An upstate New York Marine is on a mission to save the dog that served alongside her in Iraq.

Marine Corporal Megan Leavey of Rockland County, NY, is desperately trying to adopt Sergeant Rex, a German Shepherd military working dog. When Leavey served two tours in Iraq, the two were a team tasked with identifying and disabling roadside bombs.

In 2006, both Leavey and Rex were injured by an explosive. She was discharged with a Purple Heart, but Rex recovered from his wounds and continued to serve. Now that Rex is 10 years old and is in declining health, Leavey, who has fully recovered from her injuries, wants him to live out his remaining dog years with her.

But the clock is ticking.

In order for working dogs to be adopted, they must be thoroughly vetted by the military to determine if they’re a danger to the public, Air Force spokesman Gerry Proctor said.

Because Rex was a patrol dog, he had to undergo a videotaped “bite test” that will be reviewed by an animal behaviorist who will make a final recommendation. As part of the test, the dog is introduced to an ordinary circumstance — such as meeting another dog — to see how he responds. Some dogs are put down after they serve because they are deemed too dangerous, Proctor said.

“They should know the results within the next day or so,” Proctor said.

A soldier’s best friend

Military dogs are invaluable in the field, Air Force spokesman Gerry Proctor said.

“They are the tip of the spear in the war on terror,” said Proctor. “They can do things that no human or machine can even come close to doing.”

But beyond their military uses, some say the bond between a soldier and his dog is very strong.

“These animals are soldiers. No one in America would expect a soldier to leave another soldier behind,” said Barbara Teasdale, 60, of San Francisco, founder of Vets Adopt Pets, an organization that works to unite veterans and animals.

The life of a military dog

The military breeds about 120 puppies each year and there are currently 2,700 dogs serving alongside U.S. troops worldwide, Air Force spokesman Gerry Proctor said. Half the animals are German Shepherds, 25 percent are Belgian Malinois and the other 25 percent are sporting breeds like labs and mutts.

The dogs are then trained for the following tasks:

Patrol dog: these dogs are trained for four months to attack and detect narcotics or explosives. Rex is a patrol dog.

Specialized search dog: these dogs are trained for 95 days to works off-leash from their handlers and are trained to sniff out IEDs.

Combat tracker dog: these Marine Corps dogs are trained for 45 days to track humans, like enemy insurgents.

Last year, more than 320 working military dogs were put up for adoption and around 8 were put to sleep via a chemical injection, Proctor said.

Follow Emily Anne Epstein on Twitter @EmilyAEpstein.