Changing diets abruptly can wreak havoc on a cat's digestive system and result in abdominal pain, vomiting, and diarrhea. In turn, that upset can disrupt the delicate gut flora balance, and then the kitty may end up with chronic GI problems.
Sometimes you do have to change your cat's food. Perhaps your vet has recommended a new diet or you just want to switch for other reasons. Here are some tips for changing your cat's food while minimizing the risk of her developing GI upset.
At any step in the process, if your cat develops GI problems, go back to the previous step until things are back to normal and then increase more slowly from there.
If your cat stops eating at any point, contact your veterinarian. Cats that stop eating suddenly are at risk for developing hepatic lipidosis, which is life-threatening.