When I am stressed, it affects me not only mentally but physically. I can’t sleep, my shoulders ache and my stomach ties into knots. What I didn’t know until recently is, apparently, when I’m stressed, I stink too. Maybe not to you or me, but definitely to my dog Sueshi.
A few weeks ago, a study out of the Queen’s University Belfast in the UK found that dogs can detect stress in humans by smell. It turns out that when we are stressed, our bodies produce a different odor, one that dogs can easily pick up. The dogs in the study accurately detected stress 90 to 96.88% of the time, which is quite impressive.
Dogs have an extraordinary sense of smell. By some estimates, they can smell anywhere from 1,000 to 10,000 times better than their human guardians. Astonishingly, a dog’s nose has up to 300 million scent receptors compared to a human’s 5-6 million. The area of the canine brain related to smell is about 40 times larger than in a person’s brain.
Our canine companions “see” the world through their noses. With a quick sniff, dogs can instantly determine a fellow canine’s diet, gender, mood and health status. Dogs also remember smells and can identify dogs, people and places they haven’t seen in years.
Dogs have also been known to have the extraordinary ability to detect many types of cancer in humans by scent, including breast, lung, bladder, prostate and melanoma, to name a few. Examples abound on the internet of dogs tipping their owners off that something was amiss. A husky named Sierra went viral a few years back after she alerted her owner, Stephanie Herfel, to ovarian cancer on three separate occasions over the course of four years.
Sniffing out seizures before they occur is another fantastic feat our canine friends can perform. After decades of anecdotal stories of dogs alerting owners to an oncoming episode, in 2019 researchers confirmed that trained dogs could predict seizures by scent. Three of the five dogs participating in the study — Casey, Dodger and Zooey — identified the seizure samples correctly 100% of the time.
A dog’s extraordinary sense of smell goes beyond medical alerts; dogs can even detect human emotions. A recent study argues that dogs can smell happiness and fear in humans.
Remarkably, the study also claims that dogs mirror these human emotions in their own behavior. The dogs exposed to human fear scents showed more stress, had a higher heart rate and sought reassurance from their owners. On the flip side, those who sniffed happy emotions maintained normal heart rates, showed no signs of stress, and expressed interest in meeting strangers involved in the study.
A dog’s ability to tap into our emotions through their extraordinary sense of smell is perhaps why dogs make such good therapy pets.
For decades, certified therapy dogs and their handlers have been visiting hospitals and nursing homes to bring comfort to patients and residents. At Pasadena Humane, therapy dog (and cat!) teams help reduce stress in kids by participating in our humane education programming.
Reluctant young readers often find sharing a book with a pet less threatening than reading to a teacher or parent.
While these types of programs were scaled back during the pandemic, we are resuming our efforts to share the healing benefits of animal companionship through our Pet-Assisted Therapy program.
If you have a certified therapy pet and would like to get involved, please email email@example.com.
Dia DuVernet is president and CEO of Pasadena Humane.
This blog post originally appeared as a column in the Pasadena Star-News on October 8, 2022.