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Research into multi-drug resistant Salmonella outbreak shows link to pet treats



Research into multi-drug resistant Salmonella outbreak shows link to pet treats

A new investigation into a multi-state outbreak of multidrug-resistant Salmonella infections linked to pig ear pet treats highlights the interconnectedness between human health and pet ownership, and emphasizes the need for close supervision of pet food products.

The research was funded by the Food and Drug Administration’s Animal Feed Regulatory Program Standards and the FDA’s Veterinary Laboratory Investigation and Response Network (Vet-LIRN).

From June 2015 to September 2019, 154 cases of Salmonella infection in humans were reported in 34 states. The study identified seven Salmonella serotypes that are genetically related to samples of pig ear treats. Whole genome sequencing (WGS) of isolates was used to predict antimicrobial resistance. It is striking that 107 of the 122 patients interviewed reported contact with dogs, and 65 of the 97 reported contact with dog treats. Salmonella was isolated from 137 pig ear treats, including imports from Argentina, Brazil and Colombia, and from four dogs. WGS predicted that 77 percent of human isolates and 43 percent of pig ear isolates were resistant to three or more antimicrobial classes.

Research findings

The study, published in the journal Lancet Public Health, investigates the first documented multi-state outbreak in the U.S. linked to pig ear treats. The investigation into the outbreak involved multiple agencies, including the CDC, FDA and state health departments, tracking down the sources of contaminated pig ear treats and evaluating their antimicrobial resistance profiles.

Pig treats and dogs were tested for Salmonella by government officials and the FDA. Products were traced to their country of origin where possible. Contaminated pig ear treats were found to be imported by three pet treat companies from South America, resulting in nationwide recalls by six suppliers.

Impact and implications for public health

The outbreak involved 154 human cases, with 107 patients reporting contact with dogs. The study found that both direct contact with pig ear treats and zoonotic transmission from dogs contributed to the spread of Salmonella. The study highlights the risk of contaminated treats for pets and the potential for such products to transmit antimicrobial-resistant bacteria to humans.

Regulatory and preventive measures

Pet treats like pig ears are regulated by the FDA under the Federal Food, Drug, and Cosmetic Act, which requires all animal foods to be safe, produced under sanitary conditions, and free of harmful substances. However, the study found that pathogen reduction efforts before and after processing were insufficient in this case.

The study also found that pig ear treats labeled as irradiated were still found to be contaminated with Salmonella. Irradiation is a method to reduce the pathogen load without heating the product. The effectiveness of irradiation on pet treats derived from dried animal byproducts, such as pig ear treats, has not been well studied.


The study highlights the need for more intensive surveillance of internationally traded pet food products for foodborne pathogens. It also calls on international manufacturers to strengthen strategies that reduce product contamination. Pet owners should be made aware of the disease risks associated with pig ear treats and take appropriate precautions, such as washing hands after handling pet food or treats.

The outbreak illustrates the widespread risk to pets and pet owners from contaminated pig ear treats. The study identified multiple Salmonella serotypes and antimicrobial resistance profiles, underscoring the need for coordinated mitigation efforts between state and federal agencies.

This outbreak of multidrug-resistant Salmonella linked to pig ear treats highlights the interconnectedness of human and animal health. It underlines the need for strict supervision and regulation of pet food products to prevent future outbreaks. Consumers should be aware of the potential health risks and take steps to protect themselves and their pets.

More information about this research and its findings can be found here found here.

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