TAMPA — Lying in the back of Tampa police Officer Ryan Flannigan's police car, Chesney heard the sirens and jumped up as if he was ready to go to work.

The nearly 10-year-old German Shepherd couldn't have known that the sirens were for him, a police escort to the vet's office. Riding with him in the car, Flannigan's wife Kristin was shocked by the dog's jump to attention. She told her husband that maybe this trip wasn't necessary after all, that Chesney had more time.

But Ryan Flannigan, Chesney's partner of eight years, knew his dog was suffering.

"That's just the special quality these dogs have," he said. They're ready to fight to the very end."

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Flannigan, 38, knew from the start of his career that he wanted to be a K-9 officer.

The officers and dogs were often on the priority calls, chasing suspects. And Flannigan grew up with dogs and had his own at home.

He joined the department's K-9 unit in 2010. Chesney was his first dog, named after one of Flannigan's favorite musicians, Kenny Chesney. And as police dogs and their owner/handlers do, they became inseparable.

"We truly spend more time with that dog than with our family or anyone else," he said. "We go to work with them for 11 hours a day and they come home with us."

For more than eight years, they chased fleeing suspects together and sniffed for explosives at Bucs games, concerts and other big events. Flannigan estimates Chesney had hundreds of catches, chasing down suspects who immediately surrender, and about 30 apprehensions, where a suspect is caught by the dog and puts up a fight.

"He caught hundreds of people and never once let me down on the street," he said.

Flannigan realized early in their partnership that Chesney had one of the best traits a handler/owner could hope for in a partner.

"It was like turning on a light switch," Flannigan said. "Even if he was in a fight with a bad guy, once it was over he would flip over on his back there on the scene and other officers could come over and pet his stomach."

Flannigan appreciated that trait as his family grew because Chesney lived with them.

When he met Kristin — also a Tampa patrol officer — about eight years ago, she already had a three-year-old son, Ty. Later, the couple had a daughter together and got married.

Chesney got along well with the family's other dog, a French bulldog named Dixie. And he was calm enough to bring to his daughter's school for the Great American Teach-in.

"We're very cautious with these dogs because we know what they're capable of doing," Flannigan said. "Some of them go 100 percent all the time. I was very lucky to have a dog like him who knew when it was time to go to work and when it was time to be a family dog."

About two and a half years ago, Flannigan bought a Belgian Malinois he named Pancho, donated the dog to the city and began to train him as Chesney's successor. About seven months ago, when he noticed that Chesney was slowing down in his older age, Flannigan took him off patrol duty but continued to work him at events as a bomb dog.

The transition to retirement can be difficult and confusing for police dogs, and for the first couple of weeks when Flannigan and Pancho would leave together for patrol shifts, Chesney howled the entire night.

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"He definitely had the drive and willingness to work, but in his old age I think he kind of settled down a bit," Flannigan said.

German Shepherds have a life span of about seven to 10 years, according to the American Kennel Club, though they can live several years beyond that. The work police dogs do takes a toll, so the plan was to make every day count when Chesney began full retirement next week and became a full-time family dog.

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Last week, Flannigan noticed Chesney was having trouble standing up. On Tuesday, he took the dog to a scheduled vet appointment, his last as a Tampa police dog.

Flannigan hoped the vet would diagnose arthritis, but she noticed Chesney was retaining fluid, then confirmed he was bleeding internally.

She suspected cancer and estimated Chesney had a day or two left.

Stunned, Flannigan broke the news to his family, and his parents and others came to the couple's Tampa area home that day to say goodbye. Daughter Harper, now 5 and closer to Chesney than to the family's other dogs, got off the school bus and smiled when she saw everyone gathered at the house. Her father had to explain that Chesney was very sick and hurting, so they needed to send him to heaven with the other family members and dogs they loved.

They fed Chesney a plateful of peanut butter and a couple of filet mignon steaks, then Ryan and Kristin took him to the K-9 office, a former fire station in the Sulphur Springs area. The squad tried to lighten the somber mood by cracking jokes like they usually do. Chesney got more steak.

After about an hour, the Flannigans loaded Chesney into a patrol car and and other members of the unit escorted them to the vet's office in Temple Terrace. By then, Chesney was in so much pain he could hardly stand up, Ryan Flannigan said, which is why Kristin was so surprised when the dog jumped up at the sound of the escort's sirens.

At the vet's office, member of the K-9 unit said their goodbyes, then stood in a line and saluted as Ryan Flannigan led Chesney into the building. The gesture made Ryan burst into tears.

Once inside, Ryan and Kristin spent their last moments with Chesney.

"We told him we loved him," Ryan said, "over and over again."

Contact Tony Marrero at tmarrero@tampabay.com or (813( 226-3374. Follow @tmarrerotimes.