What happens if your cat really won't eat the new food, no matter how slowly you introduce it?
Fasting a cat can be extremely dangerous, as they can develop a serious condition known as hepatic lipidosis. For cats who are still resisting the slow change, or for whom a slow change is not advisable, a medically supervised switch may be necessary.
"I know a vet who works with cats who need rapid, safe diet changes while they are hospitalized," said Pesch. "She purées the food and puts it into plastic squeeze bottles, cutting the top off so there's a big enough opening to squeeze the food through. Then she basically bottle-feeds the cats. She says that in three days, most cats are eating the food without a problem. After a few days, their taste buds adjust and the new food tastes OK to them."
Are there cats who simply will never, ever change, no matter what their owners try? Probably not, but the process can be extremely difficult for some cat owners. "I would say that the failures usually come from the owners not being able to cope with their cat's reaction, rather than the cats themselves," she said. "The cat bugs them constantly and becomes unmanageable at not being fed something they consider to be food."