A Dog's Sensory World
Dogs see better in the dark than we do. Remember that the next time you’re chasing your dog around the yard at night.
A Dog’s Sensory World
Dogs are reputed to have highly refined senses, far superior to our senses in many ways. There are some areas, however, where our senses have dogs beat. Here’s a run-down of four of a dog’s most acute senses and how they compare to ours.
A Dogs’ Eye View
So just what does a dog see?
- Dogs can’t see the fine details that we can (it’s a good thing they’re seldom asked to read the fine print). This is because they have fewer cones – the light sensitive receptors responsible for day vision, detail vision, and color vision.
- Dogs can’t see the rainbow of colors we can, but contrary to popular belief, they aren’t colorblind. Their cones lack one of the three receptor chemicals that allow us to mix color wavelengths. We have receptors for blue, green, and red, but dogs only have receptors for blue and red. This means that their color vision is similar to that of red-green colorblind humans. At least they don’t have to match their socks
- Dogs see better in the dark than we do. Remember that the next time you’re chasing your dog around the yard at night. Their lack of cones is made up by extra rods – receptors that are more sensitive to dim lights. Their eyes also have a rounder cornea and lens and a layer of cells behind the retina that reflects light back to the receptors for a second chance to be absorbed, all of which help magnify light and improve night vision. That layer, called the tapetum, is what causes your dog’s eyes to shine at night when you aim a flashlight at them.
Most blind dogs get along very well by relying on their other senses. Owners can help blind dogs by placing sound and scent beacons around the house and yard and by making textured pathways inside and out. Blind dogs still must be walked on a lead when out of the yard and special precautions must be taken so that don’t find themselves alone in strange places. Over all, blind, deaf and even anosmic (“smell-blind”) dogs live full and happy lives because they make up for one sense with another – and their other senses are quite acute.
A Nose for Trouble
Though dogs make good use of their vision, their other senses are so acute that they can partially compensate for visual loss. Their sense of smell is legendary. Their tested ability to smell a particular component of human skin is one hundred million times better than that of humans. Dogs trail people and other animals by scenting microscopic rafts of skin that fall to the ground, as well as the scent of their clothes, make up, exhaled air, and even food that they ate. Dogs can also detect the crushed vegetation and stirred-up dirt left by footsteps.
Hi-Fido Hearing
Dogs can also hear things we can’t. The lowest sounds that dogs and people can hear are about the same, measuring around 45 to 65 Hertz (Hz) – about the same pitch as the lowest pedal notes of a pipe organ. But people hear sounds of around 3000 Hz most easily (most people's voices are pitched at that frequency) and dogs are most sensitive to higher pitched sounds, around 8000 Hz.
The highest pitch that people can hear is 23,000 Hz, whereas dogs can hear up to 45,000 Hz. Ideally, so-called “silent” dog whistles emit a frequency between 23,000 and 54,000 Hz, although some emit frequencies as low as 16,000 Hz (which people can hear) or much higher than 55,000 Hz (which dogs can’t even hear).
He Ate What?
You may have seen your dog eating cat poop and then wonder why she’s sticking her nose up at the dog food you offer. Surely there’s something wrong with your dog’s sense of taste! Well, maybe not wrong, but definitely different.
Dogs lack the strong, salt-specific taste buds we have. Though dogs enjoy sweets, they don’t like saccharin, probably because their taste buds respond more to the bitter aftertaste than they do to any sweet aspect. Basically, when they eat the same foods as we do, the taste is much different to dogs. So the next time your dog is rifling in the litter box looking for treats, consider that they might be tastier than you think!
Caroline Coile, PhD, is the award-winning author of 26 books about dogs. Her own dogs have been top ranked in show, obedience, agility and coursing competitions, but she most enjoys the time she shares with them at home.