By: Lâle Aksu
Canine Scent Detection Specialist, Program Lead – Training
Canines for Care Scent Detection Program
As a Manchester Terrier owner, I am often asked what the breed’s original job was. My answer: hunting and killing vermin. After all, they are called Manchester “Terrier.’Long ago, our breed’s development was driven by rat baiting sports. Bets were placed on how many rats a dog could kill in a specific time.Today, though we have gravitated away from these kinds of activities, our dogs still enjoy dog sports that stimulate their use of scent, like tracking, scent work, earth dog and barn hunting. Manchesters excel at these sports, but why is that?
First, let us look at the anatomy of their head and nose. Our breed standard says that a Manchester Terrier’s head should be “narrow, almost flat, with a slight indentation up the forehead, long and tight skinned. Slightly wedge, shaped, tapering to the nose, and well filled under the eyes, with tight-lipped jaws.
Nose should be perfectly black.” Their heads and instincts have been honed for the work they did. And they also adapt well. I often refer to their noses as the perfect needle-shape needed to fit into my pockets and rob me of my treats. But back to our investigation. Let us next look at how the sense of smell works in dogs in general. At the top of the olfactory system is the brain.
The olfactory lobe of a dog’s brain is very large compared to a human. This helps them to process the scent information they encounter in everyday life or for a specific job. But as important as the brain is, the working end of the olfactory system is the nose. Dogs have up to 300 million olfactory receptors in their noses, compared to just six million for humans. When they inhale through their nostrils, air separates into two distinct pathways. Approximately 12-13% of each breath travels through the upper flow path, which leads straight to the olfactory region.
Here, odour molecules are deposited andaccumulate, preventing them from being exhaled. In the lower pathway, the remainder of the air flows to the lungs. When that air is exhaled, it once again passes over the chemical receptors in the olfactory region, providing more exposure and information. Just like in humans, the nose can adjust airflow patterns during inhalation to collect separate odor samples in each nostril, allowing comparison of a smell’s intensity to help determine its location.
That brings us to…sniffing! Did you know that your dog has a favourite nostril? Dogs first start sniffing through their right nostril. Only if the smell turns out to be familiar or non-aversive (like food do they shift to using their left nostril. However, if the smell is novel, threatening or arousing (such as adrenaline), the dog will continue to use only their right nostril. Scientific studies indicate that this may be because the right hemisphere controls novel information processing and has a dominant role in the neuroendocrine system governing responses to stress, while the left hemisphere takes charge of behavioural responses to familiar stimuli.
So, what does this mean for your dog? Well, their sense of smell is very strong. Your dog can smell one tablespoon of sugar dissolved in two Olympic size pools of water. They also think about and process scent differently. Imagine the smell of a bowl of chilli. To you, it smells like one dish. Your dog, however, smells each of the ingredients: beef, tomato, salt, pepper, chillies, beans, etc. They also smell the pot it was cooked in, the bread on the counter, the spices in your cupboard, and the lasagna you cooked in the oven yesterday.
With training, they can use this special superpower to do amazing things like detecting bombs, cancer, drugs, and lost people. And even without training, you can watch their noses at work every day as take on tough challenges like digging treat crumbs from under the fridge or finding their toy under the couch.
So, take your buddy out for a walk and pay attention to how they react to the smells around you. I, personally, can watch them all day doing that and wish I could smell what they do for a day.
Learn more:
Lâle Aksu
Proud owner of Time4Dogs Boarding and Training

Scent Detection Specialist – Training Lead@ Vancouver Health