Is there anything a good dog can’t do? New research continues to uncover new benefits for cognitive health, stress relief, allergy reduction, and more, all for 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) simply by smell.
Canadian scientists put two skilled and disciplined dogs, Ivy and Callie, through a battery of odor-based laboratory tests, and found that both dogs could differentiate between PTSD-stressed sweat and ordinary human sweat with 90 percent accuracy.
The dogs also did well with isolated samples that didn’t have a chance to compare and contrast: Ivy achieved 74 percent accuracy and Callie 81 percent.
“Both Ivy and Callie found this work inherently motivating,” said the study’s lead author. “His unlimited appetite for delicacies was also a plus.”
A new study has found evidence that dogs can identify when someone is experiencing post-traumatic stress disorder (PTSD) simply by how the person smells. Above, test dog Ivy points, compares and contrasts between a “calm” human sweat and a PTSD-stressed human odor.
The dogs also did well at sniffing isolated samples that they couldn’t compare. Above, test dog Callie points out that the lone sample does not contain the odor she was asked to detect. These tests were “double blind”: neither the dog nor the experimenter in the room knew the answer.
“It was much harder to convince them to take a break than to start working,” says the lead author. Laura Kiirojaa doctoral candidate in the department of psychology and neuroscience at Dalhousie University in Canada said in a statement.
“Callie in particular made sure there was no nonsense.”
Each human being produces what the researchers described as an “odor profile” of volatile organic compounds (VOCs) – molecules produced by the human body that vaporize at normal room temperature, including isoprene and monoterpenes.
Before the new study by Kiiroja and her colleagues, it was already well known that dogs can detect VOCs in human breath, urine and sweat, and especially breath.
These countless VOCs secreted by the human body may 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 study had looked at whether dogs could be trained to detect VOCs related to PTSD episodes, whether flashbacks or milder triggers.
“PTSD service dogs are already trained to help people during episodes of distress,” Kiiroja said. “However, dogs are currently trained to respond to physical and behavioral cues.”
“Our study,” he said, “showed that at least some dogs can also detect these episodes through breathing.”
Much like law enforcement’s search for truly talented bomb-sniffing dogs, a star search of 25 canine candidates was conducted to see which ones could be trained in scent detection.
Ivy and Callie proved to be the best for the job of the Dalhousie researchers.
The team also recruited 26 human volunteers as “scent donors” for the new study, which was published Thursday in the journal. Frontiers in allergy.
Each participant came from another study investigating how people with trauma experience react to reminders of that trauma.
A small majority of the volunteers in that study, 54 percent, met the medical definition of diagnostically verifiable PTSD.
These volunteers donated their scents by attending therapy sessions in which they recalled their past traumatic experiences, while breathing through a protective mask. Those masks, and those from their more trauma-free sessions, were placed in individual glass containers for subsequent dog experiments.
These volunteers were also asked to complete surveys about their feelings and stress level.
Then, the team’s experimental PTSD detection dogs, Ivy and Callie, were trained to remove the “calm breath” control masks and the PTSD stress test masks.
The team recruited 26 human volunteers as “scent donors” for the new study, which was published Thursday in the journal Frontiers in Allergy. A small majority of the volunteers in that study, 54 percent, met the medical definition of diagnostically verifiable PTSD.
Above, face masks containing relaxed and PTSD-influenced human odors for future testing in glass sample vials (left) and pieces of those masks in glass vials for active testing (right)
In all tests, the scented material was isolated to less than 4.7 inches. stainless steel funnels with mouth diameter
But the key tests were whether the dogs could detect stress from odors without having the “multiple choice” option of two different human odors to choose from.
The tests were double-blind, meaning that neither the dog nor the person conducting the experiment knew which odors were being used. Only one other researcher had that knowledge.
Ivy proved to be about equal at detecting positive samples (76.19 percent accuracy) and negative samples (71.43 percent accuracy) of whatever it 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 assays.
Most importantly, however, once either dog became good at detecting a specific volunteer’s scene, that knowledge seemed to stay with them from trial to trial.
“This is a multidisciplinary collaboration between Dr. Sherry Stewart’s clinical psychology lab and Dr. Simon Gadbois’ canine olfaction lab, both at Dalhousie University,” Kiiroja said.
‘None of the laboratories could have done this work alone. “We bring together two different sets of experience.”
Outside observers expressed interest in conducting more studies on what the exact chemicals and human hormones produced by humans experiencing PTSD actually are.
“The study underscores the need for larger-scale research,” according to the site Neuroscience News‘(to) explore the specific hormonal pathways that dogs may be responding to in stressed breath samples.’