How dogs can be used to detect PTSD: Scientists train pups to sniff out an oncoming flashback by smelling your breath

Their sensitive noses can detect an impending seizure, sniff out signs of Covid and even expose cancer.

Now, scientists have successfully trained two dogs to smell trauma from a person’s breath.

The researchers trained 25 dogs to sniff out the chemical signs of stress in someone’s breath. 

However, only two were skilled and motivated enough to complete the study – Ivy, a Red Golden Retriever, and Callie, a German Shepherd and Belgian Malinois mix.

In the future the scientists think these talented pooches might be able to identify when someone is about to have a frightening flashback.

PTSD arises from exposure to a traumatic event and can lead to debilitating symptoms that include re-experiencing the event in the form of a flashback.

Currently, service dogs are used to help patients with PTSD by alerting and interrupting when their companions are struggling with their symptoms.

By training dogs to recognise the signs of an episode from the breath alone, the scientists hope that service dogs can intervene earlier and keep their companions safe.

Researchers from Dalhousie University, in Canada, recruited 26 people who had been through some kind of trauma as scent donors for their study.

Half of the participants had been diagnosed with post-traumatic stress disorder (PTSD), a mental health condition that is triggered by a terrifying event. 

To donate scents, the participants attended sessions where they were reminded of their trauma experiences while wearing different facemasks.

One facemask provided a calm breath sample, while the other provided a ‘target’ breath sample which was worn while they recalled their ordeal.

In the meantime, the scientists recruited 25 pet dogs to train in scent detection.

Both were trained to recognise the ‘target’ odour and were presented with a series of samples to see if they could accurately detect the stress scents.

All humans have a ‘scent profile made up of volatile organic compounds (VOCs) which are determined by our genetics, age, and other variables.

Previous studies have suggested that dogs may be able to smell VOCs associated with human stress.

Scientists from Queen’s University Belfast trained dogs to detect stress in sweat and breath with an accuracy of 93.75 per cent.

However, this is the first study to show that dogs can also sniff out the chemical signatures associated with PTSD.  

First author Laura Kiroja says: ‘Both Ivy and Callie found this work inherently motivating, their limitless appetite for delicious treats was also an asset. 

‘In fact, it was much harder to convince them to take a break than to commence work.’

During testing with donated facemasks, both dogs could discriminate between stressed and non-stressed samples with 90 per cent accuracy.  

And, in tests with pure VOC samples, Ivy achieved 74 per cent accuracy and Callie achieved 81 per cent accuracy.

Ms Kiiroja said: ‘PTSD service dogs are already trained to assist people during episodes of distress.

‘However, dogs are currently trained to respond to behavioural and physical cues. Our study showed that at least some dogs can also detect these episodes via breath.’

Further analysis revealed that Ivy was more likely to identify participants who were feeling particularly anxious, while Callie was more likely to identify when people were feeling shame.

‘Although both dogs performed at very high accuracy, they seemed to have a slightly different idea of what they considered a ‘stressed” breath sample,’ Ms Kiiroja said.

‘We speculated that Ivy was attuned to sympathetic-adreno-medullar axis hormones, like adrenaline, and Callie was oriented to the hypothalamo-pituitary-adrenal axis hormones, like cortisol.’

The researchers said their findings, published in the journal Frontiers in Allergy, could one day lead to trained dogs potentially interrupting PTSD episodes at an earlier stage, making their interventions more effective.