Service dogs for military veterans suffering from post-traumatic stress disorder (PTSD) have grown in popularity in recent years, along with scientific support of their effectiveness. In addition to performing trained behaviors, such as interrupting flashbacks or self-injurious actions, service dogs can also provide strong social and emotional support when needed.
The ability that dogs have to sense when their companion is upset has been speculated upon for many years, but only recently have scientists begun to understand how they do this. In a novel study, researchers at Dalhousie University revealed that dogs may be able to detect the stress-related volatile organic compounds (VOCs) from people with traumatic histories, which has the potential to improve how service dogs for people with PTSD are trained in the future.
Twenty-six donors were recruited from a study into the mechanisms underlying trauma, 54% of which had a likely diagnosis of PTSD. Their breath was captured when they were calm as well as stressed, after being exposed to a trauma cue. These samples were then presented to two scent detection dogs in a discrimination and detection task.
The discrimination task investigated whether the dogs could discriminate between the calm and stressed breath samples of the same person. Whereas the detection task assessed their ability to identify the stressed sample of multiple people, or the same person after exposure to different stressors, without using the calm sample for reference.
The results revealed that dogs’ accuracy during the discrimination task was close to 90%, demonstrating that they were able to identify the stress-specific VOCs of individuals. However, their performance was slightly lower in the detection task, with 74% and 81% accuracy, suggesting that generalising the stress markers between different people and situations was more difficult.
It is not known for certain which VOCs dogs used to perform the tasks, but the researchers suggest that they were distinct endocrine stress markers. By comparing the dogs’ accuracy to participants’ self-reported emotional responses to trauma cues, it became apparent that one dog’s performance was related to participants’ fear responses, whilst the other was related to shame responses.
This study is the first to show that some dogs can detect the VOCs that it is believed that people with histories of trauma emit when triggered. This finding is supported by other recent research revealing that dogs can detect and respond to human stress odors. It also raises the possibility that dogs are sensitive to different types of stress signals which could potentially be incorporated into the training of service dogs for people with PTSD.
Currently, service dogs are trained to respond to the physical symptoms of PTSD, such as hyperventilation. However, if dogs are able to detect the VOCs associated with PTSD distress, they could be trained to alert their partner before an episode occurs, giving them the opportunity to use techniques that prevent escalation. This intervention could be life changing for the millions of people worldwide that suffer from PTSD, but first more research is needed to validate these results.
Further scientific investigation should endeavour to isolate the specific endocrine stress markers that dogs can detect in VOCs, by varying the concentrations of different hormones. Also, for dogs to be able to alert their partners with PTSD to an oncoming episode, confirmation is needed that dogs can detect these markers in the early stages of stress, including in very low concentrations. If so, it would be worthwhile to establish whether training dogs to discriminate their human partner’s personal VOCs can boosts their performance.
Future research should also expand the type of donor used in future experiments to determine how dogs respond to different stress cues. This could be achieved by including participants with and without histories of trauma, to reveal whether dogs can identify endocrine stress markers specific to trauma, or stress more generally. And finally, individuals with different types and levels of stress could be assessed, such as people with autism or social anxiety, to provide a more comprehensive understanding of dogs’ abilities to detect stress-specific VOCs and potential applications.
This study represents a novel investigation into dogs’ ability to detect stress-related VOCs. The findings, although preliminary, open up a new avenue of enquiry for the advancement of service dog training. The possibility to provide an early stress alert for sufferers with conditions such as PTSD could be revolutionary, providing them with the opportunity to intervene early to prevent escalation and live more independent lives. However, there is much that is currently unknown, and extensive further research is needed to start filling in these gaps.
Article by Dr. Carla J Hart: https://linktr.ee/carlajadehart