How to Switch Your Pets Diet

DrPaul -

How to Switch Your Pets Diet

Just as our own diets and nutritional needs change across the years, it’s likely that our pets’ needs might change too. As pet owners, this means we’re likely to switch our pets’ diets during their lifetime, but why might it be necessary and how do you go about it?



  • AGE - Optimum nutrition to meet developmental stages can trigger alternative dietary needs, for example transition from kitten or puppy foods to adult diets or, at the opposite end of the timeline, switching from a working dog diet to a diet suitable for older dogs.


  • CLINICAL / HEALTH - For some pets, allergy or illness trigger a swap from commercial brands to a prescription diet. Swapping as part of a weight management programme might also be necessary for your pet.

Making these changes should never be done in a hospital environment as your pet may associate the diet with the stress from that environment/hospital experience. Of course, it’s advisable to obtain the relevant prescription and professional guidance from your veterinarian and clinic, but start the actual transition at home.

  • SUPPLY & PRODUCTION - The UK’s seen a strange time, with the impact of the pandemic and ensuing cost of living crisis resulting in some commercial brands of pet food no longer being regularly available, due to supply chain issues and production costs. Similarly, local outlets for buying pet food may have closed.

Where a favourite food is now no longer regularly or locally available, this often forces the change to an alternative brand. 

  • COST - Alongside this, cost and managing household budgets is also a factor causing many pet owners to switch to more affordable diet options. Pet food banks actively support pet owners remaining together with their pets by providing food, another reason for transitioning to an alternative, affordable brand, or diet. 

Listen to Dr Paul's podcast about the growing need for pet food banks in the UK here;




Unless your vet advises an immediate change of diet, the golden rule is to take your time.  It's never a good idea to transition to a new food quickly as a rapid change of diet might cause tummy upsets which could put your pet off the new option or food altogether, causing you and the pet additional issues.


Instead, allow up to 2 weeks for a full change of diet. To pace the process, I’d recommend:


Day 1 - 3: Introduction

  • Maintain usual mealtimes but introduce a small teaspoon of the new food in a separate dish. No mixing yet, just allows your pet to become familiar with the sight and smell of the new food. 
  • Note, if you’re swapping your pet to a raw food diet, always offer the raw food in a separate bowl throughout the transition process.


Day 4 - 10: Transition time

  • Unless your pet is very picky, start to mix small quantities (up to a teaspoon) of the new food with the previous variety. 
  • If your pet is eating all their food as normal, without showing signs of digestive distress, then slowly increase the amount of new food. Reduce the previous brand by an equal amount, to avoid over-feeding which could cause tummy upset too!
  • If your pet suddenly goes off the new mix, don’t worry, just return to a stage when they were clearing the dish. Continue with that mix for a few more days, before increasing again but in smaller amounts. This should help maintain your pet’s interest in the food and progress the transition at the same time!


Day 10 - 14: Complete change

  • Through the gradual increase of the new food and reduction of the old food, you’ll gently move towards meals which consist only of the new diet. Once the previous food is completely phased out, the transition is complete.
  • If your transition is progressing more slowly, for instance to ensure your pet is actually eating, don’t worry. Adapt the increase / decrease to suit your pet’s needs and allow a few more days. 




If at any point there seems to be a real problem, speak with your vet in case an underlying health issue is affecting appetite or ability to eat. For instance, transitioning from a wet diet to a dry mix might highlight dental issues for a pet, so it’s worth checking out any possible problems.


Finally, if you have more than one pet? If they’re going to be on different diets, try to also introduce separate feeding areas slowly for them, if you can. If this isn’t possible, and your pets are the same species, consider the possibility and safety of introducing this new diet to both pets. As ever, if you are unsure, please speak to your vet for advice specific to your pet.



Paul Manktelow

Veterinary Surgeon

Dr Paul Manktelow is a vet who's worked for almost 20 years on the front line in some of the UK's busiest veterinary hospitals. Paul also appears regularly in the media as a TV and radio presenter, writer, public speaker and podcast producer.