Switching Dog Food Without the Upset Stomach: Our 10-Day Plan
Most "my dog can't tolerate this food" stories aren't about the food. They're about the switch. Tip a dog straight from one kibble onto another overnight and a fair few will produce a garden you don't want to clean up — and the new food gets the blame.
When we moved Milo (12, Labrador × Lurcher, sensitive-ish stomach, strong opinions) onto a new dry food last year, we used the schedule below. Zero drama, and he was cleaning the bowl by day four. Here's the plan, plus the two mistakes we see most often.
The 10-day ratio schedule
The principle is boring and reliable: shift the old:new ratio slowly enough that the gut flora keeps up. Ten days is our default; stretch it towards fourteen for a dog with a known sensitive stomach (if that's your dog, our sensitive-stomach food guide is worth a read first).
- Days 1–3: 75% old food, 25% new — mixed in the same bowl, same mealtimes.
- Days 4–6: 50/50.
- Days 7–9: 25% old, 75% new.
- Day 10: 100% new food.
Hold at a stage for an extra couple of days if you see loose stools, and only move on once things firm up. One soft day is noise; three in a row means you're going too fast. If problems persist even at 25% new, the food itself may genuinely not suit — our guide on whether the food is causing the problem walks through how to tell.
Mistake 1: swapping the amount, not just the food
Foods differ hugely in calorie density. A cup of a 60%-meat food like Canagan carries far more calories than a cup of a budget kibble, so "same scoop as before" quietly becomes overfeeding — which produces exactly the loose stools people then blame on the recipe.
During a switch, work in grams, not scoops, and recalculate the daily total for the new food's feeding table. Our dog food calculator does the maths from your dog's weight and life stage, and the combined portion of old + new should add up to that figure — not to the old portion plus a bit.
Mistake 2: switching during other upheaval
Don't start a food transition the week you move house, put the dog in kennels, or change their routine. Stress affects a dog's gut just like ours, and you'll have no idea whether the food or the upheaval caused the fallout. Pick a boring fortnight. Boring is the goal.
Good landing spots
If you're switching because you want an upgrade rather than fleeing a problem, three foods we've reviewed make forgiving targets — all with named proteins and no artificial additives:
- Forthglade Natural Lifestage Chicken — cold-pressed, which in our experience is the gentlest format for transitions; the kibble breaks down quickly in the stomach rather than swelling.
- Harringtons Grain Free Turkey & Veg — the budget pick that doesn't behave like one; a sensible single-animal-protein recipe at about £2/kg.
- Canagan Free-Run Chicken — the step-up option at around 60% chicken; transition slowly, because the calorie density jump from a budget food is significant.
The full comparisons live in our grain-free roundup. If the switch you're weighing up is a change of format rather than brand — dry to wet, or a mix — read our wet vs dry comparison first, because the same 10-day schedule applies but the portion maths changes completely. And if you're only changing flavour within the same brand, there's a shortcut version of this plan in switching flavours without the full transition.
What "worked" looks like
By the end of the schedule you want: firm stools, normal enthusiasm at the bowl, no new scratching or ear trouble over the following month. That last one matters — genuine food sensitivities often show up in skin before gut, and on a lag. Mark a calendar note for four weeks out and actually look.
Milo's verdict on his new food, ten days in, was to sit under the food bin at 4pm instead of 5. We're counting that as a five-star review.
Some links above are Amazon affiliate links — as an Amazon Associate we earn from qualifying purchases, and it never affects which foods we recommend. If your dog has ongoing digestive problems, see your vet before changing diet.