Do dogs only see black and white? Can my dog see well at night? Does my dog see better than me? What is the difference between dog eyes and human ones?
The dog’s eye raises many questions that we want to answer here. The eye is an important sense organ to perceive the environment. It is very similar to the human eye, only the colour spectrum, the field of vision and the movement vision differ. So how do dogs see now?
Structure of dog eyes
A healthy eye has many mechanisms to protect the sensitive sensory organ. The eyeball sits in the bone cavity of the head surrounded by a layer of fat and is protected by the two eyelids. Unlike humans, dogs have a nictitating membrane, the so-called “third eyelid”, which is visible in the inner corner of the eye and serves as a kind of windscreen wiper to remove foreign substances. The eyelashes catch small dirt particles. The clear tear fluid moistens the cornea, flushes foreign substances out of the eye and protects it from infections.
As it moves
Everything which moves is particularly well noticed by our four-legged friends. They can detect even the smallest movements, but they detect static objects more difficult and blurred. As soon as something moves, they perceive it very well and see sharply. This function is especially important for hunting. Dogs are hunters by nature, which is why they follow instinctively moving things. These symbolize the fleeing prey.
Visual field
The eyes are, as the human ones, directed forward, but are further apart. This means that the dog’s field of vision does not measure 180° as with ours, but about 240°. This gives them a better panoramic view. However, the spatial perception is thereby restricted.
Visual acuity
Dogs do not perceive the image of their environment precisely, but as a somewhat distorted image. The ability of accommodation (focus) is lower, so the dog sees things closer than 40cm in his environment blurred. They can see moving things sharper than still ones
Colours
Dogs see the world less colorful than humans, but they can distinguish the colors blue, yellow and violet well. Red and green, on the other hand, cannot be recognized. You can imagine it like a person with red-green vision loss. Different shades of grey can be much better differentiated by the dog. Suppositories are responsible for colour vision, of which dogs possess less than we do.
The rods, on the other hand, are responsible for the sensitivity to light. Dog eyes have more of these. In addition, there is a kind of mirror surface that lies behind the retina. The so-called Tapetum lucidum, which reflects the smallest incident light in order to be able to see better in darkness or poor visibility (fog, twilight).
Breed-related differences
Brachycephalic breeds (short snout) have more frontal eyes and are often more prominent than in long snout dogs. As a result, the eyes are less protected and thus more susceptible to injury or inflammation. Similar to us humans, short snout dogs see sharply at the so-called “yellow spot” on the retina. This enables them to see things directly in front of them sharply and can fix them better than objects further away. Movements and things in the corner of the eye (at the edge of the field of vision) are perceived with restrictions. Long snout or narrow-headed dogs have a stripe across the entire retina, which enables them to see sharply even at a greater distance, which is especially advantageous for hunting. The greater eye relief makes spatial orientation easier for them.
what you can’ t see
Our dogs actually see things that remain hidden from us. So they are able to see the magnetic field and the aura. Environmental disasters or thunderstorms can see them long before it is really there. This explains why some animals tremble in the morning when storms come in the evening. This phenomenon is explained by the magnetic sensor molecule. Researchers found the magnet-sensitive cryptochrome 1 in the retina of the eye, which reacts to the magnetic field. Some carnivores still possess this molecule, such as wolf, badger, fox, bear and some species of monkey, such as the orang-utan. (Scientific Reports 6, Articel 21848 2016). More about the 6th and 7th sense.
Summary
In summary, it can be said that compared to the human eye, colour vision, visual acuity and depth perception are reduced in dogs. Seeing in the dark or in poor lighting conditions, the perception of movement, the field of vision and the differentiation of grey tones are much more pronounced in our four-legged friends.