We catch our pups sniffing around park benches, other dogs' butts, our unmentionables—pretty much any place they can stick their noses into. Clearly their sense of smell is hypersensitive (and they gravitate towards particularly stinky things.) But we had no idea just how intense it was until we read Alexandra Horowitz's Being a Dog: Following the Dog into a World of Smell, where she shares exactly how dogs navigate the world through their schnoz. We’ve sniffed out a few of the most fascinating facts:
Dogs smell separately with each nostril, which allows them to detect the location a smell is coming from—it's essentially peripheral smell (like our peripheral vision.)
Some dogs can detect their owners' falling glucose levels and imminent seizures; others have sniffed out cancer volatiles in people's skin, urine, and breath.
The smell of a human is so strong to dogs that they can follow it over time, even through water: The odor rises to the surface of the body of water allowing the dog to detect the scent.
Dogs can smell and detect a trillionth of a gram of an explosive.
Dogs use smell to tell the time of day, determining it by the concentration of the scent in the air. Depending its strength, they can figure out how long it has been there.
Dogs have 300 million olfactory receptors compared to the six million in humans.
The Vomeronasal organ (VNO) in dogs' noses detects all hormones humans and animals naturally release, thus alerting them to various emotional states.
Dogs exhale through the side slits of their nostrils, so they keep a continuous flow of inhaled air in their snout for smelling.
Many of a dog’s identifying smells are in the anal glands, which explains why they're constantly sniffing each other there! The glands also transmit how a dog is feeling (anxious, playful, etcetera.)
Licking allows dogs to absorb molecules for smelling. They are licking the scent molecules off of their nose or your body to learn more about their environment.