Cold, wet, nudging, sniffing, snoring… Your kerry’s nose never stops working. And it has a lot of work to do! A human has up to 5 million olfactory receptors, but some dog breeds can have up to 300 million, studies have shown.
What this translates into, as Alexandra Horowitz has written in her book, Inside of a Dog (Simon and Schuster, 2012) is this: “We might notice if our coffee’s
been sweetened with a teaspoon of sugar; a dog can detect a teaspoon of sugar in a million gallons of water, or two Olympic-sized pools.”
This wondrous nose power comes from the structure of a dog’s nose and muzzle, a masterpiece of thin bones, muscles and soft tissue, and aerodynamics, all
connected to specialized areas in the brain.
The human nose has some of these features, of course, but dogs have evolved sniffing to far higher level. While humans make long inhales and exhales through
the same nasal pathway (we breathe in and out through the same channel), dogs inhale and exhale about five times per second and have separate olfactory
and respiratory routes in their noses. The front part of a dog’s nose is almost entirely devoted to respiration (and heat exchange), while the rest
is devoted to sorting out smells. On each sniff, a dog’s nostril flares open and sends air back to a specialized olfactory center in the muzzle. When
the dog exhales, he blows air out of the slits in the sides of the nostril, which stirs up air flow and allows the dog to process even more of a given
More evidence of how much attention Mother Nature has paid to the canine nose? Just ask a newborn puppy. A newborn kerry may not be able to see or hear, but researchers have shown that a puppy has heat sensors around his nostrils that allow him to detect the infrared energy that radiates from warm objects such as Mom and Mom’s breakfast, lunch, and dinner buffet.
One thing dogs can’t do is sniff and pant at the same time, though – which is why your kerry will stop panting if you hold a treat or other interesting object up to her nose. She’s switching from respiration to olfactory, so as to check out the new object for scent processing, labelling, and recognition. This is why dogs have a harder time following scents in very hot weather or when they’re very fatigued.
For those situations where the sensitivity of a canine nose is needed but the working environment isn’t safe for a dog, due to heat or other environmental hazards, dog noses can still claim fame; engineers use computer-generated models of dog noses and muzzles to design mechanical “sniffers” – another example of recognizing that the dog nose knows!