Plan a 7–10 day transition to reduce digestive upset, especially for seniors. Start by mixing 75% old food with 25% new for 2–3 days, then move to 50/50 for 2–3 days, then 25/75 for 2–3 days, and finish at 100% new food if your dog stays stable.
During the switch, do simple daily checks:
• Stool monitoring: Track frequency and firmness. Mild softening for a day can happen; persistent diarrhea, mucus, or blood is a stop signal.
• Appetite monitoring: A brief dip can occur, but refusal to eat for more than a meal or two (or any signs of nausea) warrants pausing the transition.
• Weight monitoring: Weigh weekly (or every 3–4 days for small dogs). If weight is trending up or down unexpectedly, adjust portions based on the new food’s calorie density.
Stop the transition and consult your veterinarian if vomiting repeats, diarrhea lasts more than 24–48 hours, your dog seems lethargic, shows abdominal pain, or has a known condition (e.g., pancreatitis history) that makes diet changes higher risk.