What was recalled
This page synthesizes the specific co-manufacturing relationship between Costco Kirkland Signature and Diamond Pet Foods, in the context of the broader Diamond co-manufacturing pattern covered at our Diamond Pet Foods co-manufacturing pattern page. Costco Wholesale Corporation launched Kirkland Signature as its house brand in 1995 and has expanded the brand across consumer categories steadily; the dry pet food line was added in the late 2000s as part of a broader pet category expansion at Costco warehouse locations. Diamond Pet Foods was selected as the co-manufacturer for Kirkland Signature dry pet food based on Diamond’s production capacity, geographic plant footprint (Diamond’s Meta, Missouri and Gaston, South Carolina plants serve different Costco distribution regions), and pricing competitiveness. The contract relationship has been in place continuously since approximately 2008, with annual production volumes scaling with Costco membership growth and pet category expansion.
The Kirkland Signature dry pet food product line spans dog and cat food across multiple formulas: (i) dog food — Adult Lamb & Rice, Adult Chicken & Vegetable, Adult Healthy Weight, Mature Adult, Puppy formulas; (ii) cat food — Adult Chicken & Rice, Adult Healthy Weight, Mature, Indoor formulas; (iii) Nature’s Domain — the grain-free and limited-ingredient line, also Diamond-produced, including Salmon Meal & Sweet Potato, Turkey Meal & Sweet Potato, Beef Meal & Sweet Potato, and Small Breed variants. The Nature’s Domain line is sold both at Costco warehouse locations and through Costco.com, while the Kirkland Signature dry pet food line is primarily warehouse-only with limited online availability. The formulas are nutritionally distinct from Diamond’s branded products despite shared manufacturing — specific recipes are formulated to Costco specifications.
The 2012 Salmonella Infantis recall affected Kirkland Signature dry dog food across multiple SKUs including specific lot codes of Adult Lamb & Rice, Adult Chicken & Vegetable, Mature Adult, and Puppy formulas. The recall press release surfaced the Diamond manufacturing relationship for many Costco customers who had not previously been aware that Kirkland Signature pet food was produced by Diamond. Costco issued direct customer notifications through membership records (cross-referencing pet food purchases to member accounts) and conducted in-warehouse recall communications. The 2012 event is the most-prominent surfacing of the Diamond co-manufacturing relationship in the Kirkland Signature brand history.
Why it was recalled
The structural concerns mirror the broader Diamond co-manufacturing pattern with Kirkland-Signature-specific amplification. Layer one — Kirkland Signature is the highest-volume single private-label customer of Diamond Pet Foods: the production volume of Kirkland Signature dry pet food at Diamond’s plants represents a substantial fraction of Diamond’s overall private-label co-manufacturing output. The single largest co-manufacturing contract carries the largest concentrated recall exposure when the manufacturer experiences a plant event. The 2012 Salmonella Infantis event affected Kirkland Signature substantially because the production volume was so high.
Layer two — the Costco brand trust signal does not transfer cleanly across the co-manufacturer: Costco enjoys among the strongest US retailer trust ratings (consistently top-3 in American Customer Satisfaction Index rankings for general merchandise retailers, behind only certain specialty retailers); the Kirkland Signature brand inherits this trust signal at the retailer level. The Diamond Pet Foods manufacturing relationship carries a different trust signal — Diamond has experienced multiple Class I recall events and is not a top-tier safety-track-record manufacturer. The retailer-brand trust signal and the actual manufacturer trust signal point in different directions; the consumer-facing tier surfaces the retailer signal but not the manufacturer signal.
Layer three — Costco’s recall response is exemplary even when the underlying co-manufacturer event is not: Costco’s 2012 Salmonella recall response was widely regarded as one of the strongest in the industry — direct member notifications via membership database cross-reference, in-warehouse recall communications, full purchase refund without proof of opened bag, and proactive transparency in customer communications. The Costco recall response framework partially offsets the Diamond co-manufacturer recall risk by ensuring affected customers are notified promptly and refunded fully. The framework is not a substitute for upstream contamination prevention but does mitigate consumer-facing recall-detection latency.
Health risks for your pet
The direct health risks for pets eating Kirkland Signature dry pet food are identical to the direct health risks for pets eating Diamond-branded dry pet food — the products come from the same plants, share production line equipment, and source ingredients through shared supply chains. The Kirkland Signature rubric grade is generally comparable to similarly-formulated Diamond Naturals products at the per-formula tier; the relevant rubric grades are documented at our Kirkland Signature dog food review and related comparison pages.
The indirect recall-risk exposure is the structural concern: a Diamond plant contamination event will typically affect Kirkland Signature alongside Diamond-branded products, and consumers who deliberately chose Kirkland Signature for the Costco trust signal may discover that the underlying supply chain risk is the same as for Diamond-branded products. Costco’s recall response framework mitigates the post-event consumer impact but does not prevent the pre-event supply chain exposure.
What to do if you bought affected product
Pet owners selecting Kirkland Signature dry pet food can navigate the framework meaningfully through several practical approaches: (1) recognize that Kirkland Signature dry pet food is produced by Diamond Pet Foods — the relationship has been in place since approximately 2008; the underlying manufacturer’s safety record (including the 2012 Salmonella event and 2005 aflatoxin event) applies to Kirkland Signature equally; (2) weigh the substantial price advantage of Kirkland Signature against the shared supply chain risk — Kirkland Signature dry pet food typically prices at 30-50% below equivalent-rubric branded products, which is real value; the tradeoff is exposure to Diamond-plant contamination events; (3) rotate across food formats and manufacturers for true supply chain diversification — if you feed primarily Kirkland Signature dry, occasional rotation through a different-manufacturer dry kibble (Champion Pet Foods, Hill’s Pet Nutrition, Royal Canin, Purina Pro Plan from owned plants) or a different food format (canned, freeze-dried, gently cooked) reduces concentrated supply chain exposure; (4) register your Costco membership for direct recall notifications — Costco’s recall response framework cross-references purchase history to membership records and delivers direct customer notifications; this is among the strongest retailer recall response systems in the US and partially offsets the Diamond co-manufacturer recall risk; (5) understand the Nature’s Domain line is also Diamond-produced — the grain-free / limited-ingredient line at Costco shares the same co-manufacturing relationship; rotating between Kirkland Signature standard and Nature’s Domain does not diversify supply chain risk; (6) compare Kirkland Signature to Diamond Naturals for rubric-equivalent value — the rubric grades are similar; the price-per-pound is often comparable; the choice typically comes down to retailer convenience and warehouse vs farm-feed-store shopping preference; (7) monitor Diamond Pet Foods specifically for recall press releases — not just Costco, not just Kirkland Signature: a Diamond plant event will surface across multiple downstream brands; tracking the underlying manufacturer catches risk earlier than tracking only the retailer brand.
How this affects KibbleIQ’s grade
The KibbleIQ rubric v15 grades Kirkland Signature dry pet food formulas per our published methodology — see our Kirkland Signature dog food review for the current rubric grades by formula. The co-manufacturing relationship with Diamond Pet Foods does not directly affect the rubric grade (which is ingredient and nutrient-profile driven), but is materially relevant to the supply chain trust framework. The Kirkland Signature dry pet food rubric grades are generally comparable to Diamond Naturals at similar price points, which is consistent with shared manufacturing and broadly similar ingredient sourcing. The broader framework is covered across our Diamond Pet Foods co-manufacturing pattern, co-manufactured pet food quality control framework, and private-label pet food controversy pages. For now, our recommendation: read both our current Kirkland Signature Diamond Co-Manufacturing review AND this page when evaluating the brand.