite hyper and active, while others are calm and lazy, while still others are the working-type, being protective or feeling needed by having a job to tend to.
Many dogs are used in the workforce today – from police dogs, to herding dogs, to medical alert dogs – dogs are very needed in our society.
They are very caring, playful animals and desire to socialize with the ones that they know and love.
They make great pets for responsible pet owners, wanting a loveable pet and companion that can come in a multitude of packages.
Dog Eye Basics:
Dogs are born with two eyes, with the exception of dogs who are born or who have their eyes removed for medical reasons.
Dog eyes are a lot like human eyes in how they are designed and how they work.
The outside of the eye is called the cornea and can be easily scratched by dog nails and other hard pointy objects. The cornea is transparent to the naked eye and must be lubricated by the eye and eyelid to stay healthy.
The white part of the eyeball is called the sclera and the colorful part of the eye is called the iris.
Canines can have different colors of iris. The most common color of iris is brown, but other colors can occur.
The iris is in charge of letting light into the eye, by making the pupil, the black circular section in the middle of the eye, smaller or larger depending on the need for more or less light into the eye.
The pupil dilates (gets larger) to let more light in, and the pupil constricts (gets smaller) to let less light in.
The lens is behind the iris and helps to send the light to the retina at the back of the eye.
The retina has many photoreceptors and will send the information it receives to the optic nerve and on through to the brain to process what the eye is seeing.
The Merck Vet Manual has a great image of the structure of the dog’s eye.
The eye is surrounded by soft, moist, pink tissue called conjunctiva to help protect and cushion the eye and an upper and lower eye lid also help to protect and guard the eye too.
The surrounding tissue also contains tear ducts that release tears onto the eye’s surface to help clean, flush out, and lubricate the surface of the eye.
The tears of the dog contain multiple substances, including enzymes that help protect the surface of the eye from invaders, such as certain bacteria.
Dogs have an upper and lower eyelid surrounding each eye that is used as protection and to help spread the lubricating tears to the surface of the eye.
Because of these eyelids, dogs have the ability to wink!
How Does an Animal See? Eye Function:
Pretty much all animal eyes work in the same basic manner. Light is allowed in the eye in various degrees, depending on the eyes structure and adaptations, which can differ depending on the animal in question.
The light is brought into the eye and onto the retina at the very back of the eye.
The retina has many photoreceptors and will send the information it receives to the optic nerve and on through to the brain to process what the eye is seeing to form a picture for you of what you are observing.
What Allows Animals to See in the Dark?
Owls and other animals with excellent night vision have special adaptations that help them see well in darker environments. These are a few physical attributes that these animals have that help them see so well in the dark:
Tapetum lucidum:
The tapetum lucidum is a very thin, reflective surface behind the retina in the back of the eye.
It’s beautiful shiny, reflective surface allows light to reflect back into the eye after it’s passed through its original attempt.
So there is a second shot at retrieving the proper amount of light the eye needs in order to achieve the light that it needs.
Rods & Cones:
The cones in our eyes allow us to see different colors, or wavelengths of light. The more types of cones (color receptors) one has, the more colors that one can see.
One extreme example of an animal with many cones, is the mantis shrimp, which has 16 types of cones in their very independent eyes.
This shrimp’s color receptors (AKA cones) allow them to pick up on small changes in color that their predators may not, allowing them to flee from danger more easily.
In fact, their eyes are so independent, that they can move independently of one another, much like a chameleon can move its eyes.
Pupil Shape:
Certain wild animals like wild cats, foxes, and even snakes, have vertical slit-shaped pupils that allow them to better see at night and have better depth perception too.
How Well Do Dogs See?
Dogs do not have the best vision around, but they also do not have the worst. Let me dive a little bit deeper here and get more specific.
Peripheral Vision:
Studies have shown that dogs have 250 degree eyesight. [source]
250 degree eyesight means that they have fairly good peripheral vision. It helps that they have forward-facing eyes that are set more on the sides of their head than a humans – making it easier for them to spot movement from the sides of their bodies, protecting them from danger from more angles.
Their eyes, which are set on the sides of their head, are placed purposely off to the side of their head in order for them to have better peripheral vision, much better than us humans!
Color Vision:
Canine studies show that dogs can see some colors, but to what degree that they can see colors is still debated, depending on what study or research you are trusting.
For the most part, most can agree that dogs can definitely see colors such as yellows and purples, but to what degree that they see other colors, is still undetermined.
Depth Perception:
One area where dogs do not do well with is in the depth perception department.
They have quite poor depth perception, compared to a human. For example, when compared to a human having 20/20 vision, a dog has more like 20/75 or 20/80 vision.
This means that something that a human can see in focus at 75 or 80 feet, a dog has to be at 20 feet in order to see the same thing at the same clear focus.
Moving farther away, means that the dog’s view of what their eye is focusing in on, will start to become more and more blurry, the farther they move away from that object.
Because of this poor depth perception, dogs must use other perks in their eyes and other senses, which are much more reliable, so survive and to help them move about, espcially in the dark.
Can Dogs See in the Dark?
Well, one thing that is widely known, is that light is needed to see in the dark.
No animal can see anything in complete lack of light or complete darkness.
For an animal to see, light enters the eye and then is sent to the back of the eye, where receptors transfer what was seen through the optic nerve and then on to the brain to be processed into a picture of what the being is “seeing”.
It’s a process with many steps that happens in less than a split second. But it all starts with at least a little bit of light.
Therefore, it is safe to say that dogs can not see in complete darkness.
But then there is the debate on how well they can see in dark or darker environments…
Dogs can see better in the dark than humans do. They have multiple adaptations that other animals and humans, do not have that help them to see well at night.
Here are the major adaptations that dogs have in order to see well in the dark:
- Pupil Size: The canine eye has a larger pupil than many other animals, including a human’s pupil. Remember, the pupil allows light to enter to the back of the eye. So if an animal has a larger pupil, then more light can be allowed to enter the eye, which is important in seeing in the darkness.
- Tapetum: A dog’s eye contains the tapetum lucidum, the reflective surface that you may notice reflecting in your dog’s eye when it’s dark out.
- Lots of Rods: Dogs do not have many cones in their eyes (in charge of seeing colors) but they do have many rods (differentiates in low light situations), which help them visualize in low-light settings.
Dogs also rely on other senses to help guide them at night so that they can move about and sleep safely.
Senses to Help Dogs ‘See’ at Night:
Sense of Smell:
Dogs have a great sense of smell. This sense of smell can help them to help them “see” at night when combined with other senses and adaptations discussed below.
Whiskers:
Vibrissae, also known as facial whiskers on animals, can very similarly to cat or rabbit’s whiskers it is thought.
These whiskers help your dog measure distances and figure out shapes that they can sneak in and out of even when they can not see well.
If their whiskers get bumped, your pooch will know that something is nearby their face. These whiskers help them to “see” better in the dark.
Spatial Memory:
Dogs have a good sense of direction. They have this impressive sense of direction because they have good spatial memory.
Spatial memory is a termed used to describe when a being is able to remember where things are placed or where routes of traveling occur, a mental map of where things are located in their little world.
What Animals Can See Well in the Dark?
To see well in the dark, some animals have special features that allow them to be better equipped for darker environments than other animals.
Other animals, unfortunately, do not have good eyesight at night, like the guinea pig, and must rely on other senses to get them through these darker hours.
For instance the owl has a few adaptations that make it very easy for them to see extremely well at night.
For starters, they have tubular-shaped eyes that are quite large for their bodies when compared to other animals of similar size.
Their eyes are also much more sensitive to light due to the large number of rods in their eyes (retinas) and the fact that they also have the tapetum lucidum to help them see at night as well.
Also, the way that their iris in their eye can adjust, the iris can widen a lot to allow even more light in at night than most other beings – remember, no matter if it seems dark out or not, light must enter the eye in order for anything to “see” in the dark.
Animals can not see in complete darkness because of the lack of light!
Sharks are another animal that can see well in the dark… and in the water too! This is because they have the tapetum lucidum to help them out as well.
Another animal with amazing night vision is the frog. Frogs can see colors in very very dark environments, far better than us humans or most other animals ever could imagine, because of the contrast that they see due to differing types of rods in their retinas!
Do Dogs Prefer to Sleep in the Dark?
Dogs are crepuscular by nature, meaning that they are most active at dawn and dusk, when the sun is either rising or setting.
But just because they tend to be active at dawn and dusk, does not mean that they do not like to sleep in the dark.
The typical dog does like to sleep in the dark.
The darkness allows them to feel more protected and safe because it is harder for predators to see or find them.
And this ‘safe’ feeling has been passed on from the wild dog, onto the domesticated dog that we bring into our homes and call our pet.
Do Dogs Sleep With Their Eyes Closed?
Some animals are more likely to sleep with their eyes open, usually because of innate protective mechanisms brought on by years of their ancestors surviving out in the wild, such as rabbits.
Dogs can sleep with their eyes open, even though not all pups will sleep with eyes open.
Some dogs will sleep with their eyes open when they feel that they need to stay alert and ready to flee at any given second. This is important for wild dogs, but not so much for domesticated pet pups.
When a dog becomes more comfortable with their surroundings, then they may someday close their eyes, or at least partially close their eyes, when sleeping.
Summary:
Dogs can see in the dark, but they are not the best in the animal kingdom at it. That is why dogs have adapted their eyesight to better see in low light and also use their other senses, to help them maneuver and navigate in dark settings.
These senses and adaptations, such as great smell and good hearing, as well as whiskers, help make dark environments easier to “see” in.
Not all of a dog’s sight in dark situations is done with their eyes.
Because most dogs can easily navigate their surroundings without light, it is not necessary to provide them with artificial light or night-lights at night in their environment.
They do just fine without any help!
If you are worried about your dog’s eyesight, contact your local loved veterinary immediately to discuss further exploration into the issue.
The information provided in this article is not a substitute for professional veterinary help.