How Good Is a Dog's Sense of Smell? And What About Cats?

You’ve probably heard that dogs have a strong sense of smell. Compared to what we humans can smell, that’s an understatement. To put it mildly, canine noses are an absolute marvel!

It is amazing just how sensitive, powerful, and important a dog’s entire olfactory system is to its survival and overall wellbeing. To drive that point home, here are 10 interesting facts you probably didn’t know about a dog’s nose…(with 5 more fun feline facts below them):

Dog noses have 300 million receptors. This sounds even more impressive when you realize that humans only have 6 million! These receptors make dog noses so powerful they can detect substances at concentrations of one part per trillion…for instance, a single drop of blood in 20 Olympic sized pools!
The “scent analyzing” part of a dog’s brain is bigger than ours. Way bigger…in fact, 40 times larger than a human’s!
Dogs are neophiliacs. This means they love and thrive on new smells and odors. This is why they often lose their minds with excitement when sniffing a dog or person they’ve never met before. It’s their way of getting to know everything about them. This is also why regular walks outside are so important for the mental and emotional health of your pup. All the sights and smells keep their brain active, stimulated, and continually learning.
Dogs breathe in and out simultaneously. If you’ve ever had a dog get close to your ear as he’s sniffing you, it actually sounds like he’s inhaling and exhaling at the same time—because he is! When dogs exhale, the air exits through those slits you see on the sides of each nostril. The air swirls out in such a way that new air and smells can be ushered in at the same time.
Breathing and smelling are separate actions. There is a fold of tissue inside each nostril to help separate the act of smelling and the act of breathing.
Dogs can read (or rather, smell) your emotions. You may be able to hide your feelings from other people, but not from your pup! They can smell fear, sadness, anxiety, happiness, and more. Similarly…
You can’t outsmart a dog. Think you can hide a bone or your pup’s favorite toy? Nope! They can smell it from a mile away (literally)! Think you can sneak up on him? Negative! Every human has a unique scent, and dogs identify people via their trademark smell rather than their appearance. Furthermore, they can detect your presence before you are anywhere near them.
A dog’s nostrils work independently of each other. Not only can dogs wiggle their nostrils independently (humans can’t), they smell separately with each nostril. Dogs know which nostril picks up specific odors. Their brains use the information picked up from each nostril to help them identify the locations of certain things. This is why…
Dog noses can be used for human benefit. With training, dogs can learn to use their unique nasal abilities to locate bombs, firearms, drugs, bodies, and even sniff out diseases.
Some breeds have stronger senses of smell than others. Hound dogs boast the strongest noses, while dogs in the working group (Shepherds, Retrievers, etc.) come in a close second. Flat-nosed (brachychephalic) dogs have much shorter noses, which somewhat affects their sniffing abilities. They’re still better than you though!

What About Cats?

While most (though not all) dogs take the cake in terms of “nasal power,” cats have nothing to be embarrassed about in this department.

Just as dogs use their noses to identify people/objects and “see” the world, so do cats. Their noses are very powerful, with 200 million receptors—making their sense of smell about 14 times stronger than that of a human.

Here are five other interesting facts about a cat’s nose:

No two cat noses are the same. Just as every human has unique, one-of-a-kind fingerprints, each cat nose has distinctive patterns, lumps, bumps, and ridges that no other feline on the planet will share.
A cat’s nose and fur color match. Black cats will have black noses. Gray cats, gray noses. White cat, light pink noses. And multicolored cats usually have multicolored noses.
The skin around a cat’s nostrils is called nose leather.
A cat’s nose whets its appetite. Cats have very few taste receptors on their tongues. So, it’s their sense of smell that stimulates their appetite. If a cat can’t smell its food, it won’t want to eat.
Cats have a “second nose” located on the roof of the mouth called the vomeronasal organ. Rather than picking up regular scents, it detects pheromones which are important for mating, social interactions, territorial information, and more.

Hopefully this gives you a new (or renewed) appreciation for and understanding of your beloved pet. They are fascinating, amazing creatures, indeed!

References

10 Most Interesting Facts About Dogs’ Sense of Smell. 2018 Feb 28.
8 Dog Nose Facts You Probably Didn’t Know.
Kelley J. 8 Interesting Facts About the Cat Nose and the Cat Sense of Smell. 2017 Oct 13.