Dogs smell your stress
Given that dogs have a keen sense of smell and their close domestication history with humans, researchers wanted to see if dogs could smell when humans are stressed. To test this they collected samples of breath and sweat from non-smokers before and after a fast-paced arithmetic test. As well as self-reported stress levels, heart rate and blood pressure were measured. Samples from those who showed stress at the task were shown to trained dogs within three hours of being collected. Dogs of four different breeds were used and asked by trainers to find a subject’s stress sample (taken at the end of the task) while the same person’s relaxed sample (taken before the task) was also in the line-up. Overall, dogs were correct in selecting the stress sample 93.75 per cent of the time, suggesting they can detect the change in compounds produced by humans during stress. Source: PLOS One