Quick Answer

Transition your cat to a renal diet over 7–10 days by gradually mixing the new food with the old one. This slow approach helps prevent food refusal and digestive upset.

Why a Gradual Transition Matters for Renal Diets

Renal diets like ROYAL CANIN® Renal Select are formulated with restricted phosphorus, calcium, and vitamin D to support kidney function. Cats can be sensitive to these changes in taste and texture. Rushing the switch often leads to fussy eating or vomiting. A slow introduction lets your pet adjust without stress.

When to Expect Acceptance or Resistance

Cats with chronic kidney disease can be picky due to nausea or changes in appetite. Some cats take to a new renal food in two days; others need up to two weeks. If your cat refuses the new food, try warming it slightly or mixing in a small amount of the previous food for longer. Never starve your cat into eating—this can worsen kidney function.

Step-by-Step Transition Protocol

  1. Step 1: Start Small – 25% New / 75% Old: Mix one part new renal food with three parts current food for days 1–2. Serve at room temperature to enhance smell. If your cat eats less than half, go back to a 10:90 ratio for two extra days.
  2. Step 2: Increase to 50/50 on Days 3–4: Offer equal parts new and old food. Watch for loose stools or vomiting. If digestion is normal, proceed to the next ratio. Cats with kidney issues may have sensitive stomachs; a day of 100% new food too soon can cause diarrhea.
  3. Step 3: Move to 75% New / 25% Old on Days 5–7: Most cats accept the new diet at this stage. Continue mixing to ensure complete acceptance. If your cat picks out the old kibble, crush the renal kibble slightly or mix with a bit of warm water to blend textures.
  4. Step 4: Offer 100% Renal Food by Day 8–10: Serve only the new renal diet. Your cat should be eating normally. If not, return to Step 3 for a few more days. Consult your veterinarian immediately if your cat stops eating for more than 24 hours—this is an emergency for CKD cats.

Renal Diet Product Examples

  • ROYAL CANIN Renal Select Adult Dry Cat Food: A complete dietetic dry feed formulated for chronic renal insufficiency and oxalate stone reduction, with restricted phosphorus, calcium, and vitamin D. Provides balanced nutrition while reducing the workload on your cat's kidneys—ideal for long-term daily feeding.

    ROYAL CANIN Renal Select Adult Dry Cat Food

    ROYAL CANIN Renal Select Adult Dry Cat Food

  • ROYAL CANIN® Veterinary Health Nutrition Renal with Fish 48s: Thin slices in gravy (wet food) with fish protein, designed for the same kidney support and restricted mineral levels. The gravy texture can appeal to cats who refuse dry kibble, and added moisture supports hydration—important for kidney health.

    ROYAL CANIN® Veterinary Health Nutrition Renal with Fish 48s

    ROYAL CANIN® Veterinary Health Nutrition Renal with Fish 48s