Dogs are well known for their sense of smell. Their olfactory senses have many uses in the military and medicine. Some well-established dog smell facts are that when trained, they can sniff out bombs, bodies, and illegal drugs as part of their military routine. They also play a huge role in assisting the blind, elderly and other people with mobility problems. 

Therapy dogs are known to be friendly and calm to better the lives of patients and the elderly in settings such as schools, hospitals, and nursing homes. This ability of dogs to psychologically understand humans has opened the door to more research, and much has been discovered on how dogs process smell. One such recent study has found out how can dogs help with stress in people.

Stress hormones in humans

Human odors contain chemicals in them that convey messages. They are collectively known as chemosignals and differ based on the situations we face. Dogs have been domesticated long enough with humans to pick up on these odors. This is why we see dogs play a huge role in supporting humans with psychological conditions such as anxiety, panic attacks, and post-traumatic stress disorder (PTSD). This is so popular that, in some instances, the waiting list for PTSD service dogs has grown from months to years. 

Can dogs smell stress hormones?

It is well established that dogs can smell our chemosignals and help keep us calm during anxiety, panic, and PTSD attacks. More studies are being done to find out how dog’s ability to smell helps in medicine and which other psychological ailments they can detect. One such is a recent study conducted by researchers at Queen’s University Belfast which has concluded that dogs can smell and find out when humans are stressed.  

The study

Breath and smell samples were collected from the 36 participants involved in the study. The samples were collected under two circumstances: baseline (when normal) and after a stress-inducing task. These samples were then placed before 4 dogs – Treo, Fingal, Soot, and Winnie to detect. The dogs were trained in advance to detect stress-related odors.


The dogs were able to correctly detect the samples which contained stress-related odors. Furthermore, the findings established the fact that there is a detectable odor associated with acute negative stress in humans. Due to this odor difference, even untrained dogs may be able to sniff and find out negative stress in humans. 

Findings from studies like this can further be applied to the training of anxiety and PTSD service dogs. Currently, dogs are predominantly trained to respond to visual cues. Knowing that there is a detectable odor to stress may raise discussion about the value of olfactory-based training in dogs.

We have learned that our pets can smell more than just the food on our floor and how dog’s ability to smell helps in medicine. So the next time your pet pooch comes and comforts you know that it is their 220 million olfactory receptors detecting that you are stressed.