Your cat’s veterinarian advises you to change your pet’s diet. Perhaps she is overweight and should be eating food that is lower in calories. Or she has developed heart or kidney disease and requires a prescribed meal plan that has more or less of particular nutrients. Or maybe she needs more fiber or more water to restore her health.
You follow the advice but find right away that the new food does not agree with your cat. She develops diarrhea, a rumbly tummy, or some other sign of gastrointestinal distress.
It seems like a Catch-22. If you take her off the food, she will not get well. And if you leave her on it, she will remain sick and uncomfortable from GI discomfort. Fortunately, there’s a very high chance this is not the dilemma it seems.
Gradual introduction of the new diet is key
Often, it’s not the food that’s the problem but simply the pace at which you introduce it. “Some cats need as much as a month to six weeks to make the transition comfortably,” says Tufts board-certified veterinary nutritionist Deborah Linder, DVM.
But most cats need only a week or so. The Tufts Clinical Nutrition Service offers guidelines for changing the ratio of old to new food day by day for seven days. (See the box below.) Note that the guidelines are for calories, not for how much you scoop into a measuring cup. That’s because a cup of the new food may contain more or fewer calories than a cup of the old. You’ll want to check the label for calories.
Even if you follow the instructions to the letter, your cat may still have some soft stools and stomach gurgling for a bit. That’s okay as long as she is still her usual self with her usual amount of energy. You’ll just want to slow down the transition a little. Go back one step to the previous ratio for a day or two and then try moving forward again.
If the GI problems persist or are more severe than garden-variety stomach upset, talk with the vet. You may have to go even more slowly — or switch to a different food. There’s usually more than one brand of food to address a health issue.
