Dogs have such a keen sense of smell that there are numerous jobs entrusted to them—including detecting diseases and infections like cancer and malaria, predicting migraines, assisting police and military forces, identifying criminals, and taking part in search and rescue missions. They are masters at tasks requiring an ability to identify scent because they have a 10,000-100,000 times heightened ability to detect odors in parts per trillion compared to human beings. How have canines developed this incredible skill and what unique aspects of their physiology enable them to achieve such difficult and amazing scent-related goals?

An Impressive Number of Receptors

Dogs possess up to 300 million olfactory receptors in their noses, compared to around six million in human beings. These receptors are neurons that extend into mucus in the nose and have tiny cilia (hairs) on the end. Moreover, the part of a dog’s brain that analyzes smells is around 40 times greater than that of human beings. Dogs additionally have a quality called neophilia (an attraction to new, fascinating odors). All this combined makes a dog’s sense of smell more powerful than any device or instrument made by human beings. Thus, a canine is able to detect substances containing concentrations of one part per trillion (equivalent to a drop of one substance in 20 Olympic-sized pools).

A Two-Chamber Process

Another feature of a dog’s olfactory system is that canines inhale air through two different chambers. A small amount of air goes into the olfactory center, which is filled with bony structures called turbinates. These ridges are covered with mucus membranes that provide a sizable surface area for the air to pass over. They essentially slow down the rate at which air enters the nose. Air is exhaled through the second chamber (the slits at the side of the nose). This system allows dogs to breathe in new scents while expelling old ones.

A Love of Exotic Smells

If you are out walking your dog and you notice they stop at a specific spot to smell it or return to it after having smelled other areas, it is because their system is so sophisticated that they may recall which nostril they smelled the original scent from. If they return to a spot, it may be because they wish to investigate the original scent with the other nostril. As mentioned, dogs love original scents, which is why some enjoy smelling dog-safe, therapeutic-grade essential oils like lavender, melissa, ylang-ylang, neroli, or sweet orange. Essential oils impact olfactory senses positively, which is why many human beings use them to improve focus, de-stress, or battle anxiety. Some dog owners also used vet-approved oils to help their dogs fight issues like sound sensitivity or anxiety in a natural way.

The Vomeronasal Organ

This organ, also known as Jacobson’s organ, forms a second olfactory system that dogs depend on. It is located at the base of the nasal passage and it identifies pheromones (the wide array of chemicals that different animals produce). This system has its own, unique nerves that connect up to a different brain area so they can be analyzed.

A dog’s sense of smell is a fascinating thing indeed. It actually relies on two separate olfactory systems that are connected to different parts of the brain. Thanks to the sophistication of these systems, dogs can complete unique tasks like scent tracking, the identification of explosives, and the diagnosis of diseases ranging from cancer to malaria.


About the Author: Now working as a writer, Jackie started her career as a veterinary nurse and has always been an animal lover –  but after becoming a mom refocused and decided to spend more time with her family. When she’s not writing, she volunteers for a number of local animal welfare charities and also has a menagerie of pets to look after, including a sparky whippet called Charlie.