THE DOG’S NOSE

sniffs out the power of your dog’s nose

Humans are visual creatures. Our reliance on vision masks our
other senses, and only when we cannot see do we realise just how
poor those senses can be. A dog’s primary sense is olfaction, the
sense of smell. Their ability to detect odours puts ours to shame;
it is said to be up to 100,000 times stronger, detecting odours we
find completely undetectable. Dogs can detect chemicals with
subtle differences in structure at concentrations of just one p art per trillion...
yes, trillion! To put that into perspective, imagine laying out a line of dollar
bills between the earth and the sun and asking a dog (suitably attired for
space!) to find the odd one out. Or how about being able to smella person
who is 20km away? Their sense of smell is truly beyond our comprehension;
we can detect nothing with such amazing finesse, which makes me consider
the efficiency of my washing machine when my dogs are just as interested in
doggie scents on freshly laundered items; as dirty ones!
Given this incomprehensible ability, it’s not surprising dogs can be trained
to sniff out a huge variety of substances, from narcotics to pla nts to chemicals
produced by medical conditions. Dogs can detect distinct odours a ssociated
with cancer cells, identifying the disease from bandages covering skin cancers,
tissue samples or a person’s breath. They can recognise blood sugar changes

 

“The whole world comes

to your dog in that subtle

twitch of snout and

flaring nostrils.”

 

in a diabetic person before they are aware of symptoms and
warn of a seizure some 15 to 45 minutes before the affected
person is taken ill. Dogs are already being trained to detect
people infected with COVID-19. Initial results show an
accuracy of 94% and success even with asymptomatic cases.
Models suggest two dogs could screen 300 people in half an
hour, improving significantly on current methods.*
Opportunities to stand and scent are the canine equivalents
of an eagle riding high on air currents, searching for dinner
thousands of feet below. Or a person standing on a mountain
top on a glorious, clear day, viewing with crystal clarity every
tiny detail of the 360-degree panorama presented below. With
no need to travel or even exert themselves, the whole world
comes to your dog in that subtle twitch of snout and flaring
nostrils. The faintest breeze carries a wealth of information
we can only dream of imagining. What is it about their noses
that make them so incredibly powerful?
A fantastic product of evolution, your dog’s nose has unique
anatomy designed to optimise scent detection, even against a
background of competing smells. Each nasal cavity contains
three ‘turbinates’, convoluted structures that increase receptor
cells’ space. These specialised cells support hundreds of tiny
hairs, called cilia, which further enhance scent detection.
As breeds vary considerably in the size and shape of their
snouts (think German Shepherd compared to pug!), the
number and type of receptors differ too. This means dogs
are not all alike in their ability to detect scent. However,
even the worst-equipped canine is amazing compared to
humans, who have far fewer receptor cells and a meagre 25
hairs on each.
Canine noses employ specialised airflow to enhance
their abilities even further. Air enters each nostril from the
front and is exhaled to the side. Nostrils operate separately,
allowing dogs to locate smells in the same way our eyes help
us see in three dimensions and judge distance. The left nostril,
connected to the left side of the brain, is used to sniff familia r
scents and fun stuff, like food. Their right nostril connects
to the right side of the brain, where threats are processed.
This one is used for sniffing other dogs and potentially
worrying stuff.
I have often wondered why, if their sense of smell is so
powerful, I have to be thoroughly sniffed by pushy noses
whenever I come home. Sniffing (as opposed to breathing
or panting) enhances your dog’s ability to detect an odour.
Making physical contact helps, too, as scent molecules
dissolve in the chilly dampness and transmit directly to the
receptor cells. Dogs only really smell things to their full ability

 

in short huffs, with the mouth closed. This also explains how
they cope with living in our highly-fragranced homes, awash
with a heady potpourri of fragrance from cleaning products,
laundry liquids and our own unique combination of personal
hygiene and perfume choices. Each sniff takes in about 30mls
of air (two tablespoons). By splitting this air between odour
detection and breathing, your dog can scent continuously,
regardless of whether they are breathing in or out.
No wonder they can seem to sniff for so long!
In addition, your dog’s snout has a
special site called the vomeronasal
organ, which detects signals from
chemicals relating to behavioural
and physiological changes. Messages
from cells detecting these scents
are passed to the olfactory bulb
and then to the olfactory cortex,
which connects to the limbic system
in the brain. The oldest part of the
brain, in evolutionary terms, this area
is responsible for memory, motivation and
behaviour, explaining why scents can be so
important to your dog. In fact, in the same way, that
certain fragrances can bring back strong, evocative memories
for us, research has shown that scent can help dogs recall
memories formed in its presence. This is called associative
memory, a concept first described in the 1800s. It is thought
dogs create olfactory ‘images’, linking odour with specific
objects. Certainly, suppose they are following the smell of
one person and find a different one. In that case, they appear
confused, suggesting they have a scented expectation of what,
or who, they anticipate finding.
Your dog’s sense of smell can be affected by stress,
exercise, being unfit and their meal routine. The amount
of food, fat content and timing of meals all have an impact.
Air conditions are also important, with cooler or humid air
carrying aromas more strongly. Is this why my dogs love to
root around and snort in the snow, stuffing their
snouts deep into powdery, white drifts and
inhaling every delicious odour? Alexandra
Horowitz’s theory that dogs can even
smell time, based on the idea that scent
changes over time. This is borne out
by the ability of trained sniffer dogs
to recognise the direction humans
take along a trail, from as few as
five footsteps. While environmental
conditions affect the release of odour,
incredibly, trained dogs can still detect
the minuscule differences between the
footprints. By contrast, untrained dogs are
more likely to look for clues elsewhere rather
than use their nose.
It is known that humans are influenced by scent; our
thoughts and actions are affected by our feelings about a
particular aroma. For better or worse, odours affect mood
and emotions and shape our behaviour. Marketing managers
use this to their advantage, knowing the right fragrance can
tempt us to make impulse purchases... and the wrong smell
will make us leave their shop pretty quickly! For our dogs,

 

“Your dog’s sense of smell
can be affected by stress,
exercise, being unfit and
their meal routine.”

“Time spent sniffing interesting smells may
enhance the mood of any canine, boosting their
emotional health and wellbeing.”

scent can also trigger emotional memories. Sniffing prompts
your dog’s brain to produce dopamine, a chemical linked to
the experience of pleasure and rewards. This boosts their
ability to concentrate and increases motivation.
The formation of associative memories relies
on special cells controlled by dopamine,
so combining positive experiences
with certain fragrances can heighten
the effect. It is known that breeds
vary in their baseline levels of
dopamine, which could be why
dogs vary in understanding
and responsiveness to training in
scent work.
Combining odour with search
tasks increases success, even when
dogs are asked to find something
with a distinct odour, such as food.
The association with a specific smell
creates a stronger memory and enhances
learning. Sadly, scent can also become associated
with difficult memories, such as a trip to the vet or a stay at a
boarding kennel. In these instances, as scent can elicit precise
and accurate memories, a scent that has become linked
to a traumatic experience could be used to begin careful
desensitisation of a dog to that trauma. Providing your dog
with something that smells familiar can help them when
away from home. Time spent sniffing interesting smells may
enhance the mood of any canine, boosting their emotional
health and wellbeing.
Linking a certain aroma with positive
events can support training or relaxation
for our furry friends. The scent might
be used to enhance the effect of
positive events on your dog. Why
not incorporate scented materials
into enrichment activities to boost
its benefits, a perfect solution for
dogs who become over-excited
about food or need to watch
their waistline. Or bring materials
indoors to your housebound dog
to enrich their world until they can
venture out. Harness the power of
smell for your picky eater or poorly hound;
include strong-smelling titbits and warm the
food to release tempting aromas that may inspire
your pooch to eat. However you use scent with your canine
companion, it’s undoubtedly a world worth exploring.