Bryn started his life dumped and left to die on the streets of Auckland.
Now, the border collie/staffy cross has risen through the ranks to become one of the country's top Urban Search and Rescue (USAR) dogs.
If disaster strikes it will be Byrn helping save lives.
"It's amazing, this was a little pup someone just dumped, and left to die, and has turned into an animal who will be on the frontline in the worst of disasters," Pukekohe-based owner Alex Schanzer said.
He and his wife Rachel adopted Bryn from the SPCA in 2015.
When the couple visited him for the first time at the Māngere shelter, it was love at first bark.
"We were sitting there watching, and then he stopped what he was doing, saw us in the corner, came running over and jumped into our laps. We knew we had to have him after that.
"He is just the most wonderful dog. Very high energy, high drive. I knew we had to do something with him. He could not just be a pet, he needed a job."
Schanzer, a keen tramper, thought about training him as part of the Land Search and Rescue (LSAR) programme, which helps find people lost in the bush.
But it was quite a long programme, so they looked at USAR instead.
Schanzer took Bryn, then about 8 months old, along for a training session to see if he had the attributes.
"He flew through," Schanzer said.
Now, four years later, after tough weekly training, Bryn is at an advanced operational level - one of only six such dogs in the country.
Bryn and Schanzer are now part of the New Zealand Task Force, so if the country experiences another major disaster or is asked to assist in any overseas rescue missions they will be sent.
In the Christchurch earthquakes, USAR dogs were deployed to search through the rubble to find any signs of life.
Fortunately, in Bryn's short life, they have not been needed for any disaster relief just yet, Schanzer said.
"But we train every week, so we are ready."
Bryn is a lifeline dog, meaning he finds people buried under rubble, his light paws meaning he can get to areas where it is too dangerous for handlers to go.
Bryn and his teammates are trained to detect live human scent, and bark when someone is found, continuing until help arrives.
As part of the dogs' training, volunteers are hidden in rubble and the dogs have to find them.
"It is an amazing thing to be involved with, and especially over Covid we have been indundated with people wanting to volunteer," Schanzer said.
Not all dogs make it through the programme because of the high stress involved, Schanzer said.
"To get a dog with Bryn's background and to a point where he is today makes me very proud to be associated with him."
Thousands of dogs are rescued and adopted each year through the SPCA.
SPCA chief executive Andrea Midgen said it was "heartening" to hear Bryn's story, especially for the team who put hours into his rehabilitation when he first came into their care.
"Every animal is carefully matched with the right owner to ensure a happy and healthy relationship.
"In this particular instance we couldn't think of a better way of helping others than to be trained as a search and rescue dog.
"It's a full circle moment and he's a very special dog. It's easy to write some of these animals off, but it goes to show, with a bit of love and care, anything is possible."