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A dog’s sense of smell


We all know the image of a dog walking quickly, nose pressed to the ground, head sweeping back and forth. We’ve seen the complete confidence of a dog who knows when they’ve got it, shooting off in the right direction. And we’ve all heard stories, in movies and in real life, of canine heroes finding lost humans. A dog’s sense of smell is truly astounding. But what is it that makes it so impressive? How does it work?

Advanced noses

The key is in the nose. To put it plainly, a dog’s sense of smell is roughly 10,000 times stronger than that of a human, and far more complex. They’ll identify each other, as well as their humans, through their scent. Take the typical butt-sniffing between dogs, for instance. It’s the way they say hello, the way they decide if this new dog is a friend, what they’ve been doing, and maybe how old they are. In other words, a much more straightforward interaction and relationship than you’d find between humans. Though, it might be a little awkward if we all started sniffing each other’s rears.

When scientists say that a dog’s sense of smell is 10,000 times better than ours, what they’re talking about is olfactory receptors. Where humans only have around 5 million of them, dogs have between 150 and 300 million, depending on the breed. It’s no wonder they pick up on smells we can’t even imagine.

Using the dog’s sense of smell

There are many ways to take advantage of a dog’s sense of smell, both big and small. Some use it for hunting, tracking down deer and other game in the middle of a scent-crowded forest. Others only use it for fun and competitions, where the best tracker wins a prize and is showered with treats and cuddles.

Then there are dogs with jobs. These jobs can range from sniffing out drugs to finding people buried beneath collapsed buildings, and the dogs who do it take it very seriously. A dog’s sense of smell has been known to discover cancer (even in spots on the body declared cancer-free). They can find humans stuck alone in the mountains, staying with them until help arrives. Dogs are used every day for life-saving tasks and police work, bravely working side by side with their humans. Frankly, we wouldn’t manage without them.

The best-nosed breeds

Certain breeds are made for scent tracking. The most well-known, perhaps, is the bloodhound, and this is for good reason. Aside from the incredible number of olfactory receptors (a whopping 300 million), even their big, flappy ears help. With the nose pressed to the ground, those ears help fan up even more smells and odors, giving the dog even more to work with. The wrinkly skin around and under the dog’s face also helps trap the scents, so that the dog will easily be able to focus on their work. They can also follow a scent in the air, as well as on the ground. In other words, once a bloodhound catches a scent, nothing will get in their way of finding the source of it. This is why they’re considered the best of the best in this particular field.

A close second to the bloodhound in terms of tracking ability is the basset hound. The ears and loose skin serve the same scent-wafting and scent-trapping purpose, but the dog’s body is closer to the ground. Like the bloodhound, this dog is simply born and bred to track.

The beagle is also an excellent sniffer, with the same number of olfactory receptors as a German Shepherd (around 225 million of them). This dog is often used in airports to sniff out contraband, and is also popular with hunters.

The German Shepherd is a versatile dog as it is, even aside from their super-nose. This breed tends to sniff the air rather than stick to the ground, however. Since they’re so hard-working and trainable, the German Shepherd often finds use for its skills in law enforcement, military, and search and rescue. Other breeds worth mentioning as great sniffers are the Labrador retriever, the Belgian Malinois, the Coonhound, and different pointer breeds.

The science of it all

There’s a lot to keep track of when it comes to explaining why a dog’s sense of smell is so impressive. Most of it has to do with the number of olfactory receptors, as mentioned before, but there’s also the shape of the nose and nostrils. The shape is different from that of human noses, allowing the exhaled air to basically swirl around and waft more scents back toward the nose. A dog’s nose is wet and textured, which allows scents to easily be caught up and brought into the nose for analysis. Another fun thing about dog noses is that each nose has a pattern as unique as a human fingerprint.

There is also the fact that when humans breathe, the scents go along with the air through the same passage. With dogs, there are two separate passages; one for the air, and one for the scents. In other words, no distractions for the brain when it tries to make sense of all the smells rushing in. Ever noticed how a dog huffs through their nose at something they’re particularly interested in sniffing? The huffed air fans up new scents, giving them even more to work with. Dogs, in short, are highly adapted to existing in a world of smells.


A dog’s sense of smell is just one of the many things they use to help out their humans, day to day. With it, they help us hunt, find things, find people, track down cancer and drugs, and even forged money. And just like with any other breed with a certain specialty, those with better noses have been bred to enhance that particular trait.

Another kind of job for dogs is assistance. They help guide the blind, help the physically disabled, and those with physical issues such as epilepsy. But they also offer much-needed emotional support to those with mental health problems, like PTSD, anxiety, and depression. Dogs are inherently helpful and emotionally attuned animals, which is why they make such excellent companions, but that’s not the only reason. A dog’s sense of smell also matters, even here. For example, a stressed individual will have spikes in certain hormones, which a dog can detect ― sometimes even before the person themself does. Simply put, we smell different depending on our mood. Other humans can be fooled through body language, smiles, and words, but a dog won’t be. No matter what you present outwardly, your dog will know whether you are calm, stressed, happy, angry, or upset. And when they know, they will react and behave accordingly, soothing their human if they need it.

Dogs use their noses to help in many ways, including emotional support

When it comes to dogs, there are plenty of reasons we work so well together. There are plenty of reasons they seem to simply know what we’re feeling. And while a dog’s sense of smell is only one of those things, it may be one of the most valuable and easily forgotten ones.