Do you know how a pug smells? If you’re expecting a discussion of the odor of a pug, that’s very simple: It depends on what the little critter has gotten into and how long ago he had his last bath. But today’s topic is the sense of smell.
Previously, I’ve focused on some health effects of the pug’s squished snout. That short snout also affects how well the pug can smell. That’s because the ability to detect odors is determined largely by the number of scent receptors in the nasal passages, and the number of receptors is largely determined by the size and length of the nose and snout; it’s a matter of the amount of space available for the receptors.
Obviously, a dog like the Basset hound has a bigger and longer nose than either the Boston terrier or the Pekingese, all shown below.
Basset photo above is from http://www.thehappywoofer.com/basset_hound.php.
Boston terrier photo above is from http://www.pets4homes.co.uk/pet-advice/health-issues-more-commonly-seen-in-the-boston-terrier.html.
Pekingese photo above is from http://www.yourpurebredpuppy.com/training/pekingese.html.
Dogs with larger noses and longer snouts have more nasal space and thus, room for more scent receptors. Therefore, such dogs are better able to distinguish smells than are dogs with smaller noses and shorter snouts – such as, of course, pugs.
For example, scientists have determined that bloodhounds, being large, with long noses, have about 300 million scent receptors. (Bloodhound photo above is from https://en.wikipedia.org/wiki/Bloodhound)
On the other hand, dachshunds, being small, but with long noses, have about 125 million scent receptors. (Dachshund in photo above is our pugs’ friend Benji, who is able to detect odors that they miss.)
Based on the facts above, I’d “guesstimate” that small, flat-nosed dogs like our pug Sarah may have as few as 100 million scent receptors. Here’s Sarah again (below), with a frontal view of her squash-nosed self:
Lest you grieve overly much for Sarah and her brachycephalic kin, bear in mind that in a sniffing contest between a pug and a human, the pug always wins. Humans have only 5 to 6 million scent receptors, compared to my “back of the envelope” estimate of 100 million for pugs. Sarah may not be able to track an escaped convict through the Everglades, but she always knows when my pocket contains an empty plastic bag that once held dog cookies.
And whenever a morsel of food rolls under the stove or anywhere else that her truncated snout can’t reach, our pug Sarah knows it’s there. She places herself in front of the offending appliance or furniture and “points” her unpointed nose in its direction until she can get a human (usually me) to fish out the crumb for her.
For more information about the dog’s sense of smell, read the chapter titled “Sniff,” pp. 67-88 in Inside of a Dog: What Dogs See, Smell, and Know by Alexandra Horowitz. (2009). Scribner.