Kirkland Signature scores in the lower-mid tier on Chowmark. Costco's private-label pet food brand, Kirkland Signature pet food is manufactured by Diamond Pet Foods (Schell & Kampeter) — the same company that makes Diamond Naturals and Taste of the Wild.
The brand has recorded one lifetime recall, and it is directly tied to one of the most significant pet food safety incidents of the past two decades. In 2012, seven specific Kirkland Signature formulas were directly named in the Diamond Pet Foods Salmonella recall: Kirkland Signature Super Premium Adult Dog Lamb, Rice & Vegetable Formula; Adult Dog Chicken, Rice & Vegetable Formula; Mature Dog Chicken, Rice & Egg Formula; Healthy Weight Dog Formula; Maintenance Cat Chicken & Rice Formula; Healthy Weight Cat Formula; and Nature's Domain Salmon Meal & Sweet Potato Formula for Dogs. The recall affected products distributed across the US and Canada. The 2012 Diamond Pet Foods Salmonella outbreak infected at least 16 humans across 9 states, with 5 hospitalisations. A class-action lawsuit (Marciano v. Schell & Kampeter, Inc., Case No. 12-cv-2708, Eastern District of New York) alleged that a dog named Benji died after consuming recalled Kirkland Signature Nature's Domain food.
Kirkland Signature does not meet WSAVA Global Nutrition Guidelines. The brand does not publish peer-reviewed research and does not publicly employ a board-certified veterinary nutritionist. Formulas are AAFCO-compliant.
What Kirkland Signature does well: value. The price-per-pound is among the best in the category for the ingredient quality offered. Real meat as the first ingredient, no artificial colours or preservatives, and Costco's supply chain discipline mean the product is consistently manufactured. Diamond Pet Foods has invested in manufacturing improvements since 2012.
The bottom line: Kirkland Signature is a value-oriented pet food with a direct recall history from 2012 that every buyer should know. The Diamond Pet Foods manufacturing connection is the key context — if you are buying Kirkland, you are buying Diamond. The brand has a clean record since 2012, but the 2012 event is material.