How to transition your cat onto a new food

Sometimes, during a cat’s life, it may be necessary to change their diet. So how do you swap your cat onto a new diet? Taking things slowly and applying the following simple recommendations will help.

So, what’s the best way to swap your cat onto a new diet and how do you avoid problems along the way?

There are two things to bear in mind: cats can be suspicious of new foods - new flavours, smells and consistencies all have the potential to put your cat off eating. This is probably because cats in the wild are designed to eat a specific range of prey and anything outside of this range might be considered unsafe.

Secondly, a sudden change from one food to another can cause an upset tummy - possibly because their digestive system is made to process a limited range of foods. 

Why might you need to change your cat’s diet?

When you first get your cat or kitten, try to obtain some of their original food to use while they settle in and, if you choose to change their food, to help them gradually transition to their new diet. A change of home, owner and environment can be stressful and can sometimes cause an upset tummy, so a gradual change of diet is best. 

If you are getting your new pet from a breeder they are usually happy to give you some of the diet they were being fed. If this is not possible, just buy enough of the old diet to last two or three weeks. 

If your new pet has been on an unsuitable diet, weigh up the risks of remaining on the old diet for a bit longer against the risk of a possible tummy upset caused by a sudden change in food at an already stressful time. 

Many diets we feed our cats are called “life-stage” diets. These have been designed to meet the nutritional needs of a pet for their age and activity level: as a kitten grows through adolescence to adulthood, and then into their senior years, their nutritional requirements change and they will benefit from being fed a food appropriate to their life-stage. 

Some health problems may benefit from a change in diet to help manage the condition - these are prescription diets and are specially formulated to provide the nutritional needs of specific conditions. As well as prescription diets, your vet might recommend other types of diet, for example, if your cat develops an allergy to chicken and it might need to eat a fish-based food. 

If it’s necessary to make a more sudden switch from an old food to a new one e.g. to a prescription diet, your vet will explain the best way to do this, weighing up the risks and benefits of suddenly changing to a new diet.  

Occasionally your vet might suggest waiting to change to a prescription diet so that the transition occurs when your pet is feeling better - being unwell can reduce appetite and put them off the new diet. 

There is a variety of high-quality complete pet foods out there at a range of different prices and we know that feeding the best quality pet food is important to you, so if you would like advice on which food to choose, speak to your veterinary team or book a free Pets at Home nutrition consultation.

We can help you find a good quality pet food at a price that is affordable; helping you to save money while maintaining your pet’s health.  

If your pet is overweight or underweight it’s best to seek the advice of your vet or veterinary nurse before making changes to their diet: for weight loss, simply reducing the volume of food they are given could result in them receiving inadequate levels of some nutrients, and might mean your pet is constantly hungry. And, whilst it’s encouraging to see your pet lose weight, losing too much, or losing it too quickly, can be detrimental to their health.

There are plenty of specially formulated foods on the market that can help our pets lose weight whilst ensuring they are still getting the right nutrients, in the correct amounts, to stay healthy.

Always speak to your veterinary team if you have any questions or concerns. 

How do you switch your cat’s diet?

A gradual transition is the best way to reduce the chances of your cat refusing to eat or developing a tummy upset. How long you spend introducing the new diet and phasing out the old one will depend on a few things:

  • How big is the difference between the old and new food? For example, changing from a wet (or raw) diet to a dry one; is the change just between bags of the same food or a different flavour; or are you introducing a new brand, a life-stage diet, or a prescription diet? In general, the greater the difference, the longer the recommended transition period. Most cats will tolerate changing between different flavours of the same food without a problem. 
  • For a change in life-stage diet or to a prescription diet, it’s best to make the transition slowly, over about 14 days. 
  • If your cat has had a sensitive tummy in the past, or if this is the first time their diet has been changed, it’s best to carry out a slower transition over 14 - 21 days.

Days 1 - 3
Offer a teaspoonful of the new diet in a separate bowl. If your cat doesn’t eat the new diet at first, don’t worry, they might just need more time to try it and become familiar with it. As the days go by, gradually increase how much of the new diet you offer and reduce the amount of the original diet offered accordingly.

Days 4 - 6
Offer 25% of the new diet’s recommended amount (according to the food packaging) and 75% of the old diet. If one of the diets is raw keep the foods in separate bowls.

Days 7 - 9
Offer 50% of the new diet and 50% of the original. 

Days 10 - 13
Offer 75% of the new diet and reduce the original diet to 25% of the recommended amount.

Day 14
Phase out the old diet completely – now your cat should be on 100% new food.

What problems might occur?

If your cat won’t try their new food, don’t worry. Offer a small amount with each meal. You could try putting the new food down shortly before you offer your cat’s usual food to encourage them to try it when they are still hungry.  

If your cat eats the new food but then goes off it, try reducing the amount of the new diet until your cat is eating it again, and then gradually increase it once more. 

If, after several days, your cat still isn’t interested in their new food, consider changing to a different new diet.

When offering wet food, remember not to leave it down for long periods, as it can attract flies, it can go off and it can dry out. Ideally, serve regular, small helpings throughout the day. This can help keep the food fresh and more attractive to your cat.

Sometimes sudden changes of diet can upset a cat’s digestive system. Symptoms might include vomiting; soft faeces or diarrhoea; flatulence; or just not seeming themselves, especially if they go outside to toilet. They might also lose interest in food. 

Other things can cause tummy upsets: if you are concerned about your cat’s digestion, your vet team is there to help. Sometimes veterinary treatment may be required to settle things down.

If this happens during a food transition, try reducing the amount of new diet and then monitoring your cat closely to see whether their tummy is settling down. They should start to improve after a day or two at the most. If your cat still seems to have a tummy upset, you may need to remove the new diet altogether. If your cat is back to normal once they’re eating their original diet, try re-introducing the new food after a few days. However, if this also results in an upset tummy, you might need to find an alternative food.  

Monitoring your cat on their new diet

Be prepared for it to take a few months, and a bit of trial and error, to know whether a new food suits your cat. When your cat is on a suitable diet you can expect them to have a shiny coat, bright eyes and, provided their teeth and gums are healthy, inoffensive breath. Their faeces should be firm and there should be no flatulence.

You might need to adjust the amount being fed to keep your cat’s weight within a normal range or body condition score (BCS).

Your vet team will also be happy to help you with body condition scoring. It’s a good idea to reassess BCS every couple of weeks, adjusting the amount you’re feeding until your cat is maintaining a normal BCS.

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