Dogs can smell whether you are stressed or calm and adjust their behaviors in response

Have you ever noticed your dog acting differently when you feel bad? It’s because dogs can smell your stress.

A new study from the UK says dogs can tell if you’re feeling stressed or calm just by smelling you. They watched 18 dogs to see how they acted around people who were stressed or relaxed.

The researchers made people feel stressed and then put their sweaty clothes and food bowls near 12 dogs. They wanted to see how the dogs would act when they smelled the stress.

“Some people have looked at, can dogs detect differences in odor. And they have. But nobody had looked at how that affects the dog’s emotions,” Dr. Zoe Parr-Cortes, the study’s lead author, told NPR.

Dogs can smell your stress after being trained to detect cortisol, a hormone that rises with stress. Service dogs do this for people with certain health conditions.

Researchers, however, wondered how smelling these cortisol changes might affect dogs’ emotions.

“Being a species that we’ve lived and co-evolved with for thousands of years, it kind of makes sense that dogs would learn to read our emotions because it might be helpful to them to know if there’s something threatening in the environment or some stressor that they need to be aware of,” Parr-Cortes explains.

The scientists studied the dogs’ reactions by testing people the dogs weren’t familiar with.

These people gave a quick, surprise speech and tackled tricky math problems while the scientists kept a straight face to make them anxious.

Afterward, the people chilled in a comfy chair and watched a peaceful video of nature scenes.

The scientists checked how stressed the people were by measuring cortisol, heart rate, and how anxious they felt. They also collected breath and sweat samples from the volunteers.

Meanwhile, they trained 18 dogs from different breeds to recognize the location and contents of several bowls in the testing room.

Parr-Cortes compares this setup to the test where people decide if a glass is half full or half empty, noting that their answer can vary depending on their mood or outlook.

First, the dogs learned that one bowl had food and the other was always empty. They got good at going to the food bowl and staying away from the empty one.

Then, the scientists removed the two bowls and put a new bowl in the middle. This made things tricky.

“Do they approach quickly, optimistic that there’s going to be a food reward in there, or do they approach more slowly, with a more pessimistic outlook that there might not be food in that bowl?” Parr-Cortes says of the dogs.

The scientists used sweaty clothes to test the dogs. The owners let their dogs smell the clothes before putting a bowl before them.

They did this with clothes that smelled like stress and calm, mixing up the order each time.

After smelling the stressed smell, the dogs were more unsure about going to the middle bowl. This showed they were less sure about finding food there. The calm smell didn’t change their behavior much.

Parr-Cortes says this might mean the smell of stress changes how dogs handle tricky situations. It could make them less likely to try something new if they think it won’t work out.

Molly Byrne, a researcher studying how dogs think at Boston College, thinks the study is really interesting.

She says we still need to learn more about how dogs understand things and that things like their past experiences can change their actions.

She thinks the study shows dogs might be less excited about good things if they know their owner is sad, which makes sense.

“When your owner is training you, they’re probably not giving you maybe as many treats if they’re really stressed,” Byrne says.

What does this mean to dog owners?

Parr-Cortes says rewarding dogs for good behavior strengthens the bond between owners and dogs.

The study also suggests that stress during training can make dogs feel bad and learn less.

She says this shows how dogs are sensitive to how you feel. To have a good relationship and a happy dog, it’s best to be positive and playful with them.

Byrne says getting upset while training a dog can make the dog stressed, too. It can make small problems seem bigger when you’re not calm.

The study used people the dogs didn’t know, so we know that dogs react the same way to different people, not just the ones they live with.

This is helpful for everyone who has a dog or wants to understand them better.

Byrne also thinks if something makes you feel scared or worried, it might make your dog feel that way.

For example, your dog probably isn’t if you’re not a big fan of crowds.

“If you’re stressed, you’re probably more likely to be tense and not as patient,” she adds. “[And it] might literally make them have different behaviors. I think that’s really, really important to know.”

Parr-Cortes points out that all dogs can be impacted by stress, even if they don’t show it.

She uses her calm retired greyhound, Darwin, as an example, saying that his obvious relaxation doesn’t mean he’s unaffected by her stress.

She explains that while humans depend on sight, dogs use their sense of smell to understand the world, which offers them a different perspective.

This emphasizes the importance of controlling stress around dogs and in general.

Here’s Dr Zoe Parr-Cortes talking about how stress odor affects dog behavior: