Fun Facts About the Dog Sense of Smell

You know your dog likes to sniff. But why do dogs sniff so much? What do dogs smell, and how far can a dog smell? And why do they find all these scents so interesting?

Your dog’s snout isn’t just adorable—it’s also a well-oiled machine that provides them with loads of information about the world around them. Here are some fascinating dog nose facts…

How Does a Dog’s Nose Work?

Dogs have a much stronger and more refined sense of smell than their human companions—10,000 to 100,000 times stronger than humans’ sense of smell, depending on the dog breed.

Here are some interesting facts about your dog’s nose and how it works so well…

Dogs have between 100 million to 300 million olfactory receptors (smell receptors) in their nose, with scent-tracking breeds like Bloodhounds representing the higher end of that range. Compare this to just a measly 5-6 million scent receptors in humans.
In our canine companions, the part of the brain devoted to their sense of smell is proportionally about 40 times larger than ours! Even bigger than the section in our brain dedicated to sight.
Dogs’ noses are physically designed to optimize their ability to smell…
- During normal respiration, most inhaled air heads toward the lungs. But a small portion is “saved” for odor detection. This portion enters the nasal turbinates (a sponge-like mesh of bones covered with receptors for scent) at the back of the nose.
- When actively sniffing (making short sniffs for smelling rather than longer inhalations for breathing), air enters toward the center edges of the nostrils, then exits in a separate tract at the sides of the nostrils. This allows fresh air to be drawn in quickly and continuously without being pushed out by exhaled air, so a pup can pick up on even more scent signals. Essentially, a dog is breathing in and out at the same time!
Dogs have a special organ—the vomeronasal organ, or Jacobsen’s organ—located between their nasal cavity and the roof of their mouth that is dedicated to picking up chemical signals called pheromones from other animals. Pheromones can signal things like anxiety or readiness to mate, and thus they play an important role in social interactions.

Why Is the Dog Sense of Smell So Important?

In humans, vision is the primary sense for processing the world around us, assuming a person doesn’t suffer from visual impairment. In dogs, however, scent is their primary sense.

Based on the significant portion of their brain dedicated to smell, dogs arguably depend more on smell than humans depend on eyesight. Also, a dog’s left and right nostril move and process odors independently to determine which direction a scent is coming from.

Through their sniffer, canines learn a lot about their environment, including humans and other dogs.

Dogs use scent to identify their family (human, canine, or any other critters in the home), as well as friends and acquaintances. They also learn a lot about inhabitants of the neighborhood, or places they frequent such as walking paths or dog parks.

All of this makes sniffing very important to dogs. It allows them to better perceive the world around them, which probably lends a sense of security. A dog who can’t smell, especially in a new environment, may experience uncertainty or disorientation similar to a human who is placed in a new location wearing a blindfold.

So, it’s very important for dog owners to let their pup sniff when out on a walk, especially at spots that carry lots of scent signals, like a tree or post where other dogs have peed. Give your pup at least a few minutes to sniff around. And let them add their own “pee-mail” to the mix, i.e. contribute their own scent signal for other dogs to find.

Why Do Dogs Have Wet Noses?

One crucial purpose is to boost a dog’s sense of smell. Scent particles stick to a wet nose better than a dry one, allowing a pup to capture more information. A dog can lick their nose to transfer some of those particles to the Jacobsen’s organ, which helps to read chemical signals. The moisture on your pup’s schnoz comes from mucus glands in the nostrils and from your dog licking their nose.

Wet noses also help with temperature regulation. Dogs can’t sweat, but they lick their nose and allow the moisture to evaporate, which provides a bit of cooling.

While a wet nose is normal, a dryer-than-average nose can be normal for some pups. Also, an overly wet nose with abnormal discharge (especially mucus, blood, etc.) can be a sign of a problem. It’s best to know what’s normal for your dog, so you can notice any changes right away.

Why Do Dogs Sniff So Much?

Before modern civilization, a dog’s sense of smell probably played a large role in their survival. It helped them locate prey, avoid predators, find mates and companions, and come back to their home and their puppies.

Nowadays, domestic dogs may have a cushy lifestyle. But their nose has remained an important part of how they process the world around them.

Since dogs use their nose to explore and gather information, it’s only natural that they sniff a lot sometimes—especially when in a new place, or when meeting new people or animals. A pup may also sniff more than usual if they encounter an area full of scent signals (trees, posts, or other areas where dogs like to pee) or find a scent that’s interesting to them (even if it’s gross to us pet parents!).

Some of the things dogs might learn by sniffing include…

Who’s been there lately (human, other dog, or other animal), approximately how long ago they were there, and which direction they were traveling.
The person or dog’s gender, as well as information about their demeanor (friendly versus aggressive), mood (happy, anxious, etc.), and health status.
If it’s another dog, pheromones indicate whether that dog is available for mating.

How Do Dogs Benefit from Their Strong Sense of Smell?

As expected, dogs sniff a lot in new environments or highly trafficked areas. It helps them learn more, and it may facilitate social interactions with other dogs who smell familiar or friendly.

But sniffing around the home is also important. Familiar smells in the home environment lend a sense of comfort and familiarity. And a pup may give guests a good long sniff to determine if they recognize the person and whether that person is a threat or has pets of their own.

In addition to gaining information for safety and social interactions, dogs also just really enjoy sniffing! Sometimes, they encounter a totally new smell, or an odor that they find especially interesting. Exploring these scents can bring fun and mental enrichment.

Additionally, sniffing is a natural behavior for canines. Allowing a dog to perform instinctual behaviors is good for their mental and emotional wellbeing.

How Can Humans Benefit from a Dog’s Sense of Smell?

Dogs’ amazing sense of smell has certainly benefited their human companions. Since dogs are intelligent, many breeds with strong scent capabilities can be trained to assist humanity with tasks related to safety and health.

One example is search and rescue dogs, who can be trained to sniff out humans in need of rescue during situations like natural disasters. They can also aid in finding missing persons or tracking down wanted criminals.

Drug-sniffing dogs aid security authorities in uncovering drugs and other contraband. And some pups can sniff out explosives.

Perhaps most amazing of all is a dog’s ability to accurately detect certain markers for disease, including some types of cancer. Trained service dogs have been able to help humans with a variety of medical conditions. For example, they might alert a diabetic person if their blood sugar is dropping dangerously low, or run to the side of a child who’s about to have a seizure.

While the exact mechanism by which dogs are able to do this isn’t entirely understood, there’s a good chance their finely tuned sense of smell has something to do with it. Their nose may be able to detect shifting hormone levels or other scent cues that humans can’t pick up on. Researchers are even trying to hone this ability to detect certain types of cancer.

As if this weren’t enough, dogs can also help with wildlife research and conservation. Specially trained wildlife tracking dogs can help researchers locate specific species of wild animals, including orcas!

What Can Affect a Dog’s Sense of Smell?

While it would be unusual for a dog to lose their sense of smell entirely, there are many health conditions that can diminish a dog’s smelling ability.

Like humans, a stuffy nose can block nasal passages and cover scent receptors. This could happen with certain bacterial or fungal diseases, or foreign objects stuck in the nose, for example.

Cancer of the nose is another possibility in older dogs, which may be accompanied by nosebleeds, swellings in the nose or snout, or other symptoms. Even very bad dental disease could affect the nasal passages.

Health conditions affecting the nose can be uncomfortable, make it more difficult to smell food, and even impact breathing if severe. Plus, for all the reasons discussed above, loss of smell can make a pup feel less secure.

Nurturing Your Pup’s Sense of Smell

It can be a lot of fun to watch our pets explore the world and experience new things. For dogs, sniffing is an essential part of that exploration.

So, even if a walk is taking too long and making you late for work—or even if your dog embarrasses you by sniffing your friends in inappropriate places—try to understand where your pup is coming from. See if you can leave on your walk a few minutes earlier to allow your pup some good sniffing time as part of their mental and emotional enrichment. Encourage them to sniff your friends’ hands instead of scolding your dog.

Consider enriching your dog’s life with new scents, such as taking them on a drive where there are farms nearby or going for walks in new places. For anxious pups, try dog pheromone products, which send soothing scent signals.

If you have any questions or concerns about your pup’s sniffer or their health in general, set up a telehealth appointment today with one of our caring veterinarians.