Courtesy Logan Black

Former Sgt. Logan Black and his bomb-sniffing dog, Diego, are pictured in April 2006. The pair swept for improvised explosive devices and other weapons in Iraq. Black, who has post-traumatic stress disorder, is campaigning to adopt Diego.

Logan Black has only one dream about his time in Iraq.

From 2006 to 2007, the former sergeant was deployed in Fallujah, sweeping for improvised explosive devices (IED), ammunition, firearms, grenades and raw bomb materials. He survived firefights and IED attacks.

What Black dreams about, though, is the yellow Labrador -- Diego -- that searched for weapons alongside him. 

Black, 34, began training with Diego at Fort Leonard Wood in Missouri when the dog was a year old. He parted with Diego upon leaving the Army in May 2007. Black has wondered about Diego's fate ever since, leaving phone messages with his unit every six months or so with updated contact information, but said he never heard back.

"I figured he had to be in Afghanistan or Iraq the majority of the time after I left," Black said. "[Diego's safety] was always a concern, but I tried to push that out of my mind. I hoped that he had a handler that kept him safe."

Related: Marine and dog bonded by war, divided by red tape

Black recently turned to a website about military working dog adoptions and posted a request for help to find Diego. He received a response from someone who said he was Diego's second handler. The dog, he said, had been sent back to the U.S. from Iraq in 2008 after another yearlong deployment. 

Determined to reunite with Diego, Black recently started a Facebook and Twitter campaign to locate and adopt the dog. On Monday, he learned that Diego, now 8, is stationed at Lackland Air Force Base in San Antonio as a demonstration aide, teaching other soldiers how to be handlers.

Courtesy Logan Black

Black and Diego, in November 2006, sit in front of a memorial for a former handler and his dog, both of whom were killed in action.

"The greatest thing about this is now I know where he is," said Black, who wants to expedite Diego's adoption.

What many veterans don't know, said Collen McGee, a spokeswoman for the 37th Training Wing at Lackland Air Force Base, is that a prior handler has priority in adopting his or her retiring dog if it is not first assigned to a civilian law enforcement agency.

Those unaware of the adoption process often go to great lengths to reunite with their dogs. McGee said she receives about one Congressional request a month to help a veteran handler adopt a dog. In addition to starting an online campaign, Black took the same approach and reached out to Sen. Claire McCaskill, D-Mo., and Sen. Roy Blunt, R-Mo., for assistance. Last year, 319 military working dogs from across the services were adopted; about 90 percent of dogs are adopted by their former handlers.

Technical Sergeant Joseph Null, who runs the adoption program for the 341st Training Squadron at Lackland, told msnbc.com that Diego is nearing retirement age, but in the meantime continues to perform a vital role.

"Without dogs like Diego, there would be no military working dog program," he said. "He’s a critical asset to developing future dog handlers."

Black hopes to train Diego as a service dog to help manage post-traumatic stress disorder -- specifically to help calm him down during stressful situations.

His symptoms emerged after returning home to Salt Lake City. That is when the dreams about Diego began, and when he started to notice a hyper-sensitivity to smells and sights that reminded him of Iraq.

Rip Black, Logan's father, said that much of his son's concern around his deployment was for Diego's safety. "This young man and this dog had a bond that very few of us will ever know or understand," he said.

Black worried that Diego had developed PTSD after an IED struck the back of a vehicle the pair was riding in April 2006. Diego leaped from the back seat into Black's lap and shook uncontrollably.

"After that attack, any kind of loud noises would send him into a similar state," said Black. Those noises included base artillery, gun fire and helicopters. Black would calm him down by bringing out Diego's favorite toy, a hard rubber cone. "We were always able to work through it so it never really slowed him down."

Null said that while Diego had been sensitive to loud noises and was eventually de-certified as a specialized search dog, he was never diagnosed with PTSD.

Null is helping Black through the adoption process, but said there is no timeline yet for Diego's retirement.

Black said he will continue campaigning to be reunited with his friend: "Diego has been the biggest wish I've had for a very long time."

Rebecca Ruiz is a reporter at msnbc.com. Follow her on Twitter here.

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