When switching a dog’s food, it’s recommended that you do so gradually, because they tend to have sensitive digestion. If you switch too abruptly, it can be a shock to the digestive system and result in tummy upset / diarrhoea. Below is a rough guide to a 7-day switch. If you think your pooch needs longer to adjust, try following the same gradual reduction in ratios, but stretch this over 2-3 days each time.
Infographic from PetSmart