David Sharpe finally hit bottom on the bedroom floor of his apartment in Yorktown, Va. That’s where he sat, legs folded, ready to finish the fight with the demons that had followed him back from the war zone: the sudden rages; the punched walls; the profanities tossed at anyone who tried to help.

There was little in the room but dirty Air Force uniforms, some empty Jaegermeister bottles and a crushing despair. He took a deep breath. Shut his eyes. Closed his lips a little tighter around the cool steel.

And then something licked his ear. He looked around and locked gazes with a pair of brown eyes.

Cheyenne cocked her head to one side.

“It was just one of those looks dogs give you,” Sharpe recalls. “It was like, ‘What are you doing? Who’s going to take care of me? Who else is going to let me sleep in this bed?’ ”

For a long minute, Sharpe stared into the puzzled face of his 6-month-old pit bull. And then slowly, reluctantly, he backed the barrel of the .45 out of his mouth.

“There’s no doubt about it,” he says now. “I owe her my life.”

This is a different kind of tale of K-9 Corps bravery, distinct from those exploits of grenades sniffed out and warnings barked. Cheyenne’s heroics were in her unconditional devotion. Sharpe, whose series of harrowing encounters as an Air Force security guard in the Middle East led to post-traumatic stress disorder, says that just by being there day after dark day, his dog rescued him from a soldier’s death as surely as if she had dragged him bloody from the battlefield.

A decade later, it’s a much more stout pit bull lolling on the floor of Sharpe’s much neater apartment in Arlington County. But Cheyenne still loves to nuzzle her buddy’s hand whenever she gets the chance. And he still loves to tell the story of how a torn-eared refugee from a shabby animal shelter saved his bacon.

“She was the force that pulled me back into society,” says Sharpe, 32, who was married last month and is now a program analyst in the Office of the Director of National Intelligence.

But it’s also a story of action: Sharpe is trying to give other scruffy pound dogs a chance to save other emotionally wounded warriors. Even as he continues his own recovery from acute depression and PTSD, Sharpe has launched P2V.org (Pets to Vets), a nonprofit group that seeks to link service members and first responders with shelter animals and help them with related expenses and training.

“I couldn’t talk to anybody — not my father, not the counselors — but I could talk to that dog, and she never judged me,” Sharpe says. “We don’t want to hear, ‘Wow, that must have been horrible.’ We just want to talk.”

Sharpe got the idea for P2V after seeing a documentary on the role highly trained service animals can play in a veteran’s recovery. But those elite creatures can take thousands of dollars to prepare and years to deliver. Sharpe saw a more straightforward match to be made between suffering soldiers and animals from the pound.

“Most of the vets I’ve spoken to don’t want dogs to do tricks. We just want companionship,” he says. “Eighteen vets commit suicide every day in this country, and one animal is put to sleep every eight seconds. They can help save each other.”

It costs P2V about $650 for each adoption, including veterinary care, supplies, health insurance and the training consultants the groups make available. So far, P2V has matched 47 animals to vets, many of them former patients at Walter Reed Army Medical Center.

Sharpe has hired his first paid employee and put together an advisory board that features some local heavy hitters, including former White House press secretary Dana Perino and Rep. James P. Moran (D-Va.). They have started volunteer teams in New York and San Diego and hope to expand further.

Jimmy Childers, a Marine sergeant whose left left was lost and right foot injured when a roadside bomb in Afghanistan detonated, was looking for a dog to relieve the dreary monotony of his therapy routine. When a service-dog organization told him that it would be at least 18 months before could he get an animal, he turned to Sharpe. Two weeks later, he was walking, with two canes, through the pens of the Washington Animal Rescue League in the District.

“Tidus isn’t going to be fetching my [prosthetic] leg for me or anything,” Childers says of the beagle that now lives with him and his wife, Brandi, in Gaithersburg. “He’s here to bring joy into my life, and he does that every day.”

He finds himself less prone to outbursts over, in particular, people who illegally park in spaces for the handicapped. “He really calms me down,” he says.

Retired Senior Airman Sharpe says his own descent into the shadowy storms of PTSD stemmed from multiple deployments at bases in Saudi Arabia and Pakistan. One afternoon in a sweltering guard shack, he found himself staring down the rifle barrel of the Saudi soldier manning the post with him. After an intense standoff, Sharpe managed to overpower the man, who turned out to be an al-Qaeda sympathizer.

In Pakistan, he says, he detected and helped subdue two suicide bombers trying to enter a base filled with U.S. military personnel, avoiding the blast only when one of the attackers dropped his detonator.

“They were loaded and ready to rock,” he says. “They were going to blow up the chow hall.”

It was rough duty. There were suicides in his unit, he says. Sharpe was cracking. But he refused any attempt at counseling. He was a mess by the time he got home from his first tour, drinking himself stupid and picking fights in bars. Anything could set him off: snow falling on his arm, a casual word from a stranger.

His visits to family on St. Simons, Ga., were disastrous. When his father, a soft-spoken retired Army Ranger, would try to talk to him, he’d answer with a string of profanities.

“A few months after he left, I found a bunch of holes he’d punched in the walls,” recalls David Sharpe Sr. “He’d moved some picture frames to cover them up.”

One summer day in 2002, a friend asked Sharpe to go with him to an animal shelter in Hampton Roads, where they were stationed. A batch of pit bull puppies had been rescued from a fighting ring.

“I thought, ‘Hell, yeah, I want a fighting dog,’ ” Sharpe said. “I’m a fighter myself.”

There were seven puppies. Only one of them didn’t swarm over Sharpe’s feet, begging for attention. He picked the aloof one, its ears and face already scabbed from an earlier scrap, and named her Cheyenne.

But at his apartment in Yorktown, the hard-drinking fighter started to cuddle his little dog. He started talking to her about things that had happened. She licked his face.

“I felt like a 10,000-pound weight had been lifted off my chest,” Sharpe says.

One night, he awoke from a nightmare and went to the kitchen for a drink. The refrigerator door banged him on the knee and he went nuts, whaling on it, nearly ripping it off the hinges. He heard a little bark.

He snapped “Shut up!” at the dog, but then he scooped her up and took her back to bed.

“She lay on my chest, and I just started sobbing,” he says. “It felt good. She licked my tears, and I had to start laughing.”

It was up and down, and the worst would come a few months later, a stretch of pain and feelings of survivor guilt that would lead him to that dark bedroom with that heavy pistol.

He got better, slowly. When he finally sought professional help, the diagnosis of acute PTSD was nearly instantaneous. He left the Air Force Security Forces in 2005 and began therapy.

“He’s like a different person now,” says his father. “All that stuff was taking over his life. That dog just listened to him for hours.”

In May, Sharpe married Jenny Fritcher, an Air Force staff sergeant stationed at Ramstein Air Base in Germany. She’s about to be discharged and will join her husband, and Cheyenne, in Arlington this fall.

On their afternoon walks along Clarendon Boulevard, Sharpe knows some people are wary of Cheyenne. They see a pit bull and steer clear. Just as some do with angry vets.

“We’re two of a kind,” Sharpe says. “We saved each other.”