Any dog owner will tell you—our furry friends seem to have a sixth sense when it comes to our emotions. Whether they give you space when you’re frustrated or snuggle up when you’re down, it’s clear they just know.
But how exactly do they pick up on our feelings? Are they reading our body language and tone of voice, or is there something deeper at play?
A new study published in PLOS One reveals that dogs don’t just observe our stress—they can smell it. When humans experience stress, their body chemistry changes, altering the scent of their breath and sweat. And dogs, with their incredible noses, can detect that shift.
“The take-home message of this study is that our bodies’ psychological stress response changes the smell of our breath and sweat and that dogs can detect this change,” said Clara Wilson, a Ph.D. student in psychology at Queen’s University Belfast, in an interview with Gizmodo.
Putting a Dog’s Nose to the Test
To test this theory, researchers collected sweat and breath samples from 36 volunteers before and after they completed a mentally stressful task—counting backward from 9,000 in increments of 17. (Yes, just thinking about that makes us sweat.)
Four specially trained dogs were then asked to distinguish between three scents: an unused gauze pad, a pre-stress sample, and a post-stress sample. The results? The dogs correctly identified the stress odor 93.5% of the time.
“This study provides further evidence of the extraordinary capabilities of ‘man’s best friend,’” Wilson said, according to NBC News.
More Than Just a Nose for Treats
While dogs rely on a mix of cues—body language, vocal tone, and scent—this research confirms that smell plays a crucial role in how they sense our emotions. Given that dogs can smell anywhere from 1,000 to 10,000 times better than humans, according to VCA Animal Hospitals, it’s no surprise they can pick up on even the slightest chemical changes in our bodies.
This discovery could have real-world implications, particularly in training service dogs to support people with anxiety or PTSD. If dogs can be trained to recognize and respond to the scent of stress, they could provide even more targeted emotional support.
So the next time your pup offers comfort after a tough day, remember—they’re not just being sweet. They actually know you're stressed… and they can smell it.