Have you ever stood at the end of the lead while your dog investigates one small patch of grass for what seems like an eternity? You’re ready to move on, but your dog clearly isn’t. That patch of grass might not look terribly interesting to us, but to a dog it’s full of information.
That raises a question I find fascinating: can a dog breathe in through one nostril and out through the other at the same time? Not quite. What happens is more clever than that, and it helps explain why Labradors, Beagles, Spaniels, German Shepherds and dogs of all shapes and sizes are so good at finding smells we don’t even notice.
Can dogs sniff in through one nostril and out through the other?
Not as a normal sniffing mechanism. Research into canine nasal airflow shows that a dog takes in odour-bearing air through the nostrils, and during exhalation air is directed outwards and sideways through the openings beside the nostrils. The dog does not simply dedicate one nostril to breathing in and the other to breathing out.
Those outward-directed jets are important. Rather than blowing the interesting smell straight away, they can stir the surrounding air and help bring fresh scent molecules towards the nose for the next sniff. Meanwhile the two nostrils collect slightly different samples, which may help the dog work out which direction an odour is coming from.
The scientific work by Craven, Paterson and Settles included a computer model developed from the nose of a Labrador Retriever cross. Their 2010 research on the fluid dynamics of canine olfaction gives us a remarkable look at what is happening when a dog has its nose down.
How often does a dog sniff?
When they’re investigating something interesting, dogs can sniff several times a second. A rate of around five sniffs per second has been used in detailed research models, although the actual rate changes with the individual dog, its size and what it’s doing. This rapid sniffing is quite different from normal, relaxed breathing.
How much better is a dog’s sense of smell than ours?
You’ve probably read that a dog’s sense of smell is 10,000 to 100,000 times more sensitive than a human’s. You’ll find that range quoted in scientific reviews too, but it needs a bit of explanation.
It isn’t a single number that applies to every dog and every smell. Sensitivity depends on the particular chemical, its concentration, the dog’s health, anatomy and experience, and the way the test is conducted. A dog may detect some substances at concentrations far below what a person can detect, but that doesn’t mean every dog is exactly 100,000 times better at smelling everything.
The more useful point is that a dog’s nose is specialised for detecting and distinguishing odours that may be practically invisible to us. For a closer look at the commonly quoted figures and their limitations, see this scientific review of canine olfactory function and research discussing why sensitivity varies by substance.
What is inside a dog’s nose?
A dog’s nasal cavity contains intricate folded structures called turbinates. An area further back in the nose contains specialised olfactory tissue with sensory cells that respond to odour molecules. Airflow during sniffing helps deliver those molecules to the parts of the nose designed to analyse them.
Dogs also devote substantial nervous-system resources to processing smells. Smell isn’t simply a more powerful version of our own experience. It’s a major way dogs investigate their surroundings.
Why can dogs smell where something has been?
Imagine another dog has walked past a particular tree earlier in the day. Your dog may investigate traces left behind, along with smells from plants, soil, people and other animals. Air movement, temperature, rainfall and the nature of the surface all affect how odours travel and persist.
Dogs can also compare scent information arriving at each nostril, rather like we use information from both ears to locate a sound. The comparison isn’t magic and it doesn’t mean a dog always knows precisely what happened, but it is part of a very sophisticated sensory system.
Are Labradors the best dogs at smelling?
Labradors are excellent scent workers. They are often chosen for detection work not only because they have a capable nose, but also because many are enthusiastic about searching, working for rewards and cooperating with handlers.
They aren’t the only ones. Beagles and Basset Hounds have a long history of following scent trails. Bloodhounds are famous for tracking. Springer Spaniels and Cocker Spaniels are used in a variety of detection roles. German Shepherds, Belgian Malinois and other working breeds can be very effective scent dogs too.
And don’t underestimate your family pet. A Cavoodle, Border Collie, Terrier, Greyhound or mixed-breed dog can also enjoy scent games. Breed and head shape influence how dogs investigate odours, but individual motivation, confidence, health and training matter enormously. We shouldn’t assume that every member of one breed will outperform every member of another.
Why does my dog stop to sniff everything on walks?
We often measure a walk by the distance we’ve covered. Dogs don’t necessarily see it that way. When your dog stops to investigate a tree or patch of grass, it may be gathering information about its environment.
I encourage owners to give their dogs sensible opportunities to sniff. That doesn’t mean allowing them to drag you from one smell to another, or ignoring good lead manners. We can teach dogs to walk politely and also give them time to explore. A simple cue such as “go sniff” can help them understand when it’s their opportunity to investigate.
Some walks can be more about exploration than kilometres covered. That can be particularly useful for dogs that don’t need more frantic exercise but would enjoy an interesting, manageable outing.
Can sniffing help a dog relax?
Appropriate scent activities can offer enrichment, encourage natural foraging and give dogs opportunities to make choices. For some dogs, a quiet search activity is a lovely alternative to constant high-energy games.
But we need to be careful about overclaiming. Sniffing isn’t a cure for anxiety, and there isn’t a reliable universal formula saying that a few minutes of sniffing equals a certain amount of walking. What suits one dog might not suit another.
If your dog struggles with fear, barking, reactivity or being left alone, scent activities might be one useful part of an individual plan. They shouldn’t replace addressing the underlying behaviour. That’s where our in-home dog behaviour consultations can help.
Five easy scent games for puppies and adult dogs
1. Find the treat
Start by dropping a small treat where your dog can see it. Say “find it” and let them investigate. Gradually hide the treat in slightly more challenging but accessible places. Keep the early searches easy so your dog enjoys succeeding.
2. Scatter part of dinner
Scatter a portion of your dog’s regular food on a clean, safe patch of lawn, and allow them to find it. Our Treat Scatter Magic article explores this form of enrichment in more detail. Keep an eye on what else might be in the area, and avoid shared spaces where unsafe substances may be present.
3. Try a snuffle mat
Hide a few pieces of suitable food among the fabric strips. Supervise your dog and remove the mat if they start chewing or swallowing the material.
4. Search the boxes
Place a treat in one of several open cardboard boxes. Encourage your dog to search and make the game a little harder as their confidence grows. Use boxes without staples or other hazards, and supervise dogs that like eating cardboard.
5. Find a favourite toy
If your dog loves toys more than food, hide a toy somewhere easy, encourage them to find it, then celebrate with a game. You can gradually increase the difficulty without making it frustrating.
What about puppies?
Puppies are curious, and safe scent games are a simple way to encourage exploration. Keep sessions short, positive and appropriate to the puppy’s confidence and developmental stage. Young puppies don’t need complicated challenges. A few easy searches in a familiar, safe room are plenty to begin with.
Remember that enrichment doesn’t replace suitable socialisation, rest or learning everyday skills. Families wanting support can explore our puppy school and puppy pre-school in Brisbane or book a puppy setup session to establish good habits from the beginning.
Can scent games help with chewing, digging and barking?
Sometimes. A dog with too little to do may benefit from more appropriate outlets for searching and foraging. But chewing, digging and barking can also have other causes, including fear, frustration and separation-related distress. Simply giving the dog a puzzle feeder won’t resolve every behaviour problem.
Look at when the behaviour occurs, what happens immediately before it, and how your dog seems to be coping. For persistent problems, an individual assessment is more useful than guessing.
Can dogs smell our emotions?
Dogs can detect a range of chemical cues, and researchers have examined their responses to human stress-related odours. They also read our posture, movement, voice and other signals. That doesn’t mean they can read our minds or know exactly why we’re upset.
We’ve covered this subject separately in Dogs Can Smell Your Feelings. It’s a fascinating example of why we should look at the whole dog, rather than attributing every response to one sense.
Do wet noses work better? What about older dogs?
Moisture plays a role in capturing some odour molecules, but a wet nose isn’t a reliable test of health. An otherwise well dog can have a dry nose. Older dogs may also experience changes in their ability or willingness to investigate smells, and health conditions can affect scent performance at any age.
If you notice persistent nasal discharge, bleeding, swelling, noisy breathing, breathing difficulty or a sudden change in smell-related behaviour, speak to your veterinarian. These are health matters, not simply training problems.
Frequently asked questions
Can a Labrador sniff in through one nostril and out through the other?
Not in the way people often imagine. Dogs take in odours through their nostrils and direct much of their exhaled air sideways. The two nostrils can gather slightly different scent information, helping with odour investigation.
How many times stronger is a dog’s nose than a human’s?
The often-quoted estimate is 10,000 to 100,000 times more sensitive, but it isn’t a universal measurement. It varies with the odour, the dog and the testing conditions.
Which breeds are good at scent work?
Labradors, Bloodhounds, Beagles, Basset Hounds, Spaniels, German Shepherds and many other breeds can excel at particular scent tasks. Mixed-breed and companion dogs can enjoy scent games too.
Is it good to let dogs sniff on walks?
Yes, when it’s safe and appropriate. Sniffing allows dogs to explore. It’s entirely possible to combine sniffing time with polite walking and sensible boundaries.
Can sniffing tire a dog out?
Scent searches can be mentally engaging. How tiring they are depends on the activity and the dog. We shouldn’t treat sniffing as a direct replacement for all physical exercise.
Can puppies play scent games?
Absolutely. Begin with easy, short searches using safe food or toys in a familiar environment, and gradually build confidence.
Final thoughts
Next time your dog stops to investigate something that looks completely uninteresting to you, remember there’s probably a lot more happening than we can appreciate. Their nose is one of their greatest tools for understanding the world.
Good training isn’t about preventing dogs from doing everything that comes naturally. It’s about helping them live comfortably with us while giving them suitable outlets for normal behaviour.
If you’d like help with your puppy, loose-lead walking or behavioural concerns, the team at Jordan Dog Training works with dogs and their owners across Brisbane. Have a look at our puppy school and puppy pre-school in Brisbane or in-home dog behaviour consultations, or get in touch to discuss what would best suit your dog.
Research and further reading
- Craven BA, Paterson EG and Settles GS (2010). The fluid dynamics of canine olfaction. Journal of the Royal Society Interface.
- Jenkins EK, DeChant MT and Perry EB (2018). When the Nose Doesn’t Know: Canine Olfactory Function Associated With Health, Management, and Potential Links to Microbiota. Frontiers in Veterinary Science.
- Lippi G and colleagues. The olfactory fingerprint: can diagnostics be improved?