CASE DESCRIPTION--In April 2012, Salmonella enterica serotype Infantis was detected in an unopened bag of dry dog food collected during routine retail surveillance. PulseNet, a national bacterial subtyping network, identified humans with Salmonella Infantis infection with the same genetic fingerprint as the dog food sample. CLINICAL FINDINGS--An outbreak investigation identified 53 ill humans infected with the outbreak strain during January 1 to July 5, 2012, in 21 states and 2 provinces in Canada; 20 (38%) were children ≤ 2 years old, and 12 of 37 (32%) were hospitalized. Of 21 ill people who remembered the dog food brand, 12 (57%) reported a brand produced at a plant in Gaston, SC. Traceback investigations also identified that plant. The outbreak strain was isolated from bags of dry dog food and fecal specimens obtained from dogs that lived with ill people and that ate the implicated dry dog food. TREATMENT AND OUTCOME--The plant was closed temporarily for cleaning and disinfection. Sixteen brands involving > 27,000 metric tons (> 30,000 tons) of dry dog and cat food were recalled. Thirty-one ill dogs linked to recalled products were reported through the FDA consumer complaint system. CLINICAL RELEVANCE-- A one-health collaborative effort on epidemiological, laboratory, and traceback investigations linked dry dog foods produced at a plant to illnesses in dogs and humans. More efforts are needed to increase awareness among pet owners, health-care professionals, and the pet food industry on the risk of illness in pets and their owners associated with dry pet foods and treats.