Why dogs’ smell sense is really fantastic

A dog's sense of smell is 1,000 to 10,000 times more powerful than humans. Their noses are lined with 300 million olfactory receptors.
In comparison, humans have a mere 5 million olfactory receptors. But dogs also inhale in short breaths up to 300 times a minute, meaning that their olfactory cells are constantly picking up new scents.
And possibly 30% of their brain is dedicated to analyzing odor. It is estimated that the percentage of a dog’s brain devoted to analyzing odors is 40 times larger than a human one.

The nose is formed by bones, muscles and soft tissue and includes a blood supply of arteries and veins plus nerves, which are connected to specialized areas in the brain.

When we are sick, we produce compounds that waft around us. In infectious or disease states, volatile organic compounds (VOCs) are emitted in breath, blood, sweat and urine, creating an‘aura’ of molecules around the human body. These VOCs often result in changes in body odor, which, studies have found, are detectable by dogs.