Your dog's senses allow him to behave and perform in ways nothing short of magical. Dogs perceive the world differently from the way we do – we share the same senses, but with remarkable differences.
The Nose Knows
The first thing your dog does when you walk in the door is sniff your legs. Dogs gather a lot of information from a quick sniff of their environment – both physical and emotional details. He smells where you've been and even how the experience affected you. Dogs sniff each other and each others' secretions constantly, monitoring various physiological and emotional changes on an ongoing basis.
Dogs live in a world of odors. Their sense of smell is their most refined sense; in fact, it is so refined a bloodhound can identify scales of skin shed by humans three days previously. They can also detect drugs in hidden in body cavities, can sniff out rats, termites, bombs, missing persons, bodies drowned or buried in snow or rubble, and even the presence of melanoma cancer. Their noses are about as sensitive as our eyes.
The scrolled, scent membrane inside a dog's nose is about four times greater in area than the equivalent smell organ in humans. In the dog's nose, there are over 200 million scent receptors in the nasal folds compared to our 5 million. Moisture on the nose helps to capture scent and transmit it onto odor-sensitive nasal membranes, which cover the nose's wafer-thin turbinate bones. These bones comprise of convoluted folds, ensuring that the tiniest amount of scent is captured within them.
See, Spot
Have you ever noticed how your dog acts when you are approaching him from a distance? He sees you immediately, and he stops and stares; but it's obvious that he doesn't know who is coming toward him. You start talking to him, perhaps calling his name, but he is still unsure, although he will act interested. Finally, when you get close enough to him that he picks up your scent, he will run to you happily.
Your dog trusts his sense of sight the least. However, while smell is his most refined sense, sight is his strongest. Dogs have no good biological reason to identify different colors. Though they can distinguish between certain colors, their color vision is limited and the colors may appear muted to them. Dogs see more clearly than humans do in dim light. This allows for increased movement definition of prey animals. Although their ability to see detail is limited, they are quite exquisitely sensitive to movement, and are able to pick up even very slight movement of hiding prey. A stationary object may not be noticed from a distance, but the dog will see it as soon as it makes a move.
Hear Ye, Hear Ye
You must have experienced the result of your dog's super hearing ability. You are sitting in your favorite chair reading or taking a nap, with your faithful pet lying at your feet. It's blissfully quiet – not a sound to be heard. Suddenly your dog leaps to his feet and begins barking loudly, his protective bark, and you run to the window to see who is approaching. But there's no one there. At least not at first. It takes moments before someone actually comes into view and walks by the house or into the yard.
The dog's ability to hear is incredibly acute compared to humans. They can hear sounds over a wider range of frequencies and a greater distance than we can. Also, experiments have shown that a dog can locate the source of a sound in about six-hundredths of a second. Their highly mobile ears capture sounds and funnel them down to the eardrum. You might see your dog cock one ear to capture the initial sound, and then use both ears to catch the maximum number of sound waves. Protection and guard dogs use their sense of hearing, along with their sense of smell, to detect possible intruders, sometimes from great distances.
Touch and Go
Touch is the first sense the dog develops and remains a powerfully important sense throughout his life. Mothers begin touching newborn
puppies almost immediately after birth by licking and nuzzling. Touch-sensitive hairs called vibrissae, which are capable of sensing airflow, develop above the eyes, on the muzzle, and below the jaws. The entire body, including the paws, is covered with touch-sensitive nerve endings. The physical sense of touch is very sensitive, although dogs do have a high threshold of pain.
Body sensitivity varies among dogs, but most enjoy being stroked around the head, chest and back. The most sensitive nerve endings are along the spine and towards the tail, and dogs show great enthusiasm in pats or extended rolls and slides on the grass.
The Taste Test
Dogs use their large tongues to lap up water, but they have few taste buds in comparison to humans, approximately one for every six, most of them clustered around the tip of the tongue. They can detect sweet, sour, bitter, and salty tastes. However, your dog has no real sense of taste as we know it; he smells rather than tastes. It's possible that dogs gain more information about food from their sense of smell than from taste. This may account for their desire to for indiscriminate chewing or eating.
How Do They Do That?
Then there all of the other things that dogs can do that seem to defy explanation – a kind of sixth sense. They seem to be able to detect changes in the earth's magnetic field; they may, to some extent, be able to detect infrared wavelengths of light, a kind of heat that living animals emit; they can detect sudden changes in barometric pressure when a thunder storm is brewing; they can detect vibrations from earthquakes much sooner that instruments; they can find their way home from long distances over unfamiliar terrain. They can even detect your mood.
Do dogs have a sixth sense? Maybe they do. Or maybe, like some believe, it can all be explained by already-known biological mechanisms. However you explain their abilities, dogs and their sensitivities are truly wondrous.
