It was January 2016, and the police officer had been shot in the leg with his own gun, severing a major vein, by a man holding a doctor hostage with scissors in the emergency department at Nepean Hospital.
He thought he was going to die, and his last thoughts were for his wife Sandra and three children and how much he loved them.
"You look at things a little differently now. It was touch and go for a while, I was in intensive care for a week or so," he says from his home in the Lower Mountains.
"Mates of mine told me my opinion is stronger than it used to be and I try to take the kids away more and do more stuff on holidays.
"It's not all about going to work now, it's a bit more fun."
Two year ago the police officer put pen to paper with the help of crime reporter and author Simon Bouda, and the result is Man's Best Friend, released on August 6.
It tells Sgt Warburton's story from growing up in Sydney's inner west and Kellyville, to joining the dog squad and chasing down crims with his beloved dogs.
One of the dogs he worked with for five years is sniffing around the backyard. Explosives detector dog T-Bone, a Springer Spaniel, retired from active duty a year ago, and now calls the Warburton household home.
"It's good for me to have a dog in the backyard and get out and play with him and take him for walks."
He'd love to run and ride a motorbike but injuries sustained during the Nepean Hospital incident have meant he's been unable to return to the highly physical job within the dog squad.
"It's better than it was initially but it's still not ideal. I've got to have this splint on my leg which runs the length of my leg to my shoe and keeps my foot up, cause I've got foot drop so I can't control my ankle.
"And I wear this pressure stocking because my leg swells if I don't wear it. And I've got limited feeling from my knee down," he explained.
"I'm pretty lucky though, I can still walk around and get out with the kids and walk the dog. There's always people that are worse off than I am."
Sgt Warburton now trains new dogs and handlers.
"I haven't worked a dog since injury. The plan is to get back to duties one day. How long that's going to be I'm not too sure. It's certainly more realistic now than I thought it was three years ago," he said.
Whether there will ever be another dog like Chuck, his crime-busting partner for five years, who he'd left in the car when called into the emergency department, will remain to be seen.
In the busy hospital, Chuck could have mistakenly bitten hospital staff trying to help the officer, as he was trained to protect his handler.
"Chucky was a special dog there's no doubt about it. I had Chucky for a long time, we did a lot of good things together and he saved my skin a number of times as well," Sgt Warburton said.
In 2012 the pair helped capture one of Australia's most wanted fugitives, Malcolm Naden, who'd been on the run for nearly eight years, wanted on charges including murder and aggravated indecent assault.
Police had surrounded a hut in Gloucester and, as Naden came outside, Chuck pounced on the fugitive, sinking his teeth into Naden's leg.
"I was lucky enough the door he came running out of was the door I was standing at," Sgt Warburton said. "I went in with Chucky and did what we needed to do.
"It's a proud moment as a handler."
When Sgt Warburton was shot at Nepean, Chuck would have heard the gunshots and the screaming, and was "beside himself" when handlers retrieved him from the officer's car.
The pair were reunited by hospital bedside a few weeks later. "He was licking my face, he was just so happy to see me. It was great for me to see him too," Sgt Warburton recalled.
Then five months later, at age eight, Chuck unexpectedly died one night. He was to come home to the Warburtons that week.
"Dogs are funny sometimes, they are away from Dad or family and they think 'this is not much fun, I've had enough.' But not long after Chucky died his brother died as well. Whether there was a genetic thing there you don't know, but Chucky's sister China is still going strong and she's retired these days.
"That was a pretty sad time," he said.
The bond between handler and dog can never be underestimated. "I spent more time with Chucky than I did with Sandra. You get a really close bond and you get really tight with them."
But it's Sgt Warburton's family who have seen him through his long road to recovery both physically and mentally, as he also battled PTSD after the shooting.
"My family were fantastic through the whole thing. Not just Sandra and the boys but extended family as well."
Writing the book has also helped in dealing with the PTSD. "It's nice to get it down on paper and talk about it and get it out there," Sgt Warburton said. "The more and more you talk about it the easier it gets."
When the Nepean Hospital incident came before the courts in 2018, and the shooter, Michael de Guzman, was found not guilty on the grounds of mental ill health, Sgt Warburton felt let down.
"Personally it's disappointing. I thought there was enough to get a conviction outside the Mental Health Act but the judge saw it another way," he said.
While his life isn't what it once was, Sgt Warburton would still recommend policing.
"I love the dog squad, I love the cops, I've been there 20 years and I still recommend it to anyone to do, it's a great job. You might get injured along the way, but it's great fun."
And when his eldest child Angus, who's 12, toys with the idea of becoming a dog squad officer, his dad is supportive: "If that eventuates that will be a proud moment."