Puppy feeding and growth
How do I switch my puppy to adult food without an upset stomach?
Last updated 23 September 2026 · How we write and check this
Short answer
Transition gradually over 7 to 10 days: start with about a quarter new food to three quarters old food, then move through half and half, then three quarters new to one quarter old, before feeding the new food alone. A faster switch is the most common cause of loose stools during a food change.
Why a slow changeover matters
A dog's gut bacteria adjust to whatever food it has been eating regularly, and a sudden change forces those bacteria to catch up quickly, which often shows up as soft stool or gas for a few days. Spreading the change over a week or more gives the gut time to adjust without much disruption.
A day by day outline
Days 1 to 2: roughly 25 percent new food, 75 percent old. Days 3 to 4: 50/50. Days 5 to 6: 75 percent new, 25 percent old. From day 7 onward: fully new food, assuming stools have stayed normal throughout each stage.
If stools stay loose despite going slowly
Pause the ratio at the last stage that produced firm stools for a few extra days before advancing further. If loose stools persist even at a slow pace, or if the puppy seems unwell, it is worth checking with a vet rather than continuing to push the switch through.
Key takeaways
- Transition to a new food gradually over about 7 to 10 days.
- A rough guide is 25, then 50, then 75 percent new food before going fully over.
- Pause at a stage longer if stools become loose before advancing further.
- Persistent digestive upset despite a slow transition is worth a vet check.