A KITTEN has almost died after its owners fed it a strict vegan diet.

The horrific case at a North Melbourne animal hospital has prompted a warning about the dangers of people "forcing ideologies" on their pets.

Lort Smith Animal Hospital veterinarian Leanne Pinfold said the kitten was brought in this month by its owners, who were believed to be vegan.

She said the kitten's diet of potatoes, rice milk and pasta had caused it to become critically ill.

"It was extremely weak and collapsed when it came in. It was almost non-responsive," Dr Pinfold said.

The kitten was given fluids via a drip, placed on a heat pad and fed meat.

It remained in hospital for three days after which the kitten's owners were given meat to feed their pet at home, she said.

Dr Pinfold said as obligate or true carnivores, cats needed meat to survive.

She said people who wanted a pet that did not eat meat should consider other animals, such as rabbits.

"Concern for animal welfare has to include a biologically-appropriate diet," she said. "You can't force your ideology on the cat.

"Carnivores will seek out meat and your cat is possibly more likely to go hunting and kill local native fauna if you deprive it of meat.''

Dr Pinfold said she had not come across a similar case in her 11 years as a veterinarian.