Vets are worried about the current fad of feeding raw food to pets, saying some owners are killing their pets with kindness.

The idea of raw feeding is to give animals food resembling what they'd get if they were in the wild - a mix of raw meat, bone, and offal.

Veterinarian Dr Mark Robson told the NZ Herald the chunks of indigestible bone are often too big.

"In the wild a dog would chew on the bones of a wildebeest or a zebra or whatever and would gradually absorb the bone but in these diets they're consuming too much."

Dr Robson said pieces can get lodged in the animal's digestive tract, with terrible outcomes.

"So then the bone fragments or bones are stuck in the oesophagus permanently, or until we take them out, and if they stay there they're fatal."

Dr Robson said he has had over 120 cases of the diet-gone-wrong in the four years since the trend kicked off.

Months ago he had a case of a dog with its bowel pierced by bone. Despite an operation, the dog died and left the owners with a $20,000 bill.

He also said a solely raw food diet doesn't have enough minerals for puppies, which could affect bone development.

Ponsonby Vets' lead veterinarian Gareth Dunkerley agreed, pointing out that cats and dogs only live for around six years in the wild.

"Animals looked after by us on premium diets tend to live much longer, healthier, happier lives," he said.

Raw Essentials founder Dr Lyn Thomson said health hazards were possible, but this was primarily due to people not being educated about how to raw feed correctly.

She said there are thousands of people who have seen their pets health improved by raw feeding.