Why Do Dogs Sniff? Exploring a Canine's Sense of Smell

Published July 13, 2021
Dog sniffing other dogs bum

Why do dogs sniff everything? You may have wondered why dogs sniff each other's butts upon meeting, or why your canine companion sniffs around before deciding on the perfect spot to poop. Humans make sense of the world with their vision. Dogs, on the other hand, make sense of the world with their nose.

A Dog's Nose Compared to A Human's Nose

What is it about a dog's sense of smell that makes it so effective? To begin, their noses are far more sensitive than a human's nose is. Humans have only 5-6 million scent receptors. Dogs' nostrils have up to 100 million or more scent receptors, depending on the breed.

Bloodhounds, the amazing breed of dogs known to track nearly anything, have 300 million scent receptors! Compared to the number of scent receptors humans have, that's quite remarkable.

Dogs Sniff to Gather Information

Just as humans rely heavily on eyesight to comprehend their world, dogs rely heavily on their noses to gain insight. The way something smells conveys more information to dogs than its appearance, feel, sound, or taste. Consider how dogs greet one another. Rather than barking or shaking their paws, information is communicated through their noses. Indeed, dogs derive far more complex information from scent than people can fathom. Human noses and brains are simply not wired in this manner.

Dogs Have a Special Organ with Scent Receptors

Between the roof of the mouth and the bottom of the nasal tube, dogs have a particular scent organ called the vomeronasal organ. Also known as the Jacobson's organ, it is found in various animals such as snakes, cats, and horses. It is equipped with particular receptors for sensing pheromones. Humans possess the organ as well, although it is doubtful that humans communicate via pheromones in the same way that dogs do.

Why Dogs Sniff Butts

Many pet owners are baffled as to why dogs smell butts. What's the deal with sniffing another dog's butt? Why don't they sniff their ears or their feet? The answer has to do with anatomy, anal glands in particular.

Two little sacs called anal glands are located inside the rectum and they emit a foul-smelling material through a pair of tiny holes. When the rectal sphincter muscles engage during a bowel movement, the glands are naturally released. The stench of the anal glands is covered by the odor of the dog's stool, so pet owners are unaware of the situation; however, dogs can smell the difference.

Dogs have an edge over humans in that they use their acute sense of smell, in combination with a visual assessment, to convey crucial information about a new furry friend. Their keen olfactory capabilities allow them to communicate chemically using biological chemicals generated by other dogs.

The chemical aromas can tell a dog's gender, mood, and even what he likes to eat. A dog can ascertain whether a new companion is male or female, happy or hostile, healthy or ill, simply by smelling them. A brief sniff gives dogs a rough notion of each other, allowing them to better know one another and ensuring their new furry friend is not a danger. Or, if he is a danger, this signals to the dog to get away from the situation as quickly as possible.

Why Do Dogs Sniff Before They Poop?

Since your dog sniffs to gather information, that's precisely what he may be doing before he decides where to poop. He's checking to see what other dogs were previously in the area, where is safe and where may not be, or if any other dogs have pooped in that spot before. The scent that is released from their anal gland will leave their information behind, so they want to make sure they are pooping in the right spot.

Some dogs may also simply be taking longer to spend more time outside. If your dog doesn't get a lot of outdoor time, he may use his potty breaks as a breath of fresh air and time to enjoy his surroundings. If you're trying to get your dog to go potty faster, you can try spending more time outside providing leisure time. Then, potty breaks would be just that, the time to go potty.

Dogs Sniff to Establish Dominance

The way dogs sniff one another's rear ends can reveal who is the dominant dog and lay the groundwork for a potential bond. While the dominant dog begins sniffing, the submissive dog waits his turn. A submissive dog may be the first to stop smelling and retreat. To end the smelling session, a dominant dog may growl or show some other form of 'alpha' behavior.

Some dogs prefer to keep their knowledge to themselves, and they may sit and clench their tails over their rectums to reduce the amount of aroma they generate.

Dogs Can Smell Disease

Dogs are renowned for their ability to detect cancer. They can be trained to detect a range of different types of cancer, including skin cancer, breast cancer, and bladder cancer, using samples from known cancer patients and healthy individuals. Their level of accuracy is higher than most tests, coming in at 97% accurate. Additionally, it was recently discovered that dogs have the ability to smell COVID-19.

For people suffering from a chronic disease, such as narcolepsy or epilepsy, a dog's unique scent receptors, paired with their dedication to humans, is why they are used as service dogs worldwide. Dogs can detect biochemical changes in the body that precede an attack, and assist with various activities to prevent injury. But most significantly, dogs may alert their handler up to five minutes before an attack occurs, allowing them time to retreat to a safe location or position.

Dogs Have Scent Memory

Dogs have a strong scent recall. They can recognize other dogs they haven't seen in years, and they remember who the dominant half of the pair was, just by smelling them. When dogs from the same family are separated for an extended period, they use their sense of scent to reconnect. Changes in scents could reveal where the dog has been, what he has eaten, and what he has done.

This is also why, when people see videos of a dog reconnecting with his owner even years later, the owner is often immediately recognized. Their scent gives them away.

Dog Sniffing Is a Normal Behavior

If your dog's sniffing activities make you uncomfortable, attempt to divert their attention. When visitors arrive, keep your dog on a leash to keep them under control. Teach them to greet people by sniffing their hands, and praise them for being calm. While you may be embarrassed by your dog sniffing other dogs' butts, this is very normal dog behavior.

Why Do Dogs Sniff? Exploring a Canine's Sense of Smell