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Brand Comparison · 2026

Blue Buffalo vs Kirkland Signature

Blue Buffalo (mid-premium kibble marketed on ingredient quality; partial WSAVA compliance) and Kirkland Signature (Costco's private-label dry food, reportedly made by Diamond Pet Foods, which meets 2 of WSAVA's 5 questions) compared head-to-head on WSAVA manufacturer-quality criteria, AAFCO substantiation, monthly cost, and which dog each is best for in 2026. Both brands meet 2 of 5 WSAVA criteria. Kirkland Signature is roughly 71% less than Blue Buffalo.

The verdict

Both meet 2 of 5 WSAVA questions, so the score does not decide this one. The price does. Kirkland Signature costs about $20 a month and Blue Buffalo costs $50-90. They lose points in different places. Blue Buffalo reports a full-time PhD nutritionist but owns only about 80% of its plants and uses a co-manufacturer. Kirkland Signature is reportedly made by Diamond Pet Foods, which runs seven US plants and a test-and-hold program, while Costco names no manufacturer, nutritionist or formulator.

Blue Buffalo fits an owner who values ingredient-list transparency and will pay up to $70 more a month for it. Kirkland Signature fits a Costco member who wants the lower cost and will confirm the manufacturer on the bag. If neither tradeoff appeals, Hill's Science Diet meets all 5 questions, though at $55-85/month. Ask your veterinarian about any dog with a medical condition.

Key differences at a glance

Quick comparison

DimensionBlue BuffaloKirkland Signature
Parent companyGeneral MillsCostco (reportedly made by Diamond Pet Foods)
CategoryBoutique dry kibbleMass-market dry kibble
WSAVA criteria met2 of 52 of 5
AAFCO substantiationFormulation onlyFormulation only
Full-time veterinary nutritionistYesPartial
Credentialed formulatorPartialPartial
AAFCO feeding trialsNoNo
Owns manufacturing plantsPartialYes
Quality control programYesYes
Typical monthly cost (50 lb dog)$50 – $90 / month$20 / month

General Mills

Blue Buffalo

Mid-premium kibble marketed on ingredient quality; partial WSAVA compliance.

Strengths

  • Strong consumer-facing ingredient transparency
  • Wide retail availability and brand recognition
  • Acquired by General Mills (2018) added scale and QC discipline

Watch-outs

  • Formulation-only substantiation (no feeding trials)
  • Does not own all manufacturing: reports owning about 80% of its plants and still uses a co-manufacturer
  • Caught up in past lawsuits over advertising claims
  • Named in 31 reports in the FDA's 2019 DCM update. The FDA did not establish that any food caused the disease

Best for: Owners who prioritize ingredient-list transparency over WSAVA manufacturer-quality criteria.

Avoid if: You specifically want a brand that meets all 5 WSAVA criteria.

Visit Blue Buffalo ↗

Costco (reportedly made by Diamond Pet Foods)

Kirkland Signature

Costco's private-label dry food, reportedly made by Diamond Pet Foods, which meets 2 of WSAVA's 5 questions.

Strengths

  • Low price, about $1 a pound for the 25 lb bag, or roughly $20 a month for a 50 lb dog
  • Diamond, the reported maker, publishes a test-and-hold program with certified-lab testing
  • Diamond operates seven US manufacturing facilities and is family-owned

Watch-outs

  • Costco's product page names no manufacturer. Costco's 2025 pet FAQ said Diamond makes the dry foods, but the bag's own maker line was not checked
  • Label says "formulated to meet" AAFCO profiles rather than citing feeding trials
  • No named nutritionist or formulator. Diamond describes only unnamed experts
  • Costco's Nature's Domain grain-free line was named in 29 reports in the FDA's 2019 DCM update. The FDA did not establish that any food caused the disease

Best for: Costco members who want a low-cost dry food and will check the bag's manufacturer line themselves.

Avoid if: You want a named, credentialed nutrition team or feeding-trial substantiation behind the food.

Visit Kirkland Signature ↗

Which is better for your dog?

The right pick depends on your individual dog. Blue Buffalo is the better choice when: Owners who prioritize ingredient-list transparency over WSAVA manufacturer-quality criteria. Kirkland Signature is the better choice when: Costco members who want a low-cost dry food and will check the bag's manufacturer line themselves.

On cost, Kirkland Signature is roughly 71% less than Blue Buffalo at the midpoint of typical premium spec for a 50 lb adult dog. On WSAVA manufacturer-quality criteria, both brands tie at 2 of 5.

Checking one brand rather than the pair? See is Blue Buffalo WSAVA-approved or is Kirkland Signature WSAVA-approved.

Where to buy

Made your pick?

Check current pricing on whichever brand fits your dog. Prices and promotions change frequently, so it is worth comparing both before you commit to a bag or a subscription.

Shop Blue Buffalo on Chewy →

Disclosure: these are affiliate links and IntelliBowl may earn a commission at no extra cost to you. Commission does not influence the comparison above. See our methodology.

Personalized recommendation

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Compare these brands against others

Methodology: WSAVA criteria reflect each brand's publicly documented manufacturer-quality practices as of October 2026, scored against the WSAVA Global Nutrition Committee's 5-question rubric. AAFCO substantiation reflects the dominant method used across the brand's main retail product line. Monthly cost reflects typical US 2026 retail for a 50 lb adult dog at premium spec, before autoship discounts. Recommendations are editorial and not influenced by affiliate relationships. See our recommendation methodology for IntelliBowl's quiz-engine ranking logic.