Friends and family petitioned Congress, and a law was finally signed to allow still able dogs to be adopted under unusual circumstances.

Now, Rex lives on a farm in Smethport, Pa., with Dana, who believes the dog wasn't really meant for a soldier's life.

"He loves everybody," she says. "He sleeps beside my bed."

Other dogs in the war zone aren't so lucky. Though no careful count is kept, Army vet Lt. Col. Michael Lagutchik, who supervises care at Lackland, believes about 10 dogs have been killed in Iraq and Afghanistan.

Injuries are common among the dogs. They are cut or scraped, often on their paws. They are bitten by spiders or stung by scorpions. Their eyes and ears are irritated by blowing sand.

The most common injury is probably overheating from the desert sun, which can sometimes spur a dangerous stomach condition called bloat.

Handler Jason Cannon, now a Tennessee state patrolman, knew something was wrong when his dog started to act skittish while searching people crossing into Iraq from Syria. He and his dog were helicoptered back to base, where a vet suspected dehydration and prescribed two weeks of rest for the dog.

"We went out and played ball, pretty much hung out," Cannon says. "Mainly, we didn't do any work at all. 'Vacation' is a good word for it."

Less often, dogs on a mission get shot or bombed. Lackland trainer Trapanger Stephens, who did duty in Iraq, remembers seeing a vet rescue a shot dog with a breathing tube right in the field. The vet did surgery then and there.

Cpl. Megan Leavey and her dog ended up back at Camp Pendleton when another homemade bomb exploded in Ramadi. She got a concussion, and the animal hurt its shoulder. The dog underwent a regimen familiar to athletes: icing, heating, stretching, and motion exercises.

Dogs may wear bulletproof vests or booties to cushion their pads. They sometimes wear doggie goggles — called "doggles" — to keep out blowing sand. However, most handlers have their dogs go natural for fear of overheating.

Regardless of the dangers, the dogs are fearless. For them, checking a road for bombs means a fun walk, their handlers say. "They like what they do," insists Poelaert, who has returned to Exeter, N.H.

These days, he's trying to move beyond memories of the Ramadi explosion, which killed dozens of people, including his best friend, fellow handler Adam Cann.

One image still inspires him, though: the sight of Cann's wounded dog stretched over his body, as if to protect him.