Changing Dog Food: A Clear 7-Day Switch Plan

by Ben, co-founder

For a healthy adult dog, a practical starting plan is 25% new food for days 1 and 2, 50% for days 3 and 4, 75% for days 5 and 6, then 100% on day 7. The important bit is not finishing on time. It is moving at the pace your dog is comfortably tolerating.

PDSA's UK guidance uses an even gentler transition over roughly two weeks. That is a sensible option if your dog has been unsettled by food changes before. If a vet has prescribed the new diet or told you to switch differently, follow their plan instead.

The 7-day dog food transition chart

Those percentages refer to the full daily portion of each food. They do not mean “put two equal scoops in the bowl”. Foods can have very different feeding guides, so equal grams may give much more or less food than you intended.

Work out the mixed portion correctly

Suppose the old pack recommends 240g per day and the new pack recommends 160g per day for your dog. Your example transition would be:

Choose the pace that fits the dog

You do not get extra points for reaching 100% quickly. If the dog is settled, eating and behaving normally, move to the next ratio. If not, the useful response is to adjust the plan, not to force the calendar.

If the new food is refused

First, check the simple things. Is the amount much bigger than the old meal? Has the bag been stored properly? Is the dog rejecting the new food only, or have they lost interest in all food?

For a dog who is otherwise bright and well, stay at the last accepted ratio for another day or two. You can offer the meal at the usual time and remove it after the normal feeding window rather than turning each refusal into a parade of extras. Do not add a new topper every day if you are trying to learn whether the food itself suits them.

A dog refusing all food, repeatedly vomiting, seeming painful or becoming flat is a different situation. That needs veterinary advice, not a more inventive bowl.

If stools soften during the switch

A mild, short-lived change can follow a sudden or unfamiliar diet change. PDSA advises that diet-change diarrhoea often settles quickly, but the dog should improve and stay hydrated.

1. 1

   Hold

   If the change is mild and your dog is otherwise well, repeat the current ratio rather than adding more new food.

2. 2

   Step back

   If it is not settling, return to the last comfortable ratio. Once stools are normal again, progress in smaller steps.

3. 3

   Stop and call

   If signs are severe, keep returning, or the dog seems unwell, stop treating it as a routine transition and speak to your vet.

For more detail on the ordinary settling-in pattern, read soft poos after a food change: normal or not?

If you are switching because of itching or gut signs

Changing food can be a sensible, relatively simple next step for a dog with persistent or recurring signs, provided there is no acute warning sign that needs the vet first. But be clear about the question you are trying to answer.

If you simply want to see whether a different complete food suits your dog better, use the transition plan above and keep a short record of stools, appetite, skin and ears. Try not to change treats, supplements and three other things at the same time, because you will not know what made the difference.

If you are trying to test for a food allergy, that is a stricter process. A diagnostic elimination diet needs an appropriate diet, exclusive feeding and a proper trial period. The mixed-food transition days are preparation, not part of the exclusive trial clock, because the old food is still being eaten.

Read how to conduct an elimination diet for dogs before you start. It covers diet choice, treats, flavoured medicines, duration and re-challenge. If you are not sure whether food is a sensible avenue at all, use the food-allergy next-step check. It gives you the result before the optional email follow-up.

Frequently asked questions

Can I change my dog's food straight away?

Sometimes a vet will want an immediate change, but for a healthy dog making an ordinary switch, gradual introduction is the gentler default. If the old food is unavailable, recalled or suspected of causing harm, ask your vet or the manufacturer rather than improvising a long overlap.

How long should changing dog food take?

Seven days is a practical starting plan. Ten to fourteen days can be more comfortable for a dog with a sensitive history. The right finish date is the one reached without forcing the dog through worsening signs.

Does soft poo mean the new food is wrong?

Not automatically. It may reflect the speed of change, the amount fed, another dietary extra or a separate health problem. Hold or step back if the change is mild and the dog is otherwise well; speak to your vet if it is severe, persistent, keeps returning or comes with other signs.

Can I use the same chart when changing from wet to dry food?

Yes, use the proportions of each product's own daily feeding amount. Do not use equal bowl volume or assume that 100g of one format replaces 100g of another.

When does an elimination trial start?

Start counting the formal trial only when the dog is eating the chosen trial diet exclusively, with no old food, scraps, treats or flavoured extras that your vet has not approved. The complete elimination-diet guide explains the protocol and evidence.

Sources

• PDSA: Your dog's diet and how to change food
• PDSA: Diarrhoea after a change of food

Soft poos after a food change: normal or not? →How to conduct an elimination diet for dogs →Food-trial mistakes that reset the clock →

General guidance only. It cannot diagnose the cause of vomiting, diarrhoea, itching or appetite loss. If your dog is unwell, getting worse, very young, old or living with another condition, contact your vet.

Last updated: 5 August 2026