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New research suggests some raw meat pet foods contain alarmingly high levels of harmful bacteria.

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Want to put your dog on a raw meat diet? It could be dangerous for both of you

Few things will get a dog’s or cat’s sniffer going more quickly than the scent of raw meat. Grounded in the belief that feeding dogs and cats raw meat is more natural than giving them processed foods, pet owners appear to be increasingly seeking out raw meat–based diets. Yet, a new study suggests that could be a risky proposition, as the majority of commercially produced raw foods a research team examined contained high levels of harmful bacteria—including strains that could transmit diseases to pets and their owners alike.

Because dogs’ and cats’ wild ancestors ate raw meat almost exclusively, pet owners often believe their animals will benefit from such a diet, explains the study’s lead author, Magdalena Nüesch-Inderbinen, a microbiologist at the University of Zurich’s Institute for Food Safety and Hygiene in Switzerland.

Although some pet owners prepare their own raw meals with store-bought meat, the pet food industry has jumped wholeheartedly into the market, offering dozens of meal options. These foods usually contain uncooked muscle and organ byproducts of animals slaughtered for human consumption. Several cases of bacterial diseases in pets have been linked to such raw meat diets, but few studies have examined how widespread potentially harmful pathogens are in such commercial products.

To address that lack of data, Nüesch-Inderbinen and colleagues bought 51 different raw meat pet meals produced by eight different suppliers. (The authors declined to name the specific brands they tested.) The meat—including beef, chicken, horse, or lamb—came from either Switzerland or Germany. The scientists analyzed samples from each for the presence of enterobacteria, a family of bacteria that includes such harmful pathogens as Salmonella, Escherichia coli, and Shigella, as well as numerous harmless strains.

Nearly three-quarters (72.5%) of the samples had enterobacteria levels that exceeded regulations set by the European Union for pet food safety, the researchers report this week in Royal Society Open Science. Antibiotic-resistant strains of bacteria were identified in 63% of the samples. Salmonella, a highly transmissible pathogen that is one of the most common sources of food poisoning in both humans and pets, was found in 4% of the samples.

Together, the results suggest raw meat pet foods are far riskier than thought, Nüesch-Inderbinen says. She advises pet owners who buy these products to be extra thorough in washing their hands after handling the food and its packaging, and to be aware of the heightened risk of bacterial disease in their pets.

Scott Weese, a microbiologist at the University of Guelph’s Ontario Veterinary College in Canada, says the findings about antibiotic-resistant bacteria are especially concerning. “With Salmonella, the expectation is that if you get exposed, you either get sick or don’t in a short period of time,” he says. “With resistant bacteria that can live in the GI [gastrointestinal] tract for months or more, a pet or person could … potentially get a disease much later” if an initial course of antibiotics fails to kill the bug.

Dana Brooks, president and CEO of the Pet Food Institute, an industry group that represents most of the largest U.S. pet food manufacturers, acknowledged the danger that raw diets may pose to pets and their owners. “These bacteria may present a safety risk to your entire family, especially for vulnerable loved ones, such as children or the elderly,” she wrote in a statement to Science.

The lack of published scientific evidence for the health benefits of such raw meals seals the deal for Lisa Freeman, a veterinary nutritionist at the Cummings School of Veterinary Medicine at Tufts University in Grafton, Massachusetts. “I strongly recommend against feeding raw meat diets for the health of the pet, the owner, and the greater community.”