Specially trained service dogs helped ease PTSD symptoms in U.S. military veterans in a small study that the researchers hope will help expand options for service members.

The U.S. Department of Veterans Affairs provides talk therapy and medications to veterans with post-traumatic stress disorder and runs a pilot program involving service dogs. The VA can prescribe service dogs to certain veterans diagnosed with a visual, hearing or substantial mobility impairment, including eligible veterans with PTSD, and will cover some costs associated with having a service dog.

The agency continues to review the research "to evaluate the effectiveness of service dogs," said VA press secretary Terrence Hayes, "and we are committed to providing high-quality, evidence-based care to all those who served."

Study co-author Maggie O'Haire, of the University of Arizona's veterinary college, said one of the researchers' goals was "to bring evidence behind a practice that appears to be increasingly popular, yet historically did not have the scientific base behind it."

For the study, service dogs were provided by K9s For Warriors, a nonprofit organization that matches trained dogs with veterans during a three-week group class. The dogs are taught to pick up a veteran's physical signs of distress and can interrupt panic attacks and nightmares with a loving nudge.

Researchers compared 81 veterans who received service dogs with 75 veterans on the waiting list for a trained dog. PTSD symptoms were measured by psychology doctoral students who didn't know which veterans had service dogs.

After three months, PTSD symptoms improved in both groups, but the veterans with dogs saw a bigger improvement on average than the veterans on the waiting list. The study, funded by the National Institutes of Health, was published Tuesday in JAMA Network Open.

It wasn't clear from the study whether spending time with any dog would have had the same effect. (About 40% of the veterans in both groups owned pet dogs.) And all the veterans in the study had access to other PTSD treatments.

Service dogs should be considered complementary and not a standalone therapy, O'Haire said.

"When you add it to existing medical practices, it can enhance your experience and reduce your symptoms more," she said.

PTSD is more common among veterans than civilians, the VA says, affecting as many as 29% of Iraq war veterans over their lifetimes. Symptoms include nightmares, flashbacks, numbness or the feeling of being constantly on edge.

"I would wake up in the middle of the night, almost nightly, in a pool of sweat," said Dave Crenshaw, who served with the Army National Guard in Iraq and was diagnosed with PTSD in 2016 while working undercover in law enforcement. Antidepressants helped with some symptoms, he said, but he still felt numb.

The 41-year-old veteran met his service dog, a pointer-black lab mix named Doc, in 2019. He immediately felt what he described as "joy and wholesomeness. It's just an overwhelming feeling of 'Hey, everything's going to be OK.'"

Doc senses when he's upset, often before he notices himself, and come close, Crenshaw said. Today, Crenshaw is no longer taking antidepressants and is enjoying retirement from the military and law enforcement. He gives Doc credit for getting his life back on track.

"It's the greatest medicine with the least amount of side effects," Crenshaw said.