Methodology
How we decide what’s good for your dog.
Every score ChowScan displays is traceable. This page is the full rubric: the sources we use, how ingredients are graded, and how the final 0 to 100 score is built.
Sources
Five authoritative bodies. No blog posts.
FDA CVM (Center for Veterinary Medicine)
Pet food regulation, warning letters, compliance policies, Generally Recognized As Safe (GRAS) determinations.
AAFCO (Association of American Feed Control Officials)
Official ingredient definitions, nutrient profiles, and labeling standards used by most U.S. pet foods.
WHO / IARC (International Agency for Research on Cancer)
Carcinogen classifications (Groups 1, 2A, 2B) applied to additives, preservatives, and processing residues.
Tufts Cummings School of Veterinary Medicine
Petfoodology and clinical nutrition guidance from board-certified veterinary nutritionists.
Peer-reviewed veterinary journals
JAVMA, Journal of Animal Science, Veterinary Research Communications, and Frontiers in Veterinary Science for evidence on digestibility, bioavailability, and disease associations.
National Research Council — Nutrient Requirements of Dogs and Cats
Baseline for essential nutrient ranges, upper limits, and deficiency thresholds.
Ingredient grades
Three buckets. No hedging.
Named whole-food ingredients with clear nutritional benefit and no documented harm.
Deboned chicken, sweet potato, blueberries, fish oil, taurine.
Ingredients with incomplete labeling, mixed evidence, or marginal nutritional value.
Animal fat (unnamed source), caramel color, natural flavors.
Ingredients with documented harm, regulatory warnings, or IARC carcinogen classification.
BHA, BHT, ethoxyquin, artificial dyes (Red 40, Yellow 5/6).
Overall score
The 0–100 number, step by step.
Same rubric for every brand. Same modifiers, same caps, same clamp. No editorial weighting, no sponsorship adjustments.
- Step 01
Base score
75
Every product starts at 75 — a neutral baseline that assumes no obvious red flags and no standout positives.
- Step 02
Beneficial ingredients
up to +20
Named whole proteins, organ meats, omega sources, and clinically supported nutrients add points. Capped at +20 so a label can’t game the score by stuffing in trace vitamins.
- Step 03
Harmful ingredients
− varies
Penalties scale with severity — a single AVOID-grade preservative or banned dye can drop the score below 40. Multiple flags compound.
- Step 04
Protein-family dedup
—
We collapse same-source proteins (e.g. “chicken”, “chicken meal”, “chicken fat”) so a product can’t inflate its profile by listing the same animal three times.
- Step 05
Final clamp
0–100
After all modifiers, the score is clamped to a 0–100 range. Same rubric, same weighting, every product.
How we stay consistent
Same rubric for every brand.
The rubric above is the only thing that determines a ChowScan score. Every dog food and cat food runs through the exact same rating logic, the same ingredient grades, the same weighting, the same cutoffs.
When a rating changes, it’s because the underlying evidence changed. We publish a changelog on this page whenever a major update rolls out so you can see what moved and why.