Paws for Thought: The Nose Knows

Smelling burnt toast or a rat, Molly’s nose knows best!

EDITOR’S NOTE: Dr. Janice Mitchell is a veterinarian with Island Animal Hospital and Little Current Veterinary Services, and a beekeeper too!

The Nose Knows

by Janice Mitchell

A friend recently shared an article about detection dogs being used in an airport in Helsinki, Finland to sniff out COVID-19-positive travellers through a swab from their armpit sweat. Immediately I thought, ‘if this pilot study proves effective, what a more cost friendly and gentler approach than the current nose-pithing PCR swab test?’ Apparently the dogs are very good at it and are being found to detect the disease five days before the patients get any clinical symptoms. A similar program started at Dubai International Airport over the summer. If research is successful, detection dogs could be deployed in airports or other venues to screen large numbers of people. According to Medical Detection Dogs, a charity in the UK, it is speculated that a single dog can screen up to 250 people per hour.

This is yet another skill on a dog’s curriculum vitae proving how amazing their nose is, and how they continue to help humans out. We know the list is long—from the conventional tracking, search and rescue, drug and banned foods detection, to the medical side of things, including detecting cancer, malaria, impending seizures in epilepsy, and low sugar levels in diabetics. Heck, they are even being used to detect bed bugs and invasive zebra mussels and are being used in conservation methods to identify floating whale poop. 

 How do they do it?

Dogs possess up to 300 million olfactory receptors in their noses, compared to about six million in us. And the part of a dog’s brain that is devoted to analyzing smells is about 40 times greater than ours. Their long muzzles (sorry, boxers) contain a labyrinth of thin bones, called turbinates, which are all lined by tissue containing these receptors. This provides a very large surface area for the air breathed to pass over. The dog also has a different site for a second separate sense of smell. It consists of two elongated fluid-filled sacs above the roof of the mouth. It is named the vomeronasal organ and it detects body scents or pheromones.

Dog’s snot—the classic doggy wet nose—is also an essential feature. The moisture caused by a covering of mucus assists in the collection of odour molecules. Odour molecules dissolve in the mucus and are transported in the air breathed in up to the olfactory receptors in the top of the dog’s nose. If there is not enough mucus the dog licks its nose. The average dog produces about two cups of mucus a day.

Dogs use sniffing to maximize the detection of odours. Sniffing consists of a series of rapid inhalations and expirations, normally three to 10, but possibly up to 30, during which the normal breathing mechanism is disrupted. Each nostril sniffs air from separate areas so that during sniffing there is a bilateral scent intake. To maximize the efficiency during sniffing the dog needs each sniff intake to be unobstructed. Consequently, the expired air is passed out through the slits at the side of each nostril creating an air turbulence and allowing new odours to be inhaled directly into the centre of each nostril.

All these amazing features in dogs make them more aware of smells in a way that humans cannot understand. And while theoretically all breeds of dogs should have this better sense of smell than humans, in practice, certain breeds and individuals of dogs are better candidates for scent detection work.  Generally, the longer nosed breeds tend to be much better with their sense of smell. The breeds commonly seen as fit for scent detection work include German shepherds, Labradors, poodles, and spaniels, partly because they have that better sense of smell, but they’re also dogs that are really trainable and really happy to work with humans.

What makes a scent? We constantly emit an aura of hundreds of volatile chemicals from our skin, our breath, and potentially even our gut microbes. Every smell is made up of a complex cocktail of compounds, like a recipe with multiple ingredients. Generally, these scents are too faint for us to detect, but to animals we are clouds of smells on legs, and they can detect when our odour is different from usual. This is vital, because scientists suspect that when we’re unwell our unique aroma changes; each disease could even have its own smell signature.

As a result, from studying the dog’s amazing smell power and the chemical signatures of diseases, scientists are working on developing electronic noses, or e-nose for short. This could be a future patch that you wear on your skin, or a wristband that changes colour when it detects chemicals in your sweat. Very Star Trek Dr. McCoy-like.

When researching this article, I also discovered a group in the US called K9 Nose Works. Essentially, mimicking professional detection work, this is a fun dog ‘sniffing’ sport for all dogs and people. This ‘sport’ can be another mental stimulation exercise for your dog, performed in your home, and include all our K9 friends who didn’t make the cut for the professional jobs.

Finally, some take home messages. Since our current testing methods seem overwhelmed and are taxing our health care system dollars (and thus our own pockets), perhaps we should taking note of what our Scandinavian friends are doing. And although technology is looking towards a synthetic nose, ‘happiness starts with a wet nose and ends with a tail.’ 

An inspiration: “The morning wind spreads its fresh smell. We must get up and take that in, that wind that lets us live. Breathe before it’s gone.” ~ Rumi.