Dogs have been trained to detect trauma stress by smelling humans’ breath.

In an intriguing pilot study, scientists have trained dogs to recognise stress cues on humans’ breath, in the hope of increasing the effectiveness of PTSD assistance dogs. 

This novel approach could enable dogs to alert and assist their companions earlier, even before the individuals are aware of an impending traumatic episode, enhancing the efficacy of interventions.

Using their extraordinary sense of smell, dogs have been trained to identify early signs of various medical conditions, including seizures and hypoglycemic episodes. 

Extending this capability, a recent study has demonstrated that dogs can also be taught to detect oncoming PTSD flashbacks, based on the scent of human breath after recalling traumatic experiences.

“PTSD service dogs are already trained to assist people during episodes of distress. Our study showed that at least some dogs can also detect these episodes via breath,” said Laura Kiiroja of Dalhousie University, the study's lead author.

PTSD manifests through symptoms such as re-experiencing traumatic events and hyperarousal. Dogs assisting PTSD patients typically respond to behavioural cues. 

The new finding that dogs can discern stress markers in breath opens up possibilities for more timely and effective interventions.

Humans emit volatile organic compounds (VOCs) which can be influenced by stress. 

The study, a collaborative effort between Dalhousie University’s clinical psychology and canine olfaction labs, trained two dogs, Ivy and Callie, to identify stressed breath samples with high accuracy.

The researchers worked with 26 human participants, who provided breath samples during trauma recollection sessions.

Meanwhile, 25 pet dogs were initially recruited for training in scent detection, but only Ivy and Callie completed the training, demonstrating a remarkable 90 per cent accuracy in identifying stressed samples.

The dogs' successful identification correlated with the participants' self-reported emotions, suggesting a nuanced understanding of stress markers. 

This distinction could be crucial in tailoring PTSD service dogs' training for alerting to early-onset symptoms, potentially involving different hormonal cues.

Plans are underway to expand the research to confirm the involvement of specific stress-related hormonal pathways and to establish the reliability of dogs detecting stress VOCs across varied contexts.

More details are accessible here.