Stress can make people pretty stinky. Humans have two main kinds of sweat glands. The eccrine glands produce sweat that we associate with exercise or warm weather – thin, watery and mostly odorless. We can thank apocrine glands for responding to stress by producing a thick fluid containing fats and proteins that skin bacteria love to digest. The result: stinky compounds somewhat reminiscent of vinegar or leeks.

While humans may find the smell of stress-related sweat somewhat offensive, research has shown that dogs can pick up on our smelly stress cues too. In fact, when exposed to the sweat and breath of humans before or after a stressful math task, the dogs were able to correctly detect the stressed samples between 90-96.88% of the time (Wilson et al., 2022).

New research published in Scientific Reports examined whether the smell of stress in the sweat and on the breath of humans affected a dog’s choices. The researchers hid a bowl behind a screen with 5 possible doors. Only one door revealed a food reward (positive) whereas the opposite end contained an empty food bowl (negative). The three doors in between contained neither bowls nor food (neutral). When the dogs were exposed to the smell of stress, they became less risky and were less likely to approach the doors placed in the negative or neutral locations, and more likely to choose the door leading to a reward. This study suggests that dog trainers and owners may need to consider their own levels of stress when working with dogs as human stress can alter canine learning and decision-making.

Sources:

C Wilson, K Campbell, Z Petzel, C Reeve. Dogs can discriminate between human baseline and psychological stress condition odours. PLOS ONE. 17(9): e0274143, 2022.

Z Parr-Cortes, CT Müller, L Talas, M Mendl, C Guest, NJ Rooney. The odour of an unfamiliar stressed or relaxed person affects dogs’ responses to a cognitive bias test. Scientific Reports. 14(1): 15843, 2024.  

International Hyperhidrosis Society

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Categories: Intelligence and Neuroscience, Pets, Stress

Tags: dog, dog-training, dogs, health, Pets