The scores
Purina Pro Plan: C (62/100) - Average. Chicken leads, but by-product meal and plant proteins fill in right behind it.
Royal Canin: C (58/100) - Below average. Brewers rice as the first ingredient makes this a grain-first dog food at a premium price.
How the ingredients compare
The top five ingredients tell you everything:
Purina Pro Plan: Chicken, Rice, Poultry By-Product Meal, Soybean Meal, Corn Protein Meal
Royal Canin: Brewers Rice, Chicken By-Product Meal, Oat Groats, Wheat, Corn Protein Meal
Pro Plan starts with an actual named animal protein. Royal Canin starts with brewers rice - a milling byproduct, essentially broken rice fragments. That's the single biggest difference. When a grain is the most abundant ingredient in your dog's food, the formula is built around carbohydrates, not protein.
Both brands lean on by-product meal and corn protein meal to hit their protein targets. Both use plant-based fillers where you'd want to see animal protein. The formula philosophies are similar - cost-optimized with functional supplements added on top - but Royal Canin takes it a step further by putting grain first.
Where Purina Pro Plan pulls ahead
Protein placement: Chicken as the first ingredient means animal protein is the most abundant component. That's a low bar, but Royal Canin can't clear it. When brewers rice leads your ingredient list, you're feeding your dog a grain-based food with protein supplements, not a protein-forward formula.
Fish oil: Pro Plan includes fish oil, providing omega-3 fatty acids for skin, coat, and joint health. This is a meaningful functional ingredient that Royal Canin's standard adult formulas don't emphasize as prominently.
Price-to-quality ratio: Pro Plan is generally cheaper than Royal Canin. Scoring a full letter grade higher while costing less makes it the clear value winner - even though neither brand represents good value compared to the broader market. Shop on Amazon →
Where Royal Canin holds its own
Royal Canin's breed-specific approach is genuinely innovative. Kibble shape, size, and nutrient ratios calibrated for specific breeds represent real research - not just marketing. If your vet prescribes a Royal Canin Veterinary Diet for a medical condition, that's a different product line and a different conversation entirely.
Royal Canin also includes FOS prebiotics for digestive health and chelated minerals for better nutrient absorption. These are quality functional ingredients. The problem is they're bolted onto a grain-first base formula that undermines the overall quality.
Both brands conduct extensive feeding trials with board-certified veterinary nutritionists, which is more than most competitors can claim. The science is real, even if the ingredient lists don't reflect it. Shop on Amazon →
The bottom line
This is a matchup between the two most vet-recommended brands in the industry - and neither one scores well. Purina Pro Plan's C grade beats Royal Canin's D, but the real takeaway is that "vet-recommended" doesn't mean "best ingredients." Both brands rely on by-products, plant proteins, and cost-conscious fillers. Pro Plan wins by starting with chicken instead of a grain, which is the bare minimum you should expect from a dog food.
If you're choosing between these two, Pro Plan is the better pick. But if you're open to looking beyond the vet-office display shelf, brands like Blue Buffalo, Taste of the Wild, and Diamond Naturals all score a B (78/100) at comparable or lower prices. Read our full reviews of Purina Pro Plan and Royal Canin for the complete breakdown.