Patients often experience dramatic improvement, say service dog experts. They feel renewed confidence in social situations, decrease medication use, and are less likely to startle. Some veterans say it's the only treatment that ever worked so well.

Congress, which required the study in 2009, permitted the VA to match as many as 200 veterans with service dogs. Mark Ballesteros, a spokesperson for the VA, said in a statement to The Atlantic that the study had so far paired 17 dogs with veterans and that the agency is "developing a new plan to carry out this important research." It also notified the Office of Inspector General about the contract violations for further investigation.

Carol Borden, executive director of the vendor under investigation -- Guardian Angels Medical Service Dogs, Inc., in Williston, FL, -- vehemently denied the VA's allegations.

"We were doing this work before and we will continue to do this work because we love our veterans and are passionate about our success and what we are able to give people through our dogs," Borden told me. "We will continue to carry on with anyone who qualifies that wishes to continue with our program."

In a document related to the investigation, officials said they expected the study to resume in 10 months after changes have been made to its design.

In particular, the VA plans to conduct a nationwide search for the best dogs, expanding the number of providers and contracting instead with trainers to pair veterans with an animal. Doing so, the agency hopes, will eliminate a problematic conflict of interest wherein the service dog provider may perceive a financial incentive to pair dogs regardless of whether or not they have received necessary training or would perform well.

Such are the hard lessons of designing a study that is the first of its kind for the VA. But the research has been troubled from the start. It began with three service dog providers, two of which stopped participating earlier this year; it was initially suspended from January to June after a dog bit a young girl. Guardian Angels had no reported incidents when the study resumed.

Brian Jones, a former sergeant major who performed special operations as an Army Ranger and Delta Force soldier, was on the waiting list and said both suspensions were disappointing. He was notified last week by email that VA had canceled its contract with Guardian Angels, advising him to seek the assistance of a mental health provider if the news was upsetting. The email recommended that he not use Guardian Angels, and said that if he received a service dog during the study's suspension, he would be withdrawn from the research.

Jones, who has visited the Guardian Angels facility and said the conditions were pristine, plans to proceed with getting a service dog from Borden. He is scheduled to receive Sarge, a one-year-old German Shepherd, in December, and that thought gives him comfort.