People say their goodbyes to Cena a 10-year-old black lab who was a military service dog before they leave for his last ride at the LST 393 in Muskegon, Michigan, on July 26, 2017. (Joel Bissell/Muskegon Chronicle via AP)
U.S. Marine veteran Jeff DeYoung carries Cena a 10-year-old black lab who was a military service dog, aboard the LST 393 where he was put down on July 26, 2017, in Muskegon, Michigan. Cena was diagnosed with an aggressive form of bone cancer after DeYoung noticed he wasn't putting weight on his front left leg. (Joel Bissell /Muskegon Chronicle via AP)
U.S. Marine veteran Jeff DeYoung and Cena a 10-year-old black lab who was a military service dog ride away for his last ride before being put down aboard the LST 393 in downtown Muskegon, Michigan, on July 26, 2017. (Joel Bissell/Muskegon Chronicle via AP)
U.S. Marine veteran Jeff DeYoung and Cena a 10-year-old black lab who was a military service dog ride away for his last ride before being put down aboard the LST 393 in downtown Muskegon, Michigan, on July 26, 2017. (Joel Bissell/Muskegon Chronicle via AP)
Paige Alfred gives a kiss to Cena a 10-year-old black lab who was a military service dog before they leave for his last ride at the LST 393 in downtown Muskegon, Michigan, on July 26, 2017. (Joel Bissell/Muskegon Chronicle via AP)
People say their goodbyes to Cena a 10-year-old black lab who was a military service dog before they leave for his last ride at the LST 393 in Muskegon, Michigan, on July 26, 2017. (Joel Bissell/Muskegon Chronicle via AP)
U.S. Marine veteran Jeff DeYoung carries Cena a 10-year-old black lab who was a military service dog, off the LST 393 where he was put down in downtown Muskegon, Michigan, on Wednesday, July 26, 2017. (Joel Bissell/Muskegon Chronicle via AP)