Many people make the mistake of assuming that their dog sees the world the same way they do. We all know of a dog’s great sense of smell, and many of us have heard that dogs are colourblind, but few of us really know what this means, or how a dog’s vision may be different from ours.
First of all, dogs are not completely colourblind. Vision in both humans and canines is measured by photoreceptors known as cones and rods at the back of our eyes. Cones are able to pick up fine details in colour, whereas rods are able to better pick up motion and dim light. The ratio of cones to rods in our eyes determines whether we are better at picking up fine details and colours, or better at picking up motion and seeing in the dark. Dogs have significantly more rods than humans, and as a result, they are much better at seeing in low-light situations, but less cones means they are less able to perceive colour. Dogs are still able to see some colour, but cannot distinguish between greens, yellows, oranges and reds. To those of us with guide dogs, this information may be troubling, as one starts to wonder how a guide dog can differentiate between a green light and a red light at an intersection. However, there are a number of other queues that a dog will pick up on, including brightness and position of the light, as well as noise and traffic.
Secondly, the lack of cones in a dog’s eyes affect the level of detail with which they can see. As a result, they are less able to visually distinguish objects that are far away. While humans with ideal eye-sight are said to have 20/20 vision, a dog may only have 20/75 vision. This means that a dog has to be 20 feet away from an object in order to see it with the same level of detail that a human can see 75 feet away. Many working dogs, such as German Shepherds, Belgian Malinois or Dutch Shepherds, have been bred for better senses, including vision. Your protection dog may have better vision than a house pet, but it would still be less than that of a human. Of course, vision is not the only sense at a dog’s disposal. While your dog may not be able to see you sitting still at the other side of a field, he may be able to hear you, and can almost certainly smell you. On top of this, any amount of movement will be picked up by your dog’s rod-heavy photoreceptors.
Keeping these factors in mind is important in effectively training and working with protection dogs, guard dogs and security dogs. You have to know your dogs strengths and weaknesses, and how to employ your dog at its absolute best.