A dog eating. Changing your dog or cat's food should be done gradually

How to Change Your Pet’s Food Without Upsetting Their Tummy


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Your pet’s diet is key to their overall health. What happens when you need to switch up what they’re eating? Changing your dog’s or cat’s food suddenly can upset their stomachs and cause other issues. So whether you’re switching to a new brand, formula, or type of food, it’s important to do it gradually.

In this blog post, we’ll walk you through the steps on how to change your pet’s food without upsetting their health balance. We’ll also discuss some of the reasons why you might need to change their food and what to look for in a new food.

Kittens eat a healthy diet of wet and dry AAFCO approved cat food brands. Changing your dog or cat's food should be done gradually

Changing dog/cat food – Why would you?

You’ve been feeding your furball a particular brand since you became a pet parent, so why would you want to change it all of a sudden? There are a few reasons why, such as these:

  • Your pet’s dietary needs have changed. This may happen as they age. For example, older dogs may need a food that’s lower in calories and fat, while younger cats may need a food that’s higher in protein.
  • Your pet has developed a food allergy or intolerance and you need to switch them to a food that doesn’t contain the offending ingredient.
  • Your pet’s health has changed. If your pet has developed a health condition, such as kidney disease or pet diabetes, you may need to switch them to a food that’s specifically formulated for that condition.
  • You’re simply looking for a new food. Perhaps you’ve seen new food on the market that looks like it could better meet your pet’s needs or is more affordable (we know the cost of owning a dog or cat can be big). Remember to keep their nutrition and life stage in mind first and foremost when switching over.

Why does changing dog/cat food upset their stomach?

Not all pets get upset tummies when you change their food. However, it’s a common occurrence, especially if they have a sensitive stomach. There are a few reasons why changing your dog’s or cat’s food can upset them in this way:

Gut health

Their digestive system needs time to adjust to the new food. The bacteria in their gut are used to breaking down the nutrients in the old food, so they need time to adapt to the new food. This can cause gas, bloating, and diarrhoea.

Good gut health is an essential part of a healthy, happy life for your furball. Read our top tips for great dog gut health and Purina’s 8 tips to improve and restore your cat’s microbiome.


The new food may contain ingredients that your pet is allergic to. This can cause an upset stomach, as well as other symptoms such as itching, hives, and respiratory problems. Read more on allergies and related health conditions here:


The new food may be of a different texture or flavour than the old food. This can also upset their stomach as they may not be used to the new taste or texture.

a cat eats dry pet food

How to change their food the right way

If you’re concerned that changing your dog’s or cat’s food may upset their stomachs, there are a few things you can do to reduce the risk:

  • Start by mixing a small amount of the new food with their old food. Gradually increase the amount of new food over the course of 7-10 days. This will give their digestive system time to adjust and reduce the risk of an upset stomach.
  • Choose a food that’s similar in texture and flavour to their old food. This will help to make the transition easier for their digestive system.
  • If your pet does have an upset stomach, stop feeding them the new food and consult with your vet. They can help you to determine the cause of the upset stomach and recommend a food that’s better suited for your pet.

In general, most dogs and cats will adjust to a new food without any problems. However, if you’re concerned about their reaction, it’s always best to err on the side of caution and transition them to new grub gradually.

little girl plays with puppy while it eats its food. Changing your dog or cat's food should be done gradually

What to look for in a new food

When changing your dog’s or cat’s food, there are two key things you should keep in mind:

  1. The age, breed, and activity level of your pet. Make sure to choose a food that’s specifically formulated for their stage in life.
  2. The nutritional content of the food and the quality of ingredients. We have some great resources on that here:

What else do responsible pet parents do?

Understanding how to go about changing your dog’s or cat’s food is part of being a responsible pet parent. So is having adequate pet insurance. PD Insurance is dedicated to a long-term vision of consistently providing pets and their people with softer landings in the most crucial moments.

Our fur kids are prone to many illnesses and accidents. A value-rich, flexible pet insurance plan from PD Insurance will help you cover the cost of a wide range of treatments. Why not get a quote today?

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