Most dogs rely on the sense of smell. However, there are breeds that have been bred to better use eyesight. A good example is greyhounds whose task was to hunt fast-running hares. Sheepdogs can also see the slightest movement in a herd and react to it accordingly. Retrievers follow the flight path of the shot bird to find the place where it fell as soon as possible and bring prey to the hunter. Let’s think about how dogs see. Do they see the world as much as we do?
Dog’s eyesight – are they really worse than humans?
It is customary to say that the dog’s eyesight is worse than humans. This is not entirely true! Yes, the visual acuity of dogs over long distances is definitely less than that of a human. However, a canine vision has several properties that are lacking for human eyes. These include, among others, much greater sensitivity to light reaching the eye, i.e. the ability to see even in a very dark environment, and greater sensitivity to movement at the edge of the field of view. These differences result from other adaptations and the lifestyle of man and dog.
Does the dog see colors?
It was once thought that dogs do not distinguish colors at all and see the world only in shades of gray. However, as early as the 1980s, scientists at the University of California proved that dogs can distinguish certain colors. Both the dog’s eye and the human eye have two types of photosensitive receptors located on the retina. Suppositories allow you to see colors in good lighting, while rods allow you to see in a small amount of light. Man has three types of suppositories sensitive to red, green and blue. This gives us the opportunity to distinguish about ten million colors. On the other hand, dogs have only two types of suppositories that allow them to see shades of yellow and blue. Dogs perceive colors such as green, yellow and orange as different shades of yellow. Purple and blue see as blue, and red perceive dogs as dark gray or even black. Of course, in addition to the eye itself, nerves and the brain also take part in the vision process. Therefore, it is very difficult to clearly determine how dogs really perceive colors. However, knowing that their eyes are particularly sensitive to yellow and blue, we can use it in everyday life and buy dogs in these colors. The red ball against the grass will be less visible to the dog than the blue ball. In turn, buying a dog’s bright yellow clothes may not be the best idea. Such a pooch will be too noticeable and may become the target of other dogs’ attacks.
Seeing in the dark
Wild dogs are active mainly at dawn and after dark. No wonder that their eyes have a number of adaptations to see in the twilight. One of them is a large number of photoreceptors called rods, which are responsible for seeing shapes and movement even in low light. In addition, the dog’s eye is equipped with a reflective tapestry, which is located behind the retina. Its task is to redirect light rays to the retina, thanks to which the dog’s eye catches a lot more photons. It is thanks to the tapestry that the eyes of the dogs in the camera flash glow yellow or green. Our eyes do not have tapestries and glow red in the flash. Another adaptation to vision with a small amount of light is a relatively large surface of the cornea and a large lens that allows focusing a large amount of light.
Visual acuity
The large lens allows dogs to see better in the twilight, but this happens at the expense of depth of field. In addition, man has special muscles that can change the shape of our lens, adapting it to the sharp view of both near and far objects. Dogs cannot change the shape of the lens so efficiently, but they can use the muscles to slightly change the shape of the whole eye. Researchers at the University of Wisconsin’s Veterinary Medicine School examined 240 dogs of different breeds for visual acuity. It turned out that some breeds such as rottweilers, German Shepherd dogs, and miniature schnauzers have a predisposition for myopia. Rays of light passing through their cornea and lens focus in front of the retina, which causes the dog to see objects close by very sharply, while objects far away remain blurred. In turn, greyhounds are usually far-sighted, i.e. light rays passing through their cornea and lens focus behind the retina. Greyhounds can see objects far away better, and blurred ones relatively close. This is an obvious adaptation to hunting small animals.
Sensitivity to movement
Dog’s eyesight is very sensitive to movement. No wonder, since dogs are born hunters, perfectly adapted to hunting in the twilight. The dog can recognize a moving object even from a distance of a kilometer, while the same object still can ignore, even when it stands several dozen meters from it. Dog victims often die to become invisible to a predator. It is worth remembering and keep calm when dealing with dogs, do not make sudden movements and not run away from them. Such behaviors only incite them to even faster pursuit, and sometimes even to attack.
Due to the high sensitivity to movement, many dogs have problems with fast-moving objects such as bicycles or cars. These are stimuli that trigger a desire to rush or chase. Therefore, from the first weeks, it is good to get the puppies accustomed to such objects and teach them calm behavior in their presence. Dogs are great at recognizing people and their potential victims by the way they move. However, if someone moves similarly to us and is far enough that the dog does not see him too sharply, then a spectacular mistake is possible. My dogs have mistaken a plastic bag with a runaway cat many times. We can also use the dog’s sensitivity to movement to play together.
Field of view
Because of their height and moving on four legs, dogs see the world from a slightly different perspective than people. As bipedal, upright beings, we see much more than our dogs. This gives us a certain advantage in looking for different types of stimuli such as other dogs, cyclists or cats. We can also respond to these stimuli in advance, ahead of our dog’s reaction.
If you have a puppy at home or have a new dog, it is worth walking around on all fours and looking at the world from his perspective. This is the easiest way to locate objects such as pillows, protruding cables or other elements that may interest our pet, and which we would like to save from his teeth.
Understanding how dogs see the world is important in a shared relationship
The better we understand how dogs see the world, the better our relationship with them will be. Both people who care for their beloved dog, as well as dog trainers or athletes, should be aware of the way dogs perceive their surroundings. Thanks to this, it will be easier to help the dog find its place in our human world and build a deep bond with it.
0 Comments