Vision of dogs: what and how our pets see
Let’s start with an important and very interesting question: Do dogs distinguish colors. Many believe, based on old data, that dogs see our world in black and white. This is not true. According to the latest research by scientists from the United States, in dogs. color vision, but different from human. Why? There are fewer cones in the retina of a dog’s eye than in the human eye, and it is the cones that are responsible for color perception. The human retina contains 3 types of cones, each of which responds to a different range of colors. Some are sensitive to long-wavelength radiation: red and orange, others to medium-wavelength: yellow and green, and still others to blue, blue, violet colors. And the peculiarity of the retina of dogs is that they do not have cones that are sensitive to red, due to this, they cannot catch the difference between yellow-green and orange-red colors. This feature of canine vision is similar to color blindness in humans.
What a person perceives as blue-green, a dog can see as white. But dogs are much better than humans at distinguishing all shades of gray. This is not only because the retina of the dog’s eye has more rods, i.e. light-sensitive cells responsible for the quality of vision at dusk, but also due to the fact that the rods themselves are more sensitive than human ones. Thanks to this, dogs see at night at 3, maybe even 4 times better than humans. No wonder, they say that dogs are transitional animals, i.e. they are average between daytime and nighttime. Let’s try to conditionally divide the retina of a dog’s eye into 2 parts. upper and lower. The upper part helps to see better against a dark background due to the fact that there is a reflective membrane behind the photoreceptors of the upper part, therefore, light entering the eye is reflected by the membrane. These same reflected rays are immediately captured by cones and rods, and instead of one ray, two are obtained, as it were. The lower part of the retina contains a dark pigment that absorbs “unnecessary” light rays, and thanks to this the dog sees perfectly in bright light. Perhaps someone will have a question: who sees better, a dog or a man? The answer is simple. There are many differences in the structure of the human eye and the dog’s eye. For example, a person has a yellow spot in the eye that contains cones and is located in the center of the retina, on the optical axis of the eye. Light rays, straight, not distorted when passing through the cornea and lens, fall on the cones. The rods are found on the rest of the retina. Dogs do not have this spot, so their visual acuity is 3 times lower than that of a human. An interesting fact: if we wanted to check the dog’s eyesight using the checklist in the ophthalmologist’s office, she would be able to distinguish only the third line, and a person with good eyesight will be able to read the tenth.
Do not think that dogs are nearsighted; they, by the way, have a weak hyperopia, up to 0.5 diopters. rate of most adults. The thing is that, like all predators, a dog does not need visual acuity. Here it is more important to see equally well at any time of the day and to determine the object of the hunt. It is from here that dogs have the ability to see a moving object better than a stationary one: due to the larger number of sticks in the eye, a dog can see a moving object at a distance of 800-900 m, and a stationary one only from 600 m. The consequence of this is that you cannot run away from dogs. You will be perceived as prey.
Also, the dog can more accurately determine the distance. Perhaps this is due to the fact that the rods are located near the optical axis of the eye, where people have a “macula”. At close range, the dog sees vaguely, it needs a distance of at least 30-35 cm, and a person can focus on an object from a distance of several centimeters.
Can Dogs See Color? How a Dog’s VISION Works
An interesting question about the dog’s field of view, because it is also different from human. The human eye’s field of view is a circle, and the dog’s field of view is “stretched” to the sides. The axes of the eyes in humans are parallel, and in dogs such that the optical axes diverge by 20 degrees. It is thanks to this that the field of view of a dog is 240-250, and that of a person is 60-70 degrees less. These figures are given without taking into account such important characteristics as the structure of the skull, the location of the eyes and the shape of the nose. For example, in dogs with wide muzzles and short noses, the angle of divergence of the eyes is small, therefore, their peripheral vision is limited. Narrow-faced hunting dogs with an elongated nose have a large divergence of the eyes, therefore, their field of view is wide. It is believed that wild dogs have better eyesight. There is no exact data on this, but all wild animals have better eyesight. For example, the vision of monkeys is 3 times better than that of humans. And the number of rods in the retina of a wolf is higher than in a dog, therefore, their vision is sharper, although wolves, like dogs, do not distinguish red. Why do pets lose their eyesight? Animals living at home gradually lose the quality of vision, since they simply do not need it, they have nowhere to hunt.
Many people think that the main thing for a dog is the sense of smell, not the sight. But this is not entirely true, it all depends on the breed. For example, if a dog’s ears are standing, the main thing for her is hearing, but if they are hanging, the main thing is smell. To tell the truth, vision generally goes to the second, or even the third plan, dogs do not even recognize themselves in the mirror. For people, the main thing is sight. they receive almost all information about an object by examining it, in cats and dogs, on the contrary, the image of an object is formed mainly from auditory olfactory data, therefore, a standing odorless object does not exist for them. An interesting fact should be noted here: dogs are watching TV, or rather, they will soon be doing it. A person perceives the alternation of frames with a frequency of 50-60 hertz, and dogs over 80 hertz. New generation TVs have a frequency of 100 hertz, therefore, dogs will soon watch films on a par with us, especially since there are already several films specifically for animals.!
Dog vision and testing
It’s no secret that animals feel and see the world differently from people. At the same time, in order to better understand their pet and draw up more effective training programs, it is important for the owner, among other things, to imagine how dogs see, how they hear, what they respond best to, etc. After all, for example, what colors the dogs recognize depends on what shades the shells and aorting objects should be. Considering the importance of these issues, we decided to publish a series of articles devoted to the senses of animals. In this material, we are talking about what kind of vision in dogs, and we will talk about hearing and smell in the following publications.
How Dogs See: Color or Light
Many owners are interested in whether dogs see in the dark and is it true that dogs have black and white vision, and if not, how do they see the world? To answer all these questions, remember that, like you and me, our pets have special photoreceptors located in the retina of the eye responsible for color and light recognition: rods and cones. Only the number of these receptors and their set in humans and in dogs are different. therefore, we also see differently.
So, color vision is given by cones (they are also called the organ of daytime vision). There are not so many cones in dogs, so they in principle distinguish colors, but only to some extent. Thus, if you have two identical toys, while one is sky blue and the other is cornflower blue, then they will be almost the same in color for your pet, and the animal will distinguish them by other signs, for example, by smell.
We also note that a person has three types of cones: for the red-orange part of the spectrum, yellow-green and blue-violet. Dogs do not have cones responsible for red-orange colors, and this further narrows the palette: instead of the rainbow we are used to, they would see a transition from blue to yellow through white. That is, for dogs, the most contrasting colors are precisely blue and yellow, and this should be taken into account in training, for example, choosing colors for shells.
On the other hand, dogs have much better light (or night or twilight) vision. This means that animals need less light to determine the shape and size of an object, the speed and direction of their movement. Due to this, dogs see at night and at dusk much better than people: when objects merge with the darkness for us, our pets clearly see each of them and are perfectly oriented on the terrain.
Thus, the rods give good black and white vision with different shades of gray, and a small number of cones dilute the given palette with other colors. Therefore, to say that dogs see everything exclusively in black and white is still incorrect. Note that these features of the eyesight of dogs are associated with the fact that in the wild they are active, including at night, and from an evolutionary point of view, it is more important for them to see well in the dark than to distinguish color nuances.
An interesting fact is that the “glow” of dogs’ eyes is connected with the structure of the retina. The fact is that they, like other nocturnal animals, have another layer between the layer of rods and cones. of crystals and filaments. It reflects the light falling on it, which makes it seem to us that our eyes are glowing.
Features of dog vision: range and latitude
In addition to cones and rods, there are other receptors in the retina. fixing the movement of objects, the appearance or disappearance of a light signal, and other factors. However, the eye as a dog’s organ of vision only receives information, and its direct processing takes place in the head. in particular, the brain is responsible for the formation of a single picture from the data received from both eyes (recall that each of them looks “separately”, and only then images are aligned). In addition, from separate fragments obtained from views in different directions and when focusing on different objects, an integral picture of the surrounding space is compiled. The brain centers located in the occipital cortex are responsible for this work.
The fact that the vision of a dog and a person is binocular (that is, it is formed from partially duplicated data coming from two eyes) helps us to distinguish between reliefs, see in depth and determine the distance of an object from the eyes. At the same time, unlike humans, a dog has no central fossa in the retina, an area of maximum visual acuity in which cones are concentrated. For this reason, the animal does not make rapid eye movements following a moving object. your pet does not have such a need, since he sees well with the entire retina.
However, the absence of such a spot makes the dog’s vision less acute. So, she sees objects of average size at a distance of 100-150 m. This is not too far, but it does not matter for a dog, because it reacts much more sensitively to movements (which it is supposed to do as a predator). In particular, your pet perfectly distinguishes the movements of another animal or person, including perfectly reads the trainer’s gestures or his facial expressions. For comparison: a dog distinguishes a fleeing person at a distance of up to 400 m, and after certain training. up to 800 m.In turn, if a person does not move, then the dog may not notice him at a distance of 100 m until he detects by smell.
Of particular interest is the peripheral vision of dogs. In general, their angle of view is wider than ours, but the field in which the animals see best is narrower. This is again related to evolutionary development: the predator must look straight ahead and focus on prey. However, you should not completely lose sight of what is happening around.
Dog vision test
Like humans, dogs’ vision can deteriorate. from old age, injury, or various diseases. For example, in some animals, significant problems (up to complete blindness) arise from the plague. At the same time, often. again, like in humans. such problems are not reflected in the way the eyes look. Then how do you know if your pet sees well??
There are several simple techniques that every owner can try on how to measure a dog’s vision. First of all, pay attention to the behavior of the animal: a dog with normal vision is free to orientate in the surrounding space, does not bump into walls, corners and other obstacles. If your pet has problems getting through the door or bypassing an unexpected obstacle on the road, it is likely that his vision is failing.
To test if the dog is able to see, bring your hand to its eyes without touching the eyelashes and observe the reaction. If it does not follow, and the pupils do not respond to light (they do not expand when you block the light with your hand, and do not narrow when you remove it), then the animal definitely has serious vision problems.
Another test method: tie the dog up and move 10-15 meters away from it. Then call her and make a few familiar gestures for her or throw an object. A dog with good eyesight will react accordingly, but a visually impaired dog will not show any reaction.
Do not forget that you should always consult your veterinarian if you have any questions, suspicions or problems.
How Dogs See?
Any person who has got himself a shaggy four-legged pet looks into his intelligent loyal dog eyes every day. They understand almost everything, express joy or sadness, but they cannot tell the owner anything in words. What processes are going on in their heads? What color do dogs see our world around us? If you are reading this article, it means that you have also been interested in these questions more than once. Scientists have been studying dogs for a long time, and some of the data obtained as a result of long-term experiments will be somewhat unexpected for many people.
How many flowers does a dog see?
recently, we were assured that dogs see the world in black and white. This opinion turned out to be wrong. The color vision of our pets is somewhat different from that of humans, but still they cannot be called color blind. It’s just that these animals have a slightly different eye structure. The retina contains special cones that are responsible for color sensitivity. They are special for every living creature. Our four-legged friends do not have those who perceive the color red. Yellow-green tint with yellow-red tint they can be confusing. And a blue-green canvas for dogs in general may seem like a white sheet.
Do dogs see in the dark?
Scientists consider our four-legged pets to be transitional animals, which are well-oriented both during the day and at dark at night. Their light-sensitive rods are much better developed than those of humans. This allows dogs to distinguish more shades of gray. After sunset, most of us cannot see anything without a flashlight, but dogs continue to feel comfortable. It has been proven that at night their vision is 3 or 4 times better than human. The retina of our pets is divided into sectors. The lower sector absorbs excess light, which makes it possible for its owner to see well in bright light. And the upper sector is designed to enhance vision at night.
Dogs are predators, and it is very important for them to determine the object of the hunt at any time of the day. They are better at picking up a moving target than a stationary object. These animals are able to see your movement at a distance of almost 800-900 meters. But if the target lurks, then a sensitive four-legged watchman will notice it only from 600 meters. That is why dogs will quickly perceive a fleeing person as an object of hunting.
How do dogs see at close range? It has been experimentally proven that close things for dogs look somewhat vague. But people can easily focus on very close subjects. Our smaller brothers are not short-sighted, as some thought. They even have a slight hyperopia (about 0.5 diopters). Another difference between dogs and humans. in humans, the eyes are on the same axis, but in them. these lines diverge slightly to the sides, by about 20 degrees. These figures largely depend on the breed of the pet, the structure of the skull in different animals can be very different. Compare, for example, the head of a pug, a Pekingese, and a German shepherd. But in any case, the field of view of these animals will be slightly larger than ours. In our dogs, a holistic image is formed not only from what they see with their eyes, but in many respects it also depends on smell and hearing.
It is believed that in breeds with hanging ears, the sense of smell comes first. And in pets with erect ears (German shepherds and others), hearing is best developed.
We have already covered the question of whether dogs see colors. What picture do they perceive on TV? Our television receivers are designed for people. Their frame rate is such that these animals cannot see a normal image on the screen (for dogs, it should be at least 80 Hz). Instead of the film, Bobiki and Balls see one flickering. But here’s the new TVs with a frame rate of 100 Hz for our smaller brothers may be of interest. In the West, they even began to shoot special tapes for shaggy pets.
Many believe, and we are often presented, that domestic artiodactyls react sharply to red. In reality, the eyes of these animals perceive the color palette in very blurry fuzzy tones. Therefore, bulls and cows react more to movement than to how your clothes are colored or what color they wave in front of their face. I wonder who will like it if they start waving a rag in front of his nose, sticking, in addition, a spear into the scruff of the neck?
Features of vision
And yet, how do animals see? According to some indicators, animals have more perfect vision than humans, but it is inferior in the ability to distinguish between colors. Most animals see only in a specific palette for their species. For example, for a long time it was believed that dogs see only in black and white. And snakes are generally blind. But recent research has proven that animals see different wavelengths, unlike humans.
Thanks to vision, we receive more than 90% of information about the world that surrounds us. Eyes for us. the predominant sense organ. It is interesting that the vision of animals in its acuity is significantly higher than that of humans. It’s no secret that predators see 10 times better. The eagle is able to detect prey in flight from a distance of several hundred meters, and the peregrine falcon tracks the pigeon from a height of a kilometer.
The difference is that most animals can see perfectly in the dark. The photoreceptor cells of the retina in their eyes focus the light, and this allows nocturnal animals to capture streams of light in several photons. And the fact that the eyes of many animals glow in the dark is due to the fact that a unique reflective layer called tapetum is located under the retina. Now let’s look at certain types of animals.
Many nocturnal animals have large eyes. For example, tarsier. This is a little monkey that goes hunting at night. Its size does not exceed a squirrel, but it is the only primate in the world that feeds on insects and lizards.
The eyes of this animal are huge and do not turn in the sockets. But at the same time, the tarsier has a very flexible neck that allows him to rotate his head 180 degrees. He also has extraordinary peripheral vision, allowing him to see even ultraviolet light. But tarsier distinguishes colors very poorly, like all nocturnal animals.
I would also like to say about the most common inhabitants of cities at night. bats. For a long time, it was assumed that they did not use their eyes, and only fly thanks to echolocation. But recent studies have shown that they have excellent night vision, and more. bats are able to choose whether to fly for sound or turn on night vision.
Many houses keep animals, and the most common, of course, are cats. The vision of animals, and especially of the feline family, differs significantly from that of humans. A cat’s pupil is not round, like most animals, but elongated. It reacts sharply to large amounts of bright light by narrowing down to a small slit. This indicator says that in the retina of the eyes of animals there is a large number of receptor rods, due to which they see perfectly in the dark.
The gracefulness of the horse and its expressive eyes can hardly leave anyone indifferent. But often, those who learn to ride are told that it is dangerous to approach a horse from behind. But why? How do animals see what is happening behind them? No way. the horse has a blind spot behind his back, and therefore he can easily get scared and kick up.
Let’s add some anatomy. In the retina of any living being, there are two types of receptors: cones and rods. Color vision depends on the number of cones, and the rods are responsible for peripheral vision. In horses, the number of rods prevails over that in humans, but cone receptors are comparable. This suggests that horses also have color vision.
How do animals see? What colors are distinguished?
Eyes. it is a special organ that all living beings on the planet are endowed with. We know in what colors we see the world, but how do animals see it? What colors do cats see and which ones do not? Is vision black and white in dogs? Knowledge about the vision of animals will help us take a broader look at the world around us and understand the peculiarities of the behavior of our pets.
Talking about how animals see, one cannot remain silent about how they see snakes. The tale of Mowgli, where a boa constrictor bewitches monkeys with its gaze, is awe-inspiring. But is it true? Let’s figure it out.
Snakes have very poor eyesight, this is affected by the protective shell that covers the reptile’s eye. From this, the named organs seem cloudy and take on that terrifying appearance, about which they make up legends. But vision for snakes is not the main thing, basically, they attack moving objects. Therefore, the tale says that the monkeys sat in a daze. they instinctively knew how to escape.
Not all snakes have some kind of heat sensors, but they still distinguish between infrared radiation and colors. The snake has binocular vision, which means it sees two pictures. And the brain, quickly processing the information received, gives it an idea of the size, distance and outlines of a potential victim.
Dogs’ vision is different from what we are used to. If we return to anatomy again, then in the eyes of a person there are three types of cone receptors:
- The first one perceives long-wave radiation, which is distinguished by orange and red colors.
- Second. medium wave. It is on these waves that we see yellow and green.
- The third, respectively, perceives short waves, on which blue and violet are distinguishable.
The eyes of animals are distinguished by the presence of two types of cones, so dogs do not see orange and red colors.
This difference is not the only one. dogs are farsighted and see moving objects best. The distance from which they see a stationary object is up to 600 meters, but dogs notice a moving object from 900 meters. This is the reason why it is best not to run away from four-legged guards.
How Dogs See The World — And It’s Than Black And White
Sight is practically not the main organ in a dog, for the most part they follow smell and hearing.
Now let’s summarize. what colors do dogs see? In this they are similar to color-blind people, they see blue and purple, yellow and green, but the mixture of colors may seem to them just white. But best of all, dogs, like cats, distinguish gray colors, and up to 40 shades.