A pet cat has stunned an animal expert by surviving 19 hours in his owners' freezer.

Sarah Crombie, 27, discovered Krillen lying stiff and semi-conscious on a bag of dog food when she went to get a loaf of bread.

I was looking in there and I heard this funny noise," said the Te Kuiti mother-of-two.

"It was sort of a 'miaow' but he was so half-frozen he couldn't get the noise out properly, poor thing. So I look down and I see this grey fluffy thing sitting on top of the bag of dog food under a rack."

Her partner Sid Sisson had shut the top-loading freezer the night before, not realising Krillen was inside.

On discovering the 1-year-old Sarah feared the worst, as the freezer is kept on its coldest setting, about -18C.

"I raced inside to get Sid and as I came out, Krillen rolled off the bag in an attempt to get out, but he was that frozen he just rolled to the bottom of the freezer on his back," she said.

"At first we thought his eyeballs were frozen. I've never seen a cat with such big eyes."

Fortunately, Sid, 28, knew it was essential to raise the body temperature of hypothermia sufferers slowly. So he put the cat under his shirt and got into bed with him.

The dairy farmer kept Krillen under blankets and against his bare chest for three hours until he thawed out.

"I was sitting on the other side of the bed and the whole bed was vibrating from this cat shaking," said Sarah.

Amazingly, Krillen seems to have emerged from his ordeal unscathed. "But I tell you, he doesn't go near the freezer any more," said Sarah.

Dr Nick Cave, senior lecturer at Massey University's Veterinary Teaching Hospital, said Krillen's survival was impressive and probably down to Sid warming him up slowly.

He knew of another cat that had survived in a freezer for more than 24 hours and days later developed signs of frostbite on its ear and toes. It also developed signs of kidney damage.

Although Krillen was frostbite-free a week later, Cave suggested Sarah and Sid take their pet to be checked for internal damage.

There has been little research into cats' ability to survive extreme cold, but dogs are a different story. Before the days of animal rights activists, scientists put huskies into freezers to see how they would cope.

In a 1959 study six out of seven dogs maintained their body temperature for up to 27 hours at -50C, and for another five hours at -79C.

But a 1952 study found that at -5C, a cat's metabolic rate rose by almost a third.

"So putting a cat in the freezer means it would presumably have to use up an enormous amount of energy to maintain its body temperature," said Cave.