Service Dogs May Lower Stress Levels of Veterans With PTSD

June 20, 2018
Kerry Lengyel

Can service dogs help military veterans face their current battles with post-traumatic stress disorder?

Studies have shown that pets can help alleviate the symptoms of post-traumatic stress disorder (PTSD) because these victims may find being around animals easier than being around people. But none of these studies have been able to define the biobehavioral effects of service dogs on veterans with PTSD.

A new study, co-funded by the Human Animal Bond Research Institute (HABRI) and Bayer Animal Health, is now the first published research of its kind to do just that. Findings were recently published in the journal Psychoneuroendocrinology.


A research team from the Purdue University College of Veterinary Medicine in West Lafayette, Indiana worked alongside K9s For Warriors—a nonprofit that provides veterans with service dogs—to quantify how service dogs may affect the mental health and well-being of veterans.


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“Our previous research suggests that the presence of a service dog reduced clinical PTSD symptoms and improved quality of life,” Maggie O’Haire, PhD, assistant professor of human-animal interaction at Purdue CVM and lead of the study, said. “In this study, we wanted to determine if those beneficial effects also included changes in the physiology of stress."

For the study, investigators compared a group of post-9/11 military veterans with PTSD who had a service dog (n = 45) to a group of post-9/11 military veterans with PTSD on the waitlist to receive a service dog (n = 28).

The investigators decided to focus on cortisol—a biomarker involved in the stress response system—which can easily be measured through a person’s saliva. According to previous research, healthy adults without PTSD experience an increase in cortisol after waking up.

Saliva samples were collected from both groups of veterans on 2 consecutive weekday mornings at awakening and 30 then minutes later to quantify the cortisol awakening response (CAR).

In addition to saliva samples, veterans also answered survey questions to measure levels of anxiety, anger, sleep quality and disturbance, and alcohol abuse.

Research Findings

The investigators found that military veterans suffering from PTSD who had service dogs produced more cortisol in the morning than those without a service dog.

"This pattern is closer to the cortisol profile expected in healthy adults without PTSD,” Kerri Rodriguez, a human-animal interaction graduate student at Purdue CVM and the other study lead, said.

Having a service dog was also associated with less anger, less anxiety, better sleep, and less alcohol abuse.

These results indicated that the placement of a PTSD service dog “may have a significant positive influence on both physiological and psychosocial indicators of well-being in military veterans with PTSD.”

Future Research

While these findings are positive, they did not establish a direct correlation between cortisol levels and levels of PTSD symptoms on an individual level. This means that further studies are needed—and those next steps are already underway.

The investigators are now working with the National Institutes of Health to conduct a large-scale clinical trial where veterans diagnosed with PTSD, with and without service dogs, are studied over an extended period of time. This will allow the research team to look at CAR before and after these veterans acquire their service dogs.

"The longitudinal nature of this clinical trial should bring about a better understanding of the interrelationships between physiological and behavioral processes, PTSD symptoms, and service dogs,” Dr. O’Haire said.