There has been a growing amount of evidence suggesting service dogs can play a vital role in the recovery of veterans with post-traumatic stress disorder (PTSD), but there are a number of obstacles in the way of getting these helpful animals to the servicemembers who need them most. An increasing number of non-profits and mixed messages from the Department of Veterans Affairs has led to frustration for some vets, according to The Associated Press.

One of the biggest obstacles comes from the VA, which said it will not cover the expenses for services dogs for veterans with traumatic brain injuries until there are more studies proving their effectiveness. Additionally, the VA requires that all service dogs be trained by groups that have been approved by the Assistance Dogs International (ADI) or the International Guide Dog Federation.

Service dogs certainly aren't cheap, and that's why non-profits are so helpful. But they aren't without their problems. Many of them rely on dogs from shelters, and it can be difficult to know how they will react to troops with PTSD. Experts say it's crucial for canines to be bred specifically with the unique training in mind.

"We want to place a dog that makes them more independent, not dependent," Corey Hudson, secretary of ADI, told the AP. "Accreditation is a safeguard."

Despite the considerable anecdotal evidence supporting the idea that troops with PTSD can benefit from service dogs, there have been no double-blind, randomized control trials on whether there is a substantial impact, and a study currently underway could be years away from completion, according to NBC News. Still, there are some who stand by the benefits regardless of the lack of scientific evidence.

"The results are very immediate, they're very quick," Carol Borden, the executive director of Guardian Angels Medical Service Dogs, told NBC. "It's not a cure, but they are able to manage their challenges much better than they have in years."

While widespread use of service dogs may years in the future, the issue shines the spotlight on the importance of addressing PTSD and traumatic brain injuries in the most recent troops. According to Time magazine, about 21 percent of the more than 500,000 troops who have visited the VA post-9/11 have PTSD.