Most Raw Dog Food Contains Antibiotic-Resistant Bacteria

By Ronnie Cohen

July 16, 2021

(Reuters Health) - Popular raw-food dog diets could be helping to fuel the spread of antibiotic-resistant bacteria in humans, researchers say a new study suggests.

Investigators found enterococcus, an opportunist bacteria used as an indicator of antibiotic resistance, in a majority of 55 dog food samples purchased in Portugal.

Each of 14 frozen raw food samples had enterococcus and carried isolates resistant to at least one antibiotic, researchers report in the International Journal of Food Microbiology.

In addition, researchers were surprised to find antibiotic-resistant isolates to at least one antibiotic in six of eight samples of dry food, three of seven treats and three of 22 samples of wet food.

"Although the rate of resistant bacteria in processed samples was much lower, this was not expected, and authorities should review practices of manufacturing," said senior investigator Ana R. Freitas of UCIBIO, Faculdade de Farmácia, Universidade do Porto in Portugal.

But the findings came as no surprise to Ashlee Earl, a microbiologist who was not involved with the study.

"To microbiologists like me this is unsurprising," said Earl, senior leader of the bacterial genomics group at the Broad Institute in Cambridge, Massachusetts. "We know these organisms are ubiquitous."

"This is our reality," she told Reuters Health in a phone interview. "The best you can do is to be aware of it. Wash your hands; wash your cutting boards."

She also advised paying attention to the U.S. Centers for Disease Control and Prevention's guidance on pet food. (

The CDC recommends against feeding pets raw food. It advises pet owners to wash their hands with soap and water immediately after handling raw pet food and cleaning and disinfecting all surfaces that touched it.

The U.S. Food and Drug Administration also cautions: "raw pet food poses significant health risks to pets and pet owners." ( The FDA further recommends that pet owners wash their hands before feeding dogs and cats and washing food bowls and scooping utensils with soap and hot water after each use.

Antibiotic resistance threatens our ability to treat common infectious diseases and leads to higher medical costs, longer hospital stays and increased mortality. Drug-resistant infections kill an estimated 700,000 people a year, and as a result of the rising toll, the World Health Organization classifies antibiotic resistance as one of the greatest threats to global health and food security. (

In an email interview, Freitas said she and one of her co-authors both have dogs, and they feed them dry food. After the study, she said, they will look for dry food uncontaminated with antibiotic-resistant bacteria to feed them.

Earl does not live with a dog. If she did, she said, she would not change how she fed it as a result of the study.

"If I was feeding my dog raw food, I don't know that I would suddenly deprive my dog of raw food. It might make me think more about how I was handling it, but personally I wouldn't make a big change," she said.

"We know that farms tend to use a lot of antibiotics in growing their food," she said. "There's going to be bacteria in food that come into your house. The truth is our world is antibiotic saturated."

An estimated 70% of all medically important antibiotics in the U.S. are sold for use in animals, according to the Center for Infectious Disease Research at the University of Minnesota. (

SOURCE: International Journal of Food Microbiology, online July 10, 2021.