A pet is special no matter what, but for Marine veteran Lance Cpl. Jeff DeYoung of Muskegon, Michigan, his black Lab, Cena, is much more than just a dog.

Back in 2009, DeYoung was deployed to Afghanistan and during his tour he was paired up with Cena, whose job was to detect explosives and keep the troops safe.

Cena was "trained to detect more than 300 different types of explosives, and if he smelled something interesting on patrol, he would lie down and notify me, and then I'd call in an explosives technician," DeYoung wrote in a post on BBC. This responsibility meant the two "had to trust each other" because "any mistake could have been fatal."

So as you can only imagine, it didn't take long for the pair to develop a tight bond. They were so inseparable that they became known among their comrades as "Kid and Chicken."

DeYoung's time in the war zone came to an end, but Cena had to embark on two more tours with different handlers which meant that the veteran and his furry sidekick didn't see each other for the next four years.

To put a "Band-Aid over Afghanistan," DeYoung got married and started a family, but through it all he suffered from PTSD.

Luckily, a few years later in 2014, he reunited with Cena and adopted him as a service dog. This was exactly what the former Marine needed to help him through his rough patch. Raising his children became easier and he was able to enjoy life again.

"By the time my third daughter was born, I was able to do a lot of the diaper changes and bottle feeding even if she was crying," DeYoung recalled. "And to finally be able to help my daughter felt like being released from jail, it was freedom."

Unfortunately, Cena was recently diagnosed with terminal bone cancer. DeYoung wanted to make sure that his best friend enjoyed the last of his days before the "trip upstairs" so he created a bucket list with the help of his friend Jacobie Baumann.

They started a GoFundMe page so they can raise funds for Cena's bucket list, which includes stuffing his face with awesome food and sticking his head out of a Jeep with a top down.

Baumann wrote, "This money will go towards awesome food that [Cena] can stuff his face into...vet bills, a statue or a beautiful head stone that he deserves, rent[ing] a jeep that has a top down so he can stick his head out and catch some wind before his trip upstairs."

The pair raised $31,000 out of their $40K goal and Cena was able to enjoy his remaining time, but unfortunately he had to be put down soon after.

Click on the next page to see the bittersweet hero's goodbye Cena received.

Cena's time came to an end earlier this week, but it wasn't without a celebration of his heroic life.

A beautiful ceremony organized by the U.S. Marine Corps League was held in honor of the beloved canine at the USS LST 393 Museum in downtown Muskegon.

The loyal dog doned a homemade Marine uniform and "Taps" was played as he was carried out in a wagon. Following the ceremony, an immobile Cena was transported to Lakeshore Animal Hospital where he took his last breath.

DeYoung shared a heartbreaking post on Facebook mourning his companion:

The GoFundMe page was also updated to inform donors that remaining money will be used to pay for the dog's headstone.

"I know Cena had plenty of car rides, ate some awesome food, but that money was pulled from other places," he said. "People have reached out and said they will help with the headstone, and I know there are a few marines trying to fly in from all over the world."

"Our brotherhood is a bond that should never be forgotten, and we plan on preserving the memories of Cena so our future families will truly understand the love between [us and] man's and woman's best friend," Baumann said.

Our thoughts are with DeYoung and his family during this difficult time. Rest peacefully, Cena.