Do Some Dogs Have Worse Night Vision Than Others?

Canine vision is suited to low-light situations. Perhaps you have noticed a dog's eyes glowing in the dark. That is because they possess an eye structure called a tapetum, which resembles a second reflector that redirects scant light back to the retina. Their retinas also have a dense concentration of rods --- the sensors that detect motion and black-and-white light. Furthermore, they have wider retinas that let in more light, and their lenses are closer to their retinas, shedding even more light on the situation. While some dogs have been bred for their keen vision, others have been bred for other desirable traits, leading to variation in the vision of dog breeds.

  1. Field of Vision

    • The placement of the eyes is a factor in canine vision. Dogs have a wider field of perception because their eyes are located on the sides of their head. They see about 240 degrees -- compared with humans, who see only a 180-degree field. Snub-nosed dog breeds, such as the pug, have a narrower field of vision, whereas long-nosed dogs, such as the cocker spaniel, perceive wider angles.

      According to Service Dog Central, breeds that are used as guide dogs for the blind have 75 degrees of binocular overlapping vision, compared with 120 degrees for humans and 30 to 60 degrees for most dogs. Also, a miniature dog, such as the Shih Tzu has less visual perspective from its low vantage point than a Great Dane.

    Perception of Color

    • Although dogs are not completely color-blind, they perceive only dual colors. They distinguish yellow and blue the best, making them akin to green-and-red color-blind humans. Their lack of color perception also results from the greater concentration of rods in their retinas, which leaves less room for color-perceiving cones. On the positive side, they are better than humans at telling the difference among shades of gray.

    Behavior and Breeding

    • Behavior can improve visual power. For example, the behavior of leaping in order to find an object it is looking for has enhanced the perspective of breeds, such as the English springer spaniel, according to veterinarian Paul Miller. Breeding also plays a role in visual acuity. German shepherds bred as seeing-eye dogs have a lesser tendency toward myopia than their wild-type cousins. Also, Labrador retrievers and other specially bred guide dogs have greater visual acuity than the average dog, which has only 20:80 vision.

    Motion and Depth Perception

    • Dogs are able to detect moving objects at hundreds of yards away because of their density of rod receptors. Also, they can perceive light flickering at about 75 Hz (e.g., a TV broadcast), which humans perceive as continuous images. Some breeds, such as German shepherds and Rottweilers, have a greater tendency toward myopia (nearsightedness). According to Malamute Health, wolflike dogs have more visual acuity, denser visual streaks in their fovea, and denser concentrations of ganglia --- twice that of most dog breeds.