Is there anything a good dog can’t do? New research continues to discover new benefits for cognitive health, stress relief, allergy reduction and more – all to the benefit of the grateful owner of a loyal dog.
Now, a new study has found evidence that our canine companions can identify when someone is experiencing post-traumatic stress disorder (PTSD) just by smell.
Canadian scientists put two skilled and disciplined dogs, Ivy and Callie, through a series of scent-based laboratory tests, finding that both dogs could distinguish between stressed PTSD sweat and regular human sweat with 90 percent accuracy.
The dogs also did well on the isolated samples they couldn’t compare and contrast, with Ivy achieving 74 percent accuracy and Callie achieving 81 percent accuracy.
“Both Ivy and Callie found this work inherently motivating,” said the study’s lead author. ‘Their boundless appetite for delicious treats was also a plus.’
A new study has found evidence that dogs can identify when someone is experiencing post-traumatic stress disorder (PTSD) just by how the person smells. Above, test dog Ivy points to a choice between two options, comparing and contrasting the PTSD-emphasized human scent
The dogs also did it by smelling isolated samples that they couldn’t compare. Above, test dog Callie indicates that the lone sample does not contain any human odors produced by someone dealing with a bout of PTSD.
“It was much harder to convince them to take a break than to get to work,” says lead author Laura Kiirojaa doctoral student in the department of psychology and neuroscience at Canada’s Dalhousie University said in a statement.
“Callie especially made sure there was no hassle.”
Each person produces what the researchers describe as an “odor profile” of volatile organic compounds (VOCs): molecules produced by the human body that evaporate at normal room temperature, including isoprene and monoterpenes.
Before Kiiroja and her colleagues’ new research, it was already known that dogs can detect VOCs in human breath, urine and sweat – and especially in the breath.
These numerous VOCs secreted by the human body can prove to be evidence of traits related to age, diet, genetics, life activities and mood, such as stress level.
But according to Kiiroja, no previous research had looked at whether or not dogs could be trained to detect VOCs associated with episodes of PTSD, whether they come from flashbacks or from milder triggers.
“PTSD service dogs are already trained to help people during times of need,” Kiiroja said. ‘However, dogs are currently trained to respond to behavioral and physical cues.’
“Our research,” she said, “showed that at least some dogs can also detect these episodes through breathing.”
Similar to the police search for truly talented bomb-detection dogs, a search for 25 candidates was conducted to see which dogs could be trained in scent detection.
Ivy and Callie turned out to be the best for the Dalhousie researchers’ work.
The team also recruited 26 human volunteers as “odor donors” for the new study, which was published Thursday in the journal in Limits in allergy.
Each participant came from a different study that examined how people with trauma experience respond to memories of that trauma.
A slight majority of the volunteers in that study, 54 percent, met the diagnostically testable medical definition of PTSD.
These volunteers donated their scents by attending therapy sessions where they were reminded of their past traumatic experiences while breathing into a protective face mask. Those face masks, and masks from their more trauma-free sessions, were then deposited into individual glass storage containers for the later dog experiments.
These volunteers were also asked to complete a survey about their feelings and stress levels.
The team’s experimental PTSD sniffer dogs Ivy and Callie were then trained with both the ‘calm breath’ control face masks and the PTSD stressed test face masks.
The team recruited 26 human volunteers as “fragrance donors” for the new study, which was published Thursday in the journal Frontiers in Allergy. A slight majority of the volunteers in that study, 54 percent, met the diagnostically testable medical definition of PTSD
Above, face masks with relaxed and PTSD-influenced human odors for future testing in the glass sample jars (left) and pieces of those masks in glass vials for active testing (right)
In all tests, scented material was isolated below a depth of 4.7 inches. mouth diameter, stainless steel funnels
The main tests were whether the dogs could detect stress from odors in the wild, without having to choose between two different scents.
The tests were double-blind, meaning that neither the dog nor the person conducting the experiment knew which scents were being used, only another experimenter had that knowledge.
Ivy proved to be about equal at detecting both positive samples (76.19 percent accuracy) and negative samples (71.43 percent accuracy) of everything she was asked to look for.
Callie proved to be much better at identifying negative samples (90.48 percent accuracy) compared to positive samples (71.43 percent accuracy) in these studies.
Most importantly, one of the dogs became good at detecting a specific volunteer’s scene; that knowledge seemed to stay with them from test to test.
“This is a multidisciplinary collaboration between Dr. Sherry Stewart’s clinical psychology laboratory and Dr. Simon Gadbois’ canine olfactory laboratory, both at Dalhousie University,” Kiiroja noted.
‘Neither laboratory could have done this work on its own. We have brought together two different areas of expertise.’
Outside observers expressed interest in further research into the exact chemicals and human hormones produced by people who experience PTSD.
“The study underlines the need for larger-scale research,” the site said Neuroscience news‘(to) investigate the specific hormonal pathways that dogs may respond to in stressed breath samples.’
