NYPD Transit Crime Unit Officer Juan Rodriguez with Cezar. (Angel Canales / ABC News)

Growing up on a military base, NYPD Transit Crime Unit Officer Juan Rodriguez always looked up to his father, a sergeant major with U.S. Army Special Forces. "That's what I saw at a young age. It was something I always wanted to do," Rodriguez says.

So he followed in his father's footsteps and joined the Army in 1993, serving as an Army Ranger in the 7 th Infantry Division at Joint Base Lewis-McChord in Fort Lewis, Wash.

During his time in the Army, Rodriguez was deployed once to Guantanamo Bay, Cuba, for a humanitarian mission and later to Saudi Arabia after the Khobar Towers bombing in 1996. "I had a great time in the Army and accomplished all my goals," he says.

U.S. Army Vet and NYPD Transit Crime Unit Officer Juan Rodriguez in the Army. (Juan Rodriguez)

Rodriguez left the Army in 1997, moved to New York City and two years later started working for the New York City Police Department.

His transition to civilian life was pretty smooth, he says. "The camaraderie between the cops when you go to work, some of them former military, is very similar to the Army," he says. "There is a strong bond between the people we work with. Everybody looks out for each other. They'll do whatever they can for the guy next to you."

U.S. Army Vet and NYPD Transit Crime Unit Officer Juan Rodriguez

Rodriguez spent the majority of his NYPD career as an officer at the 48 th Precinct in the Bronx.

While Rodriguez loved the Army from an early age, he also loved pets. He grew up with dogs and always wanted to work with them professionally one day. "I think there's no better partner. No better loyalty than having a K-9 by your side," he says.

Rodriguez got his wish when he joined the NYPD Transit K-9 Unit. He's now the handler of Cezar, a 4-year-old German shepherd who also served in the military. Cezar is the first military dog to be adopted by the NYPD since the Transit K-9 unit launched in 2006.

Cezar with former retired Army vet handler Brian Connelly

The NYPD does plenty of coordination with other agencies all across the country. "I heard about a program that the U.S. Army runs where they bring the dogs back from deployment," says Randy Brenner, training supervisor with the NYPD Transit K-9 Crime unit.

The NYPD tested 50 dogs for the job before they decided to add Cezar. Law enforcement agencies are encouraged to adopt retired military dogs that still have a working life. "He's already trained and tested and now we can use it in the police department," says Brenner, who is training Rodriguez.

From left to right. Officer Brenner, Rodriguez and Rotschild from the NYPD Transit Crime Unit. (Angel Canales / ABC News)

The K-9 unit uses three breeds - German shepherds, Belgian shepherds (the Malinois) and Labradors - for various functions.

Both Rodriguez and Cezar are training at the same time for the job and Rodriguez says he loves everything about Cezar. "He's loyal. We bonded right away. He loves my son. I take him home. I can't walk him without my son," Rodriguez says, referring to 2-year-old son Hunter.

"Hunter always says to me, 'It's Hunter's dog, right?' and I say, 'Yes, is Hunter's dog.' We go outside and he'll run up and down the driveway," Rodriguez adds. "It is fun to see them play and to know that my son is going to grow up with him."

Cezar was deployed oversees three times and retired in 2012 from the military. He once saved a Navy SEALs squad when he detected two bombs. "I'm very excited to be here," Rodriguez says of the new assignment. "The whole transit system is new to me. Cezar and I will be training and learning and working in the train system."

From left to right. Officer Rotschild, Rodriguez and Brenner from the NYPD Transit Crime Unit in Times Square. (Angel Canales / ABC News)

Depending on the discipline, the amount of time a dogs needs training varies. Scent detection takes about 12 weeks. Patrol capacity is about 16 weeks.

"I think he's more of a veteran than I am," Rodriguez says. "He's had three deployments. I only had two. It is an honor to work with him. It sounds funny to say that I'm honored to work with a dog but I know I can trust him and I feel comfortable knowing that if I go out there, he'll find anything and help save lives."

For Rodriguez, it's great to finally be able to be working for a dog. "I feel like I'm a kid again. It brought back my military time," he says. "I'm not sure how long their working life is but I hope he lasts a good amount of years so I can work with him as long as I can.

"Just like anybody who has a pet, you grow a bond. He's not only your pet at home but your partner at work."

Second Tour is an ABC News digital series profiling the lives of military veterans who are doing unique things in the civilian world. For more stories, click here.

ABC News video editor Arthur Niemynski contributed to this report.