When my little dog, Daisy, was younger, we went for miles-long walks. But after she turned 10, she stopped wanting to go the distance. She only wanted to give everything she encountered a nice, long sniff.
It now takes us about 22 minutes to walk to the end of our block and back. I figure it's her outside time, so we might as well spend it the way she wants. I listen to music with earbuds and marvel at how she'll spend the length of an entire song sniffing a decorative rock.
It turns out Daisy's sniff time is as valuable as a regular walk. In recent years, scientists have learned that sniffing provides dogs with significant mental stimulation that can be as exhausting and beneficial as a long walk.
Why Do Dogs Sniff Everything?
When my little Daisy slowly sniffs her way down the block, she is collecting olfactory information that researchers have found gives dogs a "three-dimensional image of the surrounding world across time."
Sniffing gives dogs an understanding of the past and present. They can decipher who else has come through the area, including known doggie associates or even potential predators.
As a dog inhales, air moves through two distinct pathways. About 12 percent of the air goes through the upper flow path, where odor molecules travel to the olfactory region. The rest of the air goes through the lower pathway to the lungs. Whereas the lower pathway exhales air, the upper pathway hangs onto the odor molecules and doesn't exhale them.
A Nose for Details
Dogs' nostrils are also distinct. The right nostril initially does all the work when a dog happens upon a scent. If the scent is unfamiliar or seemingly dangerous — perhaps indicating that a predator passed through — then the right nostril keeps sniffing. The left nostril only takes over if the scent is familiar or seemingly safe, like a food's aroma.
Losing the Scent
As dogs age, they may lose some of their olfactory tissues and cells, and they might not be as sensitive sniffers as when they were younger. However, older dogs may build up a memory bank of smells, which means they can make sense of more complex odor information.
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How Much Stronger Is a Dog's Sense of Smell?
A dog's nose is so sensitive that they would be able to determine if a teaspoon of sugar was dropped into a body of water the size of two Olympic-length pools. This is because dog noses have far more sensory receptor sites than humans.
The typical human has about 6 million sensory receptor sites. In contrast, most dogs have 220 million sensory receptor sites. Depending on the breed, dogs like beagles and bloodhounds can have as many as 300 million sensory receptor sites.
Dogs' sense of smell is millions of times more powerful than humans. They can smell when and how an object was touched. They can smell decay, pheromones, and even disease. Scent is considered a dog's most important sense, and the information they receive from sniffing shapes how they view the world.
Should I Let My Dog Sniff on Walks?
The American Kennel Club recommends taking your dog on designated sniff walks in which the dog gets to move slowly and sniff everything of interest (also called scent walk or a sniffari). Sniff walks provide mental stimulation that helps a dog avoid boredom. And because of the mental stimulation, a sniffari can be just as exhausting as a longer distance walk.
With a sniff walk, the dog gets to spend as long as they want sniffing a hydrant or fence post. The human on the other side of the leash isn't trying to get their steps in, nor are they telling their dog it's time to move on.
Sniff walks might not mean traveling far during their typical walking time. Whereas a regular walk might cover a mile in 20 minutes, a sniff walk could mean a block or two in the same time frame.
Stop and Sniff
Even when they're not on a designated sniff walk, animal behaviorists encourage pet parents to give their dogs time to sniff because it is their most relied-upon sense. Whereas humans can typically see as far as 75 feet, dogs can only see about 20 feet away. And although their hearing range is broader than ours — we stop around 20,000 hertz, and they can go up to 45,000 hertz — their sense of smell is the most important.
Not permitting a dog to stop and sniff on a walk means important and interesting smells are whizzing past a dog as they are pulled along on the leash. One animal behaviorist said that pulling a dog away while they are sniffing would be similar to driving past a world heritage site and forcing everyone in the car to look down at their own knees instead of Stonehenge or an Egyptian pyramid.
Frequently Asked Questions About How a Dog Sniffs
How Far Can a Dog Smell?
Dogs have an incredibly keen sense of smell. They can detect odors at distances up to 12 miles away. Some breeds with more developed olfactory capabilities, such as Bloodhounds, can follow a scent trail for 11 miles.
Can Dogs Smell Fear?
Yes, dogs can smell fear. They are highly sensitive to human emotions and can pick up on subtle changes in body odor when a person is afraid. While they may not understand fear as humans do, they can detect the chemical changes in our body caused by fear, such as increased sweat and adrenaline.
Why Do Dogs Sniff Butts?
Dogs sniff butts as a form of greeting and to gather information. The anal glands of dogs secrete unique scents that convey a wealth of information about the dog, such as its diet, gender, emotional state, and more. This behavior is a key part of canine communication.
Why Do Dogs Sniff Before They Poop?
Dogs sniff before they poop to find the perfect spot. This behavior is driven by their instinct to mask their scent from predators. By choosing a spot with existing scents, they can blend their smell into the environment, making it less noticeable.
What Does It Mean When a Dog Sniffs You?
Dogs can learn a lot about humans through their unique scents, including their mood, health, and if they've been around other animals. When a dog sniffs a person, it's gathering information. It's also a sign of curiosity and a way to become familiar with someone new.
Why Do Dogs Sniff Each Other?
Dogs sniff each other as a way of communication. It's similar to a handshake in humans. By sniffing, they learn about each other's diet, gender, mood, and health. This is an essential part of their social interaction and helps them understand their social hierarchy.
Why Do Dogs Sniff the Ground?
Dogs sniff the ground to gather information about their environment. The ground is full of scents from other animals, food, and various objects, providing a rich tapestry of information. This behavior is instinctual and helps dogs understand their surroundings, track prey, or find mates.
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