Is Hill's Science Diet really the best dog food? An honest look at kibble vs fresh

Most US dogs and cats are now overweight, and most owner-found home recipes are nutritionally incomplete.1 So the food question matters. The trouble is that the loudest answers, on both sides, are more confident than the evidence.

No brand paid for inclusion here.

A popular vet recently summed up the conventional case on a podcast: premium brands like Hill’s Science Diet, Purina Pro Plan, and Royal Canin are better because they are big enough to fund research and run feeding studies. That instinct is reasonable. The leap from “well-researched and safe” to “best” is where it breaks down.

Here is the honest comparison.

What everyone actually agrees on

Start with the common ground, because it is solid.

A diet that is complete and balanced beats one that is not. That is the real, well-supported finding behind most food advice.1

The phrase “complete and balanced” is earned one of two ways: a food is formulated to meet an AAFCO nutrient profile, or it passes an AAFCO feeding trial.2 One note worth fixing: there is no such thing as “AAFCO certified.” AAFCO does not test, approve, or certify any pet food.2

So the question is not “kibble or fresh.” It is “is this diet complete and balanced, and who stands behind it.”

The two views

What the research actually says

On “best”: no large, long-term randomized trial shows that Hill’s, Purina, or Royal Canin produce better longevity or lower disease than a well-formulated fresh or home-cooked diet.1 The honest claim is the narrower one above.

On home cooking: the deficiency risk is real. In a 200-recipe analysis, only 9 met AAFCO minimums for every nutrient, and over 83% had multiple deficiencies. Most recipes were even written by vets.1 The fix is not “never home cook.” It is “use a recipe from a board-certified veterinary nutritionist.”

On grain-free: mostly marketing. Grain allergy is uncommon, and the top food allergens are proteins like beef, dairy, and chicken, not grains.7 The grain-free trend also backfired. The FDA is investigating a link between grain-free, legume-heavy diets and a heart condition called DCM. The association is real, but cause was never proven, and the FDA paused updates in late 2022.8 Do not read that as “grain-free causes heart disease,” and do not wave the signal away either.

On raw: the risks are well documented. Studies find Salmonella, Listeria, E. coli, drug-resistant bacteria, and parasites in raw products, and dogs can shed these pathogens.4 Freeze-drying lowers but does not remove the risk. The claimed benefits over a balanced cooked diet are not backed by strong, repeated evidence.4 If you want a fresh diet, cooking the meat keeps the nutrition. Cooking unfolds protein, it does not destroy the amino acids.9

On a few smaller points the conventional vet got right: by-products are nutritious organ parts, not hooves and feathers.10 Corn is not a “filler.”11 Large-breed puppies need controlled, not extra, calcium so their bones grow slowly.12

Plain risk comparison

Every option carries some risk.

• Vetted commercial kibble or fresh service: lowest risk of a nutrient gap. Open question on long-term processing effects.6
• Home cooking: high risk of an unbalanced recipe unless a nutritionist formulates it. Low risk once it is properly formulated and followed.1
• Raw: documented pathogen and drug-resistance risk, to dog and household, with no proven benefit over a balanced cooked diet.4

One claim to retire: the idea that a brand’s recalls are a good sign because it means strong quality control. A recall means a problem reached shelves. Most US pet-food recalls are voluntary, which does show a working safety process, but a recall is a correction, not a badge.13

Questions to ask your vet

• Does the maker of this food employ a qualified nutritionist, a PhD in animal nutrition or a board-certified veterinary nutritionist?
• Is this diet backed by AAFCO feeding trials, or only formulated to a profile on paper?
• If I want to cook at home, can you refer me to a board-certified veterinary nutritionist to formulate a complete recipe?
• For my large-breed puppy, does this food meet the large-breed growth calcium limit?
• Given my dog’s age, weight, and any conditions, what is the right portion and body condition target?

The bottom line: a vetted, complete diet is the safe default, and that is worth respecting. Just hold “best” to a higher bar than the marketing does, on both sides of the bowl.

Sources

1. Stockman, Fascetti, Kass, Larsen — Evaluation of recipes of home-prepared maintenance diets for dogs, JAVMA 2013 Tier 1 ↩
2. AAFCO — Understanding Pet Food (AAFCO does not test, approve, or certify) Tier 1 ↩
3. WSAVA Global Nutrition Committee — Selecting a Pet Food (2021) Tier 1 ↩
4. AVMA — Raw or Undercooked Animal-Source Protein policy (with van Bree 2018; Freeman 2013) Tier 1 ↩
5. The Farmers Dog — board-certified veterinary nutritionists on staff (the fresh-food camp is credentialed) Tier 2 ↩
6. Frontiers in Animal Science 2025 — Home-prepared dog food: the head-to-head evidence gap and processing open question Tier 1 ↩
7. Mueller, Olivry, Prelaud — Common food allergen sources in dogs, BMC Vet Res 2016 Tier 1 ↩
8. FDA — Q&A: FDA work on potential causes of non-hereditary DCM in dogs Tier 1 ↩
9. Tufts Petfoodology — Raw diets: a healthy choice or a raw deal? (cooking and protein) Tier 2 ↩
10. Tufts Petfoodology — By-products are nutritious organ parts Tier 2 ↩
11. Tufts Petfoodology — Corn is a nutritious ingredient, not a filler Tier 2 ↩
12. Purina Institute — Canine hip dysplasia and large-breed growth (controlled calcium) Tier 2 ↩
13. FDA — Recalls, Market Withdrawals and Safety Alerts (Animal and Veterinary) Tier 1 ↩