The short answer: Hill’s Prescription Diet k/d Kidney Care (B/76) beats Hill’s Science Diet (C/61) by 15 points. The kidney diet actually has a cleaner ingredient profile than the standard retail food — by restricting protein, k/d avoids the cheap plant protein fillers (corn gluten meal, soybean meal) that drag Science Diet down. But k/d is a therapeutic diet for dogs with kidney disease. If your dog’s kidneys are healthy, the low protein content would be inappropriate.

The scores

Hill’s Prescription Diet k/d: B (76/100)

Hill’s Science Diet: C (61/100)

A 15-point gap that crosses the B/C grade boundary. k/d earns a B through cleaner ingredients and therapeutic supplements, while Science Diet sits in mid-C territory with its grain-and-filler-heavy formula.

How the ingredients compare

k/d: Brewers Rice, Chicken Fat, Brown Rice, Whole Grain Sorghum, Chicken

Science Diet: Chicken, Cracked Pearled Barley, Brown Rice, Brewers Rice, Whole Grain Wheat

k/d leads with rice and fat because the therapeutic goal is energy without protein. Science Diet leads with chicken. But the ingredient quality diverges sharply after the top five: k/d uses egg product, fish oil, FOS prebiotics, and betaine, while Science Diet loads up with corn gluten meal, soybean meal, and double palatability flavors.

Where Hill’s Prescription Diet k/d pulls ahead

k/d avoids corn gluten meal and soybean meal entirely — the cheap plant proteins that sink Science Diet’s score. Fish oil provides EPA/DHA omega-3s for kidney support. FOS prebiotics support gut health. Betaine aids kidney function. Egg product is a high-quality protein source. Whole grain sorghum is an ancient grain with a better nutritional profile than wheat. The formula includes four supplemental amino acids for a complete profile despite limited protein. Shop on Amazon →

Where Hill’s Science Diet holds its own

Science Diet starts with whole chicken at position one — a higher-quality protein lead than k/d’s brewers rice. It also provides more total protein, which is appropriate for healthy dogs. Science Diet is available without a prescription and costs less. For a healthy dog, Science Diet’s higher protein content is actually an advantage — k/d’s low protein would be nutritionally inadequate for dogs without kidney disease. Shop on Amazon →

The bottom line

Hill’s Prescription Diet k/d (B/76) wins on ingredient quality by 15 points over Science Diet (C/61). But this isn’t a choice you make based on ingredient scores — k/d is for dogs with diagnosed kidney disease, period. If your dog’s kidneys are healthy and you want better ingredients than Science Diet, look at Blue Buffalo (B/78) or Taste of the Wild (B/78) instead.