Dogs are regarded as man’s greatest friend for various reasons, including protecting our houses from intruders, guarding us against danger, or just because they make the best companions and little sunshine balls. Dogs are exceptional communicators, unlike any other animal species. They can interpret our facial expressions, discern our emotions, and even follow our pointing gestures. They appear to have a gift for understanding our emotions to the hilt.
Additionally, a new study suggests that this “man’s best friend” may smell when you’re anxious, much like any excellent friend who can instantly tell how you feel without even asking. The body emits chemical messages called odors, developed primarily for communication within species. Researchers questioned whether dogs could detect chemical signals to react to their owners’ mental conditions given their extraordinary sense of smell, close history of domestication with humans, and use to protect against psychological conditions like anxiety, panic attacks, and post-traumatic stress disorder (PTSD).
The purpose of the study, published in the open-access journal PLOS One, was to ascertain whether dogs trained on a scent discrimination paradigm could distinguish between samples of human participants’ baseline breath and sweat and samples taken during their participation in an experimentally induced state of psychological threat.
In the latest study, non-smokers who had not recently consumed food or liquids had their breath and sweat samples collected. Samples were taken before and after a demanding math task, along with objective physiological measurements like heart rate (HR), blood pressure, and self-reported stress levels (BP).
Within three hours of being collected, samples from 36 participants who reported feeling more stressed due to the exercise and who also saw an increase in HR and BP throughout the task were presented to trained dogs.
Using a clicker and kibble, four dogs of various breeds and breed combinations were trained to match scents in a discrimination exercise. During testing, dogs were instructed to locate the participant’s relaxed sample, collected just minutes before the task began, and the participant’s stress sample, collected after the task.
Overall, dogs could recognize and act alertly on the sample collected under stress in 675 out of 720 trials, or 93.75 percent of the time, which is significantly more often than would be predicted by chance (p 0.001). The canines accurately alerted the stressed sample 94.44% of the time after being first exposed to a participant’s relaxed and stressed samples. The accuracy of the individual dogs ranged from 90% to 96.88%.
The researchers concluded that dogs were highly accurate at differentiating between baseline and psychologically stressed human breath and sweat samples. These findings imply that trained dogs can detect a VOC profile linked to acute psychological stress. Further research may apply the fact that this odor is perceptible to settings found in the actual world.
The researchers also mentioned the possibility of an odor component serving as a training tool for service dogs tasked with responding to acute stress responses in their owner. More generally, the discovery that dogs can recognize an odor linked to stress offers light on the human-dog bond. It advances our knowledge of how dogs may perceive and respond to human psychological states. Additional research is necessary to determine the precise odor the dogs are sensing, the period during which this odor is perceptible, and any correlations with chronic or protracted stress responses.
Wilson, C., Campbell, K., Petzel, Z., & Reeve, C. (2022). Dogs can discriminate between human baseline and psychological stress condition odours. PLOS ONE, 17(9). https://doi.org/10.1371/journal.pone.0274143
