The scores
Hill’s Prescription Diet c/d Cat: B (76/100)
Hill’s Science Diet Cat: C (60/100)
A 16-point gap. c/d’s cleaner ingredient support tier and therapeutic mineral management earn the B grade.
How the ingredients compare
c/d Cat: Chicken, Whole Grain Corn, Corn Gluten Meal, Whole Grain Wheat, Brewers Rice
Science Diet Cat: Chicken, Whole Grain Wheat, Corn Gluten Meal, Chicken Fat, Corn Protein Meal
Both lead with chicken and include corn gluten meal. c/d uses whole grain corn and brewers rice; Science Diet uses corn protein meal and chicken fat higher in the list. Both are grain-heavy Hill’s formulas. The meaningful differences are in the therapeutic additions c/d includes: fish oil, potassium citrate, and precisely controlled mineral ratios.
Where Hill’s Prescription Diet c/d pulls ahead
Fish oil provides omega-3s that support bladder lining health. Potassium citrate manages urine pH to prevent calcium oxalate crystals. Controlled magnesium prevents struvite formation. DL-Methionine helps acidify urine when needed. c/d also includes chicken meal and egg product for more animal protein sources than Science Diet. The dual-crystal management (both struvite and calcium oxalate) is clinically validated — c/d can dissolve struvite stones in as little as 7 days. Shop on Amazon →
Where Hill’s Science Diet holds its own
Science Diet is less grain-heavy in the top positions, with chicken fat at four providing energy density. It costs less, is widely available without a prescription, and provides appropriate nutrition for healthy cats. Science Diet includes soybean oil and corn protein meal for additional fat and protein sources. For cats without urinary issues, Science Diet’s mineral levels are fine — the controlled mineral profile of c/d is only necessary for cats with crystal formation problems. Shop on Amazon →
The bottom line
Hill’s Prescription Diet c/d Cat (B/76) wins on ingredient quality over Science Diet Cat (C/60). The urinary health engineering — mineral control, pH management, and crystal dissolution capability — is the real value. If your cat has struvite or calcium oxalate issues, c/d is a well-validated choice. For healthy cats wanting better ingredients than Science Diet, Wellness Cat (B/80) or Nulo Cat (B/88) offer substantial upgrades.