Dogs can sense when humans are stressed, and this can cause them to feel down, too, new research shows. A study led by the University of Bristol, published in Scientific Reports on July 22nd, tested how the smell of human stress affects dogs.
Humans often react to the stress of others without even realizing it. Researchers at Bristol Veterinary School wondered if dogs might react in the same way. They wanted to determine if dogs’ learning and feelings change when they smell human stress or calmness.
Their findings suggest that dogs do indeed react to human stress smells, and they make more unfavorable choices as a result.
Based on a test of optimism or pessimism in animals
Researchers used a test to see if dogs felt positive or negative emotions. This test is based on how people’s optimistic or pessimistic choices show their emotions.
They recruited 18 dog-owner pairs for the study. The dogs took part in trials in which various human scents were key. During these trials, the dogs were trained to learn that a food bowl in one spot had a treat, but in another spot, it was empty.
After learning which bowl had the treat, dogs would quickly go to the bowl with the treat so as to avoid the empty one. Researchers then placed bowls in new spots between the original locations to see how the dogs reacted.
Peaceful you, positive pup: how your mood may affect your dog's optimism & learning
Our researchers Dr Nicola Rooney, @ZoePC5
show how dogs "sniff out" human stress & show how it affects their emotions, leading them to make more pessimistic choices.pic.twitter.com/dwoxLEDRGc
— University of Bristol (@BristolUni) July 22, 2024
If a dog quickly approached these new spots, it showed optimism, expecting food and thus indicating a positive emotional state. A slow approach showed pessimism, or the expectation of no food, thus indicating a negative emotion.
These tests were done with each dog being exposed to no odor, the smell of sweat, or breath samples from humans who were either stressed (from doing arithmetic) or relaxed (from listening to calming sounds).
Researchers found that the smell of stress made dogs slower to approach the new bowl location closest to where the empty bowl had been. This did not happen with the smell of relaxation. These results suggest that the stress smell made dogs more likely to expect no food in the new location, similar to the nearby empty bowl.
Pessimistic response reflects a negative emotion
Researchers believe that dogs’ pessimistic responses show they are feeling negative emotions. This might help them save energy and avoid being let down.
The team also found that dogs got better at telling which bowl had food and which didn’t. They learned even faster when they smelled stress.
Dr. Nicola Rooney, a senior lecturer in Wildlife and Conservation at Bristol Veterinary School and the lead author of the study, explained the significance of the findings. She said that understanding how human stress impacts dogs’ well-being is crucial, especially for dogs in kennels, companion dogs, and working dogs, such as assistance dogs for handicapped individuals.
