Taking your dog to the park or for a hike can be a symphony for your eyes, especially in times of change like spring or fall. From the red bricks lining the sidewalks to the reflective yellow street signs, humans are constantly bombarded by a technicolor onslaught. Turns out, however, that your canine is seeing something completely different. Your dog has only a small percentage of your total vision, which makes their perception of color much more narrow than yours. So what causes this lack of ocular sensitivity? What kind of experience is your dog having during what humans perceive as “beautiful” moments, like a sunrise?
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The Root of the Behavior
The eye’s retina contains a plethora of nerve cells, and these can be split into two categories. Ocular rods detect light and movement, while ocular cones perceive color. Your dog’s eyes contain between 1/9th and 1/12th of these ocular cones. These color sensing cones reside in the rear of the eye. Because humans have so many more of these cones, they see what they consider to be a “full” color spectrum. Dogs, however, can only see 3 colors: blue, blue-violet, and yellow. For them, any other color appears as gray and featureless. While dogs have much fewer cones than we do, they contain almost triple the amount of rods, This stems from their ancient beginnings as hunters. Being able to see in low light while having a keen eye for motion allowed them to hunt small prey during the evening.
This divergence in how dogs see color can actually be compared to red-green color blindness in humans. Human color blindness stems from specific genetic defects, as opposed to a born trait. The person is usually lacking the gene that tells their eyes to grow the prerequisite amount of cones. Color blindness and its effects are different from the naturally occurring condition in dogs, but the results tend to be the same. The ideas behind the diminishment of color in canine sight have been carefully studied over the years, most notably by a Dr. Neitz, a professor at the University of California in Santa Barbara. His most popular test involved showing dogs panels of differently colored lights. The dogs would be shown two colored lights that matched, and a third of a seperate color. The dogs needed to select the differently colored panel to receive a treat and move onto the next test. His testing confirmed what up until then had only been suspected, that dogs see in primarily 3 total hues.
Encouraging the Behavior
From an evolutionary standpoint, the accepted scientific explanation is that bright colors are important to notice only for herbivores and omnivores. As dogs were and still are primarily carnivores, spotting bright fruits and vegetables wasn’t a habit that they continued to develop over time. Instead, their light sensitivity improved in order to see prey from greater distances. It is entirely possible that some distant, early ancestors of modern dogs was able to see in the same degree of color that we as humans do, but unfortunately humans will never truly know.
An important point to consider here is that your dog doesn’t rely on his vision nearly as much as he relies on his other senses. Smell in particular is the most important tool in your dog’s kit. It is your dog’s main way of understanding the world around him. Their nose is actually kind of an opposite example of their eyes, in that they can smell in a much broader spectrum than humans can. This enables them to sense individuals coming from far away, know where things have been buried, and find spots that have been marked by either themselves or other animals. This is yet another trait that comes directly from your dog’s DNA.
Other Solutions and Considerations
Many vets caution against certain types of light or color displays, as they can cause seizures in some dog breeds. In fact, dogs are sometimes more susceptible to epileptic episodes than human beings are! Fireworks displays, in particular, are a negative place for your canine to be. Not only can the lights cause unwanted neurological effects, but the loud explosions can occasionally permanently damage your dog’s hearing.
Occasionally, dog sight can be so severely affected by the lack of cone growth that they can suffer from sun blindness. This is a condition in which your dog is overwhelmed by the lack of color definition and stops feeling comfortable moving around. Luckily, in the past few years, veterinary science has produced “doggy shades” that mount comfortably to your dog’s head. At this point, these dog glasses are the only solution available for this particular affliction.
So, turns out dogs see some colors, but not all of them. And strangely, their sight operates a lot like a human’s does, just in a more limited way. While this isn’t normally an issue, special attention should be paid if it seems like your canine is uncomfortable in direct sunlight. With the right accessories, maybe he’ll finally be able to see the light!