The scores
Royal Canin Shih Tzu: C (58/100) — Average. Brewers rice and brown rice lead, with chicken by-product meal at #3, chicken fat at #4, and oat groats at #5. Three grains dominate the formula.
Nutro: B (77/100) — Above average. Chicken as the first ingredient and chicken meal as the second, followed by whole brown rice, brewers rice, and split peas. Two animal proteins before any grain.
A 19-point gap pushes these into different grade tiers. Nutro’s protein-first approach delivers meaningfully different nutrition than Royal Canin’s grain-first formula.
How the ingredients compare
Royal Canin Shih Tzu: Brewers Rice, Brown Rice, Chicken By-Product Meal, Chicken Fat, Oat Groats
Nutro: Chicken, Chicken Meal, Whole Brown Rice, Brewers Rice, Split Peas
The contrast is clear at a glance. Nutro leads with whole chicken (fresh muscle meat) and chicken meal (concentrated protein), putting two animal protein sources in the top two positions. Royal Canin starts with two rice varieties, followed by chicken by-product meal at #3 — a generic by-product category rather than named meat.
Nutro also uses whole brown rice rather than processed brewers rice as its primary grain, and split peas add plant-based protein and fiber. Royal Canin’s inclusion of wheat gluten further down the list adds another concern for Shih Tzus with food sensitivities.
Where Nutro pulls ahead
Real chicken first: Whole chicken as ingredient #1 means fresh muscle meat is the most abundant component. Chicken meal at #2 adds concentrated protein. Together, they provide significantly more digestible animal protein than Royal Canin’s single by-product meal source at position #3.
No by-products, no wheat gluten: Nutro avoids chicken by-product meal and wheat gluten entirely. Shih Tzus are prone to food allergies and skin reactions, and common allergens like wheat can trigger chronic itching, tear staining, and digestive upset. Nutro’s cleaner ingredient list reduces allergen exposure.
Natural fiber from whole foods: Split peas provide natural fiber and plant protein, while Royal Canin relies on powdered cellulose (wood pulp) for its fiber content. The difference in fiber source quality reflects the broader ingredient philosophy gap between these two brands. Shop on Amazon →
Where Royal Canin Shih Tzu holds its own
The Shih Tzu formula includes GLA safflower oil, which supports skin and coat health — important for a breed with a long, flowing coat that requires significant maintenance. L-tyrosine supports skin pigmentation, and fish oil provides omega-3 fatty acids. These breed-relevant additions address real Shih Tzu needs.
Fructooligosaccharides serve as a prebiotic for digestive health, and glucosamine and chondroitin support joints. The kibble shape is designed for a Shih Tzu’s flat face and small jaw. These targeted features are genuine differentiators that Nutro’s general-purpose formula doesn’t offer.
Royal Canin’s veterinary research backing also carries weight. If your Shih Tzu has specific health issues and your vet has recommended this formula, that recommendation has clinical context behind it. Shop on Amazon →
The bottom line
Nutro delivers better base ingredient quality — real chicken first, no by-products, no wheat gluten — at B/77 vs C/58. For most Shih Tzu owners, the cleaner ingredient profile is the better choice, especially for a breed prone to allergies and skin sensitivities.
Royal Canin Shih Tzu’s GLA safflower oil and breed-specific kibble are nice touches, but they don’t overcome a grain-first, by-product-based formula. Read our full reviews of Royal Canin Shih Tzu and Nutro for the complete ingredient breakdown.