How to switch your cat’s food without it refusing or getting an upset stomach
Switching a dog’s food is usually a matter of patience. A cat also has to be persuaded, because it distrusts anything new and may prefer not to eat at all rather than try it. And a cat that does not eat is a serious problem. This is how to do it properly.
Why it is trickier with a cat
Cats learn what counts as food during their first months of life, and many adults are neophobic about food: they distrust any new smell, texture or shape. On top of that, they link food with how they felt after eating it, so if a sudden change gives them nausea or diarrhoea, they may refuse that food for a long time. Most importantly, you cannot play the “it will eat when it is hungry” game. A cat, especially an overweight one, that goes more than a day or two without eating can develop hepatic lipidosis, a serious liver disease. With cats, hunger is not a teaching tool.
Before you switch: is it necessary?
If your cat eats well, is a healthy weight, has a good coat and normal stools, do not change its food just to try something or because you saw an offer. The reasonable motives are different: moving from kitten to adult food at around a year, neutering, reaching senior age, a veterinary diagnosis, a problem the current food does not solve, or the product being discontinued. Changing every few months does not give useful variety either: if you want to avoid a fussy eater, it is better for it to get to know several textures of wet food from a young age than to keep rotating dry foods.
The transition step by step
The classic schedule works for most cats, although it is best done more slowly than with dogs: over ten to fourteen days. For the first three or four days, a quarter of the new food mixed with three quarters of the old. For the next three or four, half and half. Then three quarters new and one quarter old. And finally, all new. Mix them well in the bowl so it cannot pick out the kibbles, because many cats do exactly that with astonishing precision. Keep the same total portion in grams and, if the new food has a different number of calories per gram, adjust so the cat gets the same energy.
If it leaves the new food in the bowl
It is common for a cat to eat the old kibble and leave the new. If that happens, go back a step and stay there for a few more days. Several tricks help: offering the new food as a treat from your hand during play; putting it in a treat-dispensing toy so it “hunts” it; or mixing it with a little of its favourite wet food. Some cats accept a food more readily if the kibble is similar in shape and size to the usual one. And do not put only the new food in the bowl to see if it gives in: the most likely outcome is that it waits, and you end up giving in late, with a cat that has gone a day without eating.
Changing wet food
With wet food, a change of flavour is usually easier, because it smells stronger and is more appealing, but texture matters a lot: there are pâté cats, chunks-in-gravy cats and mousse cats, and they find it hard to move from one to another. Mix gradually, mashing the new food into the old to even out the texture, and serve it slightly warm, never cold from the fridge, because smell is what wins a cat over. If you are moving from dry to wet or the other way round, the transition can take several weeks, and it helps to start by offering both in separate dishes so it can try without pressure.
The stomach: what is normal and what is not
During the switch, slightly softer stools or a bit more wind can be normal and usually pass within a few days. If diarrhoea appears, go back a step and move more slowly. What is not normal is repeated vomiting, diarrhoea that lasts more than a couple of days or contains blood, lethargy, or the cat stopping eating. In those cases, stop the switch, go back to the previous food and call the vet. Sometimes the problem is not the new food but a coincidence, and it is worth ruling that out.
When the vet asks for the change
Veterinary diets, such as renal, urinary, gastrointestinal or hypoallergenic ones, are part of the treatment, and the transition is adapted to how urgent it is. With a urinary diet to dissolve struvite stones, for example, the vet may advise a faster switch and that the cat eats only that food, with no treats or other foods, because any extra spoils the effect. Renal diets are less tasty and some cats refuse them: if that happens, do not leave it without food and tell your vet, because there are several brands and textures and one that the cat accepts can almost always be found.
Cats that only eat one thing
Some cats have eaten the same dry food or the same brand of pouches for years and refuse everything else. That becomes a problem when the food disappears from the shops or when the cat falls ill and needs a different diet. To avoid it, ideally a kitten should try several textures and flavours of complete food. If it is already an adult and very fussy, introduce new things in tiny amounts, as treats and without replacing anything, over several weeks. The aim is not to change its diet but to widen its repertoire, so you have a plan B on the day you need one.
Cats that eat elsewhere
If your cat goes outdoors, or if there are several cats at home, sometimes the problem is not the new food but that it eats somewhere else or steals its companion’s bowl. To manage a switch in a multi-cat household, the most effective approach is to feed them in separate rooms or use microchip feeders, which only open for the registered cat. They cost between €100 and €200 in Spain, but they solve the problem of different diets under one roof at the root, such as the cat with kidney disease living with a glutton.
Common mistakes
Switching abruptly one Monday because the old bag ran out is the first: buy the new one before the old one is finished. The second is reading refusal as fussiness and waiting for hunger to win. The third is adding tins, treats and pieces of chicken to persuade it, so it ends up eating everything except the dry food and putting on weight. And the fourth is changing brand every week when something does not agree with it, without giving the gut time to adapt or finding out what is going on. Patience, gradual mixing and making sure it eats every day: that is the whole secret.
Switch food over ten to fourteen days, mixing in increasing proportions of the new one. If the cat refuses, go back a step instead of leaving it without food: a cat that goes more than a day or two without eating is at risk of hepatic lipidosis.
Educational content from Michipedia, translated from the Spanish original. It does not replace the advice of a vet or a feline behaviour specialist. Every cat is an individual.