The cross-bred labrador, blue heeler and border collie were at the forefront of an attempt to find people trapped in buildings levelled by the city's February 22 earthquake.
And although the last known survivor was extricated from rubble the following day, nine local dogs and their handlers continued to search the key sites in hope of uncovering a miracle inside the Canterbury Television Building and Pyne Gould Corporation headquarters.
"They worked really well and found a number of people," said a satisfied Tim Drennan, who handles Boo the lab.
"They've been all over, all the major sites in the first few days. Through that stage we did 80 searches throughout Christchurch."
Mr Drennan and fellow handler Brenda Woolley could not quantify exactly how many people owe their lives to those fearless canines with the acute sense of human smell.
Time, after all, is also of the essence.
Once a bark alerts the handler to a "live" find, search and rescue personnel take over and the dog progresses to the next search area.
"We don't know who many, or what, or who ... we just move on to the next job," Mrs Woolley said.
Naturally, not all shapes, sizes and temperaments are cut out for padding around tangled wreckage in confined spaces.
The three on show today clearly met the requirements - and with only 11 dogs up to the task nationwide, the selection process is obviously stringent.
"If we can get a 12-14-month-old dog, they can be operational in six months, a younger dog can take two years. It also depends on the experience of the handler," she said.
Bravery is a prerequisite for man, woman and beast - aftershocks do not discriminate.
Technicians and engineers accompany the handlers, which gives peace of mind though no guarantee of safety, Mrs Woolley admitted.
Fortunately everyone emerged from their ordeal unscathed, with only a couple of dogs receiving superficial wounds, and they are likely to enjoy a lengthy convalescence.
The USAR dogs are a tough and rarely sighted breed. Before Christchurch's first earthquake on September 4, Bo was basically a family pet.
