A dog runs toward a man outside.
Research suggests that a service dog reduces clinical PTSD symptoms and improves quality of life. (For Spectrum Health Beat)

Service dogs may help reduce levels of the stress hormone cortisol in military veterans who have post-traumatic stress disorder, a new study finds.

For the study, researchers compared a group of veterans with PTSD who had a service dog to a group of veterans on the waitlist to receive one.

“Our previous research suggests that the presence of a service dog reduced clinical PTSD symptoms and improved quality of life,” said study co-leader Maggie O’Haire. She is an assistant professor of human-animal interaction at Purdue University’s College of Veterinary Medicine, in West Lafayette, Ind.


Our Take

Benefits of owning a dog:

  • Fight heart disease. Owning a dog has a positive impact on blood pressure, which is one of the main factors in heart attack and stroke, according to Thomas Boyden, MD, MS, Spectrum Health program director of preventive cardiology. The American Heart Association reports a link between pet ownership and lower cholesterol and triglyceride levels. Studies also show you’ll be more likely to survive a heart attack if you have a dog.
  • Relieve stress. “Being around pets, and dogs in particular, actually changes your body at a hormonal level,” said psychologist Jared Skillings, PhD. Of course, it’s not a cure-all. “Getting a dog won’t cure depression or clinical anxiety, but it certainly can help.”
  • Reduce loneliness. Dogs provide unconditional love. They’re caring, excited to see you and glad to be by your side. Need to talk? “Dogs are good listeners and they’re not going to argue with you,” Dr. Skillings said.
  • Improve sociability. There’s also the added benefit of the camaraderie among dog owners. “Having a dog can connect people to other pet owners, which can reduce isolation, too,” Dr. Skillings said.
  • Inspire exercise. A study published in the journal BMC Public Health said the average dog owner walks 22 minutes more per day than those who don’t own a dog. Daily walks have lots of added benefits, from controlling chronic conditions to burning weight and improving moods.
  • Add purpose. Having a dog or any other pet can give you a reason to get going in the morning. Size doesn’t matter. In fact, cats, horses and birds can all have a similar effect. Even tiny pets—hamsters, mice, fish, insects—can imbue you with a sense of purpose. In one study, elderly people were asked to care for a cage of five crickets. After eight weeks, the people who had the crickets in their homes were less depressed and had better cognitive function than those in the control group.

“In this study, we wanted to determine if those beneficial effects also included changes in the physiology of stress,” O’Haire said in a university news release.

The researchers focused on cortisol, a biomarker involved in the stress response system, and one that is detected through saliva.

According to study co-leader Kerri Rodriguez, “military veterans with a service dog in the home produced more cortisol in the mornings than those on the wait list.”

Rodriguez explained that “this pattern is closer to the cortisol profile expected in healthy adults without PTSD.”

In addition, “having a service dog was also associated with less anger, less anxiety and better sleep,” she noted. Rodriguez is a human-animal interaction graduate student.

The findings are the first of their kind and offer insight into how service dogs may provide mental health benefits to veterans with PTSD, according to the study authors.

The researchers are now conducting a large-scale, long-term U.S. National Institutes of Health clinical trial comparing veterans with service dogs to those without.

The report was published in the journal Psychoneuroendocrinology.