How to Switch Your Pet's Food Without Upsetting Their Stomach

Most food-change diarrhoea is caused by speed, not by the new food itself. The gut bacteria need time to adjust.

The 7-day plan

Days 1–2: 75% old, 25% new. Days 3–4: half and half. Days 5–6: 25% old, 75% new. Day 7: all new. For a sensitive dog, stretch this to 14 days.

If loose stool appears

Go back one step and hold there for three days before advancing again.

When to move faster

Only on veterinary advice, for example when moving onto a prescription diet for an urgent problem.

Watch, do not assume

Persistent diarrhoea beyond a few days is not a transition problem. Get a faecal test rather than switching brands repeatedly.