A University of Bristol study led by Dr. Nicola Rooney, with Zoe Parr-Cortes as a key author, in 2024 found that dogs can detect human stress and relaxation through smell and that stress scents changed how the animals behaved in an ambiguous task.

The research tested 18 dogs and placed them in a deliberately unclear situation to observe how human odors influenced decision-making. The setup included removing two familiar bowls and replacing them with a single bowl placed between the previous locations, creating an ambiguous choice for the animals. Scientists note that dogs process human emotions more functionally than many other animals, adapting their behavior based on visual and olfactory cues. This adaptability is crucial for understanding how they respond to stress in their human companions.

Dr. Zoe Parr-Cortes, a veterinarian and PhD graduate at the University of Bristol, said, “As one of our closest companions, dogs have co-evolved alongside humans for thousands of years.” The remark framed the study’s premise: that dogs’ long association with people might make them sensitive to subtle human signals conveyed by scent. Understanding their ability to detect human emotions through volatile organic compounds (VOCs) in sweat or breath, like stress hormones, can significantly improve training techniques, particularly for service dogs assisting individuals with PTSD.

The study examined responses to odors associated with human stress and relaxation and linked those scents to measurable shifts in the dogs’ behaviour. “While we don’t know what exactly dogs are smelling, we know that dogs can be trained to detect changes in cortisol in humans,” Dr. Zoe Parr-Cortes said, pointing to the biological pathways that may underlie scent-based communication between species. Additionally, research on canine olfaction shows that brain imaging reveals dogs’ strongest response to the scents of familiar humans, highlighting the powerful recognition and bonding capabilities that enhance their interactions with people.

Investigators used the ambiguous bowl arrangement to observe whether the scent conditions changed how willing dogs were to approach a location where a positive outcome was uncertain. In the researchers’ words, “Our findings suggest that the smell of stress may have reduced how willing the dogs were to take a ‘risk’ in a situation where a positive outcome seemed unlikely.” That result tied the olfactory cue directly to a change in the animals’ judgment under uncertainty. This insight emphasizes the importance of understanding that physical and emotional contexts can shape canine behavior in significant ways.

Beyond the immediate experimental task, the study noted broader capacities of canine noses. The authors wrote that dogs can sniff out cancer and diabetes, and even the zits on our faces, underscoring how finely tuned dogs’ olfaction can be and why scent remains a powerful channel of information for them. What other research has been conducted on canine olfaction and its impact on human interactions is also noteworthy.

Dr. Zoe Parr-Cortes closed with practical advice grounded in the study’s behavioral findings: “So, keeping your relationship with your dog happy and based on positive reinforcement and fun engagement is the best way to have a good relationship and a happy dog.” The comment linked the laboratory observations to everyday interactions between dogs and their owners, reinforcing the notion that understanding dogs’ emotional perceptions can enhance training and bonding experiences.

Readers interested in the original institutional announcement can find the University of Bristol’s summary of the work online. How do dogs process human emotions differently than other animals is a question worth exploring further.

Source

Original reporting: view the original article.