Dogs comfort us when we're sad or stressed, but they might be taking on some of our stress in the process. Here’s what you need to know.
Is Your Stress Stressing Out Your Dog? Here’s What a New Study Says
Updated Sep. 11, 2024
Sometimes I’ll be having a stressful phone call, glance at my dog Tux and see him staring at me intently. Other times, I’ll be frantically cleaning before dinner guests arrive and realize that he’s rushing around alongside me. If, like me, you’ve noticed your dog seems particularly attuned to your emotions when you’re feeling overwhelmed, you might wonder, Can dogs smell stress?
The answer to that question is yes. Numerous studies have shown that dogs can detect the stress hormone cortisol, but it hasn’t been clear whether that stress actually upsets them. A new study published in Scientific Reports may have the answer to your pooch’s level of empathy and reaction to your stress.
“I think it’s the first study that shows that the odor of human stress affects dogs’ emotional state—more specifically, how optimistic and pessimistic they are when they’re faced with an uncertain decision,” says veterinary surgeon Zoe Parr-Cortes, BSc, BVSc, MRCVS, the study’s lead researcher.
Read on to find out how your stress affects your dog’s behavior—and what it means for your dog and for you.
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How did researchers determine if dogs felt human stress?
To establish a baseline answer to “Can dogs smell stress?” for the purposes of the study, Dr. Parr-Cortes and her team taught 18 dogs that one bowl in a room held a food reward, and one did not—then timed how quickly each dog approached a third mystery bowl to see if it contained a food reward. That mystery bowl contained human breath and sweat samples from people who either completed stressful tasks like public speaking and math tests under pressure or engaged in relaxing activities like listening to soothing music and watching calming videos.
The researchers then gave the dogs a cognitive bias test to measure their emotional response to smelling these odors. Dr. Parr-Cortes compares this component of the study to an “Is the glass half full or half empty?” experiment. “If you show someone a glass that’s filled halfway, whether they think it’s half full or half empty is going to depend on their mood at the time or their outlook, that sort of thing,” she explains.
Instead of half-filled glasses, the canine study used food bowls to reveal how optimistic or pessimistic dogs felt. If dogs approached a mystery bowl quickly, it showed optimism about finding a food reward. But after smelling a jar with a stress odor—”short bursts just before each decision,” according to Dr. Parr-Cortes—the dogs were less likely to approach the bowl.
“It suggests that the stress smell might have decreased how willing dogs were to risk approaching that bowl,” she says. “They might have thought it was unlikely to have a reward in it, and it might have been a way for them to avoid being disappointed if they approached the bowl.”
Does human stress make a dog sad?
While it might seem like there’s a cause-and-effect relationship between stress and sadness, researchers can’t say for sure whether human stress actually makes dogs sad—at least in terms of how we would think of that word, according to Dr. Parr-Cortes. “We can’t directly measure emotions like sadness in animals because specific feelings like those can only be self-reported,” she explains. “As humans, we can assign different names to positive and negative emotions—sadness, anxiety, fear—and they make us behave differently.”
While we obviously can’t ask animals to name their feelings, we can assess their behavior and decisions to suggest whether they’re in a positive or negative state—and the study did find that after smelling human stress, the dogs entered a more negative state.
“We can say that they’re being pessimistic, or they’re being risk-averse, or they’re not wanting to risk something—which we know are associated with negative emotions,” Dr. Parr-Cortes says. “But we can’t know for sure whether that’s sadness, stress or being scared.”
What are the signs you’re stressing out your dog?
To figure out if your dog is exhibiting signs of stress as a result of your actions and mood, it helps to understand dog behavior, from the weird noises your dog makes to its facial expressions. Common dog stress signals include exhibiting whale eye (when the whites of the eyes are pronounced), licking their lips, yawning, averting their eyes, tucking their tail between their legs and flattening their ears. Dogs may also lick their paws when they’re anxious.
If you notice that your dog seems stressed, use it as a reminder to take a deep breath and try to reduce your stress levels before engaging with your pup—particularly before a training session. We can all use less stress in our lives!
How long are dogs affected by a human’s stress?
The study didn’t test how long dogs are affected by a human’s stress—simply whether they were immediately affected by smelling a jar with the scent of human stress. Each dog would smell the jar for 20 seconds before being released into the room with three bowls. “We know that a short exposure was enough to influence their response,” Dr. Parr-Cortes says, “but we don’t know how long these effects might last.”
It’s worth noting that in this study, the stress samples came from strangers—not the dogs’ owners. Separate studies published in Scientific Reports have found that popular herding dog breeds mirror the long-term stress levels of their owners and that long-term stress in dogs is related to the human-canine relationship and owners’ personality traits.
How can you help your dog feel less stressed?
A couple important ways we can help decrease dog anxiety and stress are by using only positive training methods, which involve rewards instead of punishment, and training our pets when we’re feeling calm, according to Dr. Parr-Cortes. In fact, she says the study is a reminder of how close dogs and humans have become; our moods affect one another. She’s personally witnessed it in her relationship with her dog, Darwin, a retired racing greyhound.
“It’s quite fascinating that, as species, we’ve become this close. I think it’s just important to appreciate that emotional intelligence—that dogs seem to have both negative and positive emotions,” she says. “So I think the main takeaway is to be considerate and compassionate about your dog’s emotions, avoid negative punishment and increase your positive, fun interactions. Go do something fun with your dog, and it’ll make you both feel better.”
Try taking a long walk with your pup, visiting a local pet store to pick out a toy or treat, engaging in a proper play session or even giving your dog a puzzle toy to figure out while you engage in some R&R.
Do dogs smell other emotions?
Since we know dogs can smell stress, it’s natural to wonder, Can dogs smell emotions? Sure enough, dogs can smell emotions like anger, happiness and fear, and their behavior will change in response. This intuitive species can take cues from scent and other clues like our body language, facial expressions and vocal tones. Empathy may also be at play; another recent study published in Animal Behaviour found dogs became stressed listening to recordings of humans crying.
Dr. Parr-Cortes hopes to expand on her research in the future. “I think moving forward, it would be interesting to test things like happiness odors or really deep-relaxation human odors on this cognitive bias test and see if that has a positive effect on their mood,” she says.
As a former therapy-dog handler, I spent five years visiting hospital patients with my Labrador retriever mix, Rio. My loving, loyal dog seemed to intuitively know when to calmly lay his chin on a patient’s knee when they were feeling sad and when to wiggle with excitement to meet a happy child—whatever would offer the most comfort in any situation. So even as science continues to expand our knowledge of dogs, there’s something special about the power of the human-canine bond that I’m not sure can be quantified.
Ultimately, what dogs want is often what we want: to be happy together. Can dogs smell stress and be negatively affected by it? Yes. Does spending time with dogs decrease our stress? Of course (and science proves it)! So do yourself and your dog a favor and spend as much time as you can unwinding from daily stress by exercising, playing and relaxing together.
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At Reader’s Digest, we’re committed to producing high-quality content by writers with expertise and experience in their field in consultation with relevant, qualified experts. For this piece on whether dogs can smell stress, Jen Reeder tapped her experience as a longtime pet journalist, the former president of the Dog Writers Association of America and a dog owner. We rely on reputable primary sources, including government and professional organizations and academic institutions as well as our writers’ personal experiences where appropriate. We verify all facts and data, back them with credible sourcing and revisit them over time to ensure they remain accurate and up to date. Read more about our team, our contributors and our editorial policies.
Sources:
- Zoe Parr-Cortes, BSc, BVSc, MRCVS, veterinary surgeon, contributor to Olfactory Research in Dogs, PhD candidate in clinical veterinary science at Bristol Veterinary School at the University of Bristol in Langford, England; Zoom interview, Sept. 4, 2024
- Scientific Reports: “The odour of an unfamiliar stressed or relaxed person affects dogs’ responses to a cognitive bias test”
- Frontiers in Allergy: “Can scent-detection dogs detect the stress associated with trauma cue exposure in people with trauma histories? A proof-of-concept study”
- PLOS One: “Dogs can discriminate between human baseline and psychological stress condition odours”
- Scientific Reports: “Long-term stress levels are synchronized in dogs and their owners”
- Scientific Reports: “Long-term stress in dogs is related to the human–dog relationship and personality traits”
- Animal Cognition: “Interspecies transmission of emotional information via chemosignals: from humans to dogs (Canis lupus familiaris)”
- Animal Behaviour: “Family pigs’ and dogs’ reactions to human emotional vocalizations:a citizen science study”
- PLOS One: “Psychophysiological and emotional effects of human–Dog interactions by activity type: An electroencephalogram study”
Originally Published: September 11, 2024
