Dogs do not see in front of them for the simple fact that they really don't have a great need for this feature. Mother Nature always knew best what to do when it comes to equipping living beings with body parts.
Some animals may simply need some body parts more than others (think giraffes needing those long necks to eat from trees!), and therefore, some body parts and functionalities are more accentuated than in other species. Comparing the eyes of dogs with the eyes of humans (this is called comparative anatomy by the way) can come handy in better understanding their function.
Dog Eyes Versus Human Eyes
Dog eyes may share several structural similarities with the eyes of humans, however, there are also many differences. Sure dog eyes and human eyes share the fact that they have pupils, irises, eyelids and eyelashes, but dogs and humans have several different structures or different quantities of structures or lack thereof. Here is a rundown of differences between dog eyes and human eyes. .
Dogs have a third eyelid. Also known as nictitating membrane, palpebra tertia or haw, a dog's third eyelid is a special membrane drawn across the dogs' eyes to protect the eyeball and keep it moist while the dog is sleeping. It's often what causes dog owners to think that dogs sleep with their eyes open.
On top of providing protection, a dog's third eyelid is responsible for producing about 40 to 50 percent of the dog's tears. In humans, the third eyelid has shrunk to a rudimentary bump in the inner corner of the eye.
Dogs have a tapetum lucidum. It is thanks to this mirror-like layer located behind the retina that dogs see better in the dark. This reflective surface doubles the sensitivity of a dogs' eyes in low light. Humans lack a tapetum lucidum.
Dogs have a higher density of rods than cones. Rods are sensitive to dim light and help dog eyes detect and follow movements. Cones, on the other hand, help see colors well, but they fail to allow to see in low light conditions. Human retinas have more cones compared to dogs which allows the better color vision experienced by humans. Dogs instead see colors less vibrantly. Intrigued? Discover how dogs see colors.
As seen, dogs are equipped with different eye structures compared to humans. These structures were adapted to enhance a dog's survival.
An Eye for Distance
If we look at a dog's evolutionary past, we will see that a dog's ancestors highly depended on meals that would run away and camouflage. Many of these critters would come out at dusk and dawn.
It was therefore of primary importance that canids, as successful hunters, had eyes that could see well in dim light and that could detect movements that caused prey to stick out and prevent them from successfully camouflaging.
Humans on the other hand, depended more on seeing bright colors and details. This is likely because a human's evolution depended to a good extent on distinguishing ripe fruits. Humans also weren't fast as other animals so they relied on their brains and vision to build weapons to hunt down prey. On top of this, humans are also equipped with opposable thumbs which dogs lack.
Without opposable thumbs, dogs didn't need to closely examine things at arm's length, explains veterinarian Dr. Christopher J. Murphy in the book "The Secret Lives of Dogs." Rather, dogs had to focus more on prey at a distance so to successfully run them down.
It would have been unusual for a dog to have prey right a paw's length away, unless it was perhaps dead or dying, in which case, dogs would have used their powerful sense of smell. For prey that was so up close, those powerful noses would have therefore readily led dogs straight to their prize.
A Blind Spot Under Their Nose
On top of lacking opposable thumbs and eyes meant for seeing in the distance, dogs have a cumbersome nose. Unlike ours which is discreetly placed in the middle of our faces, dogs have rather prominent sniffers.
There are, of course, some exceptions to the rule such as pugs (or other brachycephalic dogs with smushed-in noses).
Once again, evolution programmed dogs to be this way. Dog noses are equipped with turbinates which are intricate mazes made of bone. Turbinates control how air moves through the dog's nose providing an increased surface area.
This helped amplify a dog's reception of smell. Long noses helped accommodate these turbinates. However, they came with a price: a blind spot down the middle of the dog's face.
On top of this, dog faces were purposely crafted so that they could see what was happening to the sides and far in front of them. Their eyes were strategically set apart allowing greater peripheral vision than humans. A dog's peripheral vision is estimated to be around 240 to 250 degrees, while in humans it's closer to 180 degrees.
Dogs are also very nearsighted compared to humans, putting their vision at around 20/75, whereas, in humans perfect vision is 20/20. Dogs have a hard time seeing stationary objects clearly, while humans can see objects clearly close up.
This explains why your dog may fail to see a toy that is right in front of his nose. However, move the toy slightly to the side and your dog will readily spot it.
Did you know? Some dog breeds have better vision than others. A sighthound's vision is known for being superior. Sighthounds are known for having a peripheral vision approaching 270 degrees and a "visual streak," which is a horizontally aligned area in the retina lined up with ganglion cells. This helped them spot prey over the wide-open lands in the desert.
Labradors and golden retrievers are known to have decent eyesight too because sharp vision was needed in order to locate downed birds from a distance. On the other hand, German shepherds and Rottweilers are known for being rather short-sighted.
Now That You Know...
As seen, dogs have good reasons for not seeing things right in front of them. While dogs can't see colors as humans and may fail to see things right in front of them or detect the most minute details, the trade-off is that they excel in seeing in dim light and are fast to identify movement especially at a distance.
Now that you know how your dog sees, consider these tips to help him out:
- Choose toys of colors that are readily visible to dogs such as yellow or blue.
- Purchase bigger toys that are easier to detect.
- Use toys that squeak for easy detection.
- Don't shave your dog's facial hair. Dogs have whiskers under their chins that help them locate objects right under their faces.
- Consider that as dogs age, their vision may decline and they may have a harder time seeing. Not to mention, they are predisposed to eye issues such as cataracts and glaucoma.
- See your vet at once if you notice vision loss in your best friend.