How to switch your dog’s food without upsetting their stomach
Most of the time a dog is “upset by a new food”, the food is innocent. The changeover was just too quick. A dog’s gut runs on a microbial population tuned to whatever it has been eating, and that population takes several days to re-tune. Give it those days and the vast majority of switches pass without incident.
The 7-day transition
Proportions by volume of the daily ration. Keep the total the same throughout - you are changing what is in the bowl, not how much.
- Days 1-2: 25% new food, 75% old
- Days 3-4: 50% new, 50% old
- Days 5-6: 75% new, 25% old
- Day 7 onwards: 100% new
Mix the two together in the same bowl rather than feeding them as separate meals. The point is a gradual shift in what reaches the gut, not alternating between two diets.
When to go slower
Stretch it to two or three weeks, moving in smaller steps, if your dog:
- has a history of digestive upsets or a diagnosed sensitivity
- is a puppy under about four months
- is elderly, or recovering from illness
- is moving between very different formats - kibble to raw, for instance
- has had a rough time with a previous switch
There is no downside to going slowly beyond patience. If in doubt, take the extra week.
What is normal, and what is not
Some digestive noise during a transition is expected. Knowing which is which saves both unnecessary worry and dangerous delay.
Normal, and no cause for alarm:
- Softer stools for two or three days
- More wind than usual
- Slightly reduced appetite as the taste changes
- A change in stool colour or volume - a food with different fibre or meat content will do that
If it goes wrong
Assuming none of the warning signs above, and your dog is otherwise bright:
- Go back a step. Return to the last ratio that was fine and hold there for a few days.
- Then move in smaller increments. Ten percent at a time rather than twenty-five.
- Check the fat content. A big jump in fat is a common and frequently missed cause of loose stools. Compare the analytical constituents on both packs - if the new food is considerably richer, that may be the issue rather than the transition itself.
- Count the extras. Treats, chews and scraps have not paused just because the food is changing, and they are a variable you can remove.
If a slower transition still fails, the food may genuinely not suit your dog. Our sensitive stomach guide covers how to work out what is actually causing it - which is a longer process than most people expect.
Special cases
Switching to raw. A bigger change than usual, and some raw feeders prefer a clean switch after a short fast rather than mixing formats. Opinions differ genuinely here. If you mix, go slowly. Our raw feeding guide covers the wider picture.
Puppy to adult food. Same 7-day method, timed by breed size rather than birthday - see the puppy feeding guide. Remember the daily amount changes as well as the food.
Onto a prescription diet. Follow your vet’s instructions, which may well be to switch immediately. Clinical need beats gut comfort.
Between flavours of the same range. Usually barely needs a transition at all - a couple of mixed meals is plenty.
How to judge the new food fairly
Give it four to six weeks after the transition finishes before deciding. Judging a food during the changeover tells you about the changeover.
What to look at:
- Stools: firm, consistent, and not dramatically larger in volume
- Coat: takes longest to show - a full growth cycle, so six to eight weeks minimum
- Energy and weight: stable, with body condition holding
- Enthusiasm: a dog who eats willingly rather than reluctantly
If all four look good, you are done. If you want to see how the two foods differ on paper, put them side by side in our comparison tool - ingredients, analysis and score together.
Where to go next
- Browse the directory and sort by score to find your next food
- Check the daily amount for the new food - calorie density changes, so grams do too
- How our scoring works, if you want to know what a good food looks like before you choose
How long should it take to switch dog food?
Seven to ten days for most dogs. Start at roughly a quarter new food, move to half around day three or four, three quarters by day six, and all new food by day seven. Dogs with a history of digestive trouble can take two to three weeks - there is no prize for finishing early.
Why does my dog have diarrhoea after changing food?
Usually because the change happened too fast. The gut microbiome adapts to a diet over time and needs a few days to adjust to a new one. Soft stools for two or three days during a transition are common and normal. Watery diarrhoea, blood, vomiting or a flat, unwell dog are not.
Can I switch dog food suddenly?
You can, and many dogs cope fine, but you are taking an unnecessary risk of several unpleasant days. The only time an immediate change is right is on veterinary advice - for example moving straight onto a prescription diet.
Do I need to transition between flavours of the same food?
Usually not, or only briefly. Flavours within one range typically share a base recipe, so the change is small. A couple of mixed meals is plenty for a sensitive dog.
How do I know the new food suits my dog?
Give it four to six weeks after the transition finishes, then look at stools, coat condition, energy, appetite and weight. Coat changes in particular take a full growth cycle to show - judging a food after one week tells you about the changeover, not the food.
This is label analysis, not veterinary advice - if your dog has a health condition, talk to your vet before switching foods.