Credit: schumer.senate.gov

Sergeant Rex, the bomb-sniffing dog who served three combat tours in Iraq, has finally been reunited with his former handler.

Sgt. Rex served almost 11 years as a military working dog and is trained to sniff out nine different explosive materials. Today, Sgt. Rex retired, and was returned to his old handler, marine corporal Megan Leavey.

"I haven't seen him in so long, so, it's nice to see him again," said Leavey, according to ABC News San Diego affiliate 10 News.

Leavey and Sgt. Rex were injured in Iraq during a bomb blast in 2006.

"I was on foot patrol in Iraq during the day, there were insurgents watching us from afar and they detonated an IED at a certain point when we got close.  It was real scary, it was a long day for us, we got through it together and recovered together after," said Leavey.

The injury brought an end to Leavey's career, and she returned to New York, where she tried unsuccessfully to adopt Sgt. Rex.

The military denied Leavey's request because they thought Sgt. Rex would be able to continue his bomb-sniffing duties once he recovered from his injuries.

Leavey began a new adoption effort earlier this year when she learned that Sgt. Rex was about to be retired. She launched a high-profile campaign to adopt him. She had received support from veterans groups and New York Sen. Charles Schumer, who started a petition on her behalf called "Saving Sgt. Rex." Almost 22,000 people signed the petition.

"I'm just glad that we're both together now and this is able to happen," said Leavey.

Like all retiring military dogs, Sgt. Rex was assessed in his temperament and physical ability to get back to civilian life before being adopted. Dogs are returned to their handlers about 65 percent of the time.

Sgt. Rex's first handler, Mike Dowling, wrote a book called Sergeant Rex: The Unbreakable Bond Between a Marine and His Military Working Dog about his experience with the dog on their first tour to Iraq.

Dowling says Leavey and Sgt. Rex are a perfect match.

"He's a combat-wounded marine, and someone that's going to understand him the best is another combat-wounded marine," said Dowling.

"He's my partner, and we just developed such a strong bond with each other. This is what he deserves," said Leavey.

ABC News affiliate 10 News contributed to this report.