The searchers and the dog had to battle blizzard conditions, with winds of 70km/hour, snow and ice in exposed places before they eventually found the couple at five that evening.
Mr Shepherd says the temperatures when taking the wind chill factor into account were well below freezing.
"The police dog was covered in ice and being blown sideways by the wind."
Mr Shepherd says while the couple, who come from the Australian state of Victoria, were prepared for one night in the bush in mild weather - they weren't prepared for two nights in blizzardy conditions.
He says things would have been "dire" if the couple had been forced to spend another night in the bush.
"Because of the cold and the wet conditions they would have had a high chance of getting hypothermic."
Mr Shepherd says it shows just how quickly New Zealand weather can turn.
"These spring storms can be killers."
His advice for others looking to go for a spring-time hike is to seek local advice.
"It's all very well to tell them to go to the website, but have a yak with the locals?these face to face conversations are valuable."
He says it's likely if the Australians had sought this advice, they'd have been advised against going on the hike in the wet conditions.
