New research suggests raw frozen dog food contains bacteria that are resistant to key antibiotics.
The authors were due to present their work at the now canceled 2020 European Congress of Clinical Microbiology and Infectious Diseases (ECCMID).
Their work suggests that raw frozen dog food contains bacteria that are capable of resisting mainstream antibiotics.
This poses a risk of the transmission of these antibiotic resistant bacteria from dogs to humans, constituting an international public health risk, say the authors of the study.
According to the Centers for Disease Control and Prevention (CDC), “[a]ntibiotic resistance is one of the biggest public health challenges of our time.”
The CDC highlight that 35,000 people die after developing an antibiotic resistant infection each year in the United States.
The World Health Organization (WHO) describe antibiotic resistance as “one of the biggest threats to global health, food security, and development today.”
The WHO note that although bacteria can naturally become resistant to antibiotics over time, the misuse of antibiotics by humans is speeding the process up. This effect is happening either from the way we take antibiotics or from the way we use them in animal populations.
According to 2018 research in the journal Molecules, antibacterial resistance in animals has primarily developed due to people’s increasing demand for meat and dairy and the intensive farming that this requires.
To meet this demand, intensive agricultural practices have grown significantly. Due to the conditions under which farmers rear animals in intensive agriculture, the widespread use of antibiotics is necessary to maintain the health of livestock.
This practice increases the chances of bacteria developing antibiotic resistance, which can spread to humans in several ways.
In the research that the ECCMID was due to hear, the authors focused on another aspect of antibiotic resistance in animals: The possibility that raw frozen dog food may harbor antibiotic resistant bacteria.
According to a 2019 study in the Journal of Small Animal Practice, raw food diets for pets have grown in popularity in recent years. This is primarily due to what people perceive as the health benefits of animals consuming a more ‘natural’ diet and suspicion at processed pet foods. The study notes that there is little evidence to support the health benefits of such a diet that people often suggest.
In contrast, the same study notes that there is growing evidence that raw food pet diets may be dangerous for both animals and humans.
The authors concentrate on the risk that raw frozen dog food may pose to antibacterial resistance.
The authors took 46 samples of dog food — 22 wet, 15 dry, and nine raw frozen — from 24 international brands. They then cultured these samples and tested them with a range of antibiotics.
Different types of Enterococci bacteria appeared in 41% (19 out of 46) of the overall samples.
The scientists found these bacteria in 53% (8 out of 15) of the dry dog food and 9% (2 out of 22) of the wet dog food. However, they found them in all nine samples of the raw frozen dog food.
When the authors looked at the raw frozen samples in more detail, they found that they all carried bacteria that are resistant to many antibiotics, including standard antibiotics that healthcare professionals prescribe regularly. In contrast, drug resistant bacteria contaminated few samples of the wet or dry dog food.
For the authors of the study, “[t]he close contact of pets with humans and the commercialization of the studied brands in different EU countries pose an international public health risk if transmission of such strains occurs between dogs and humans.”
“There is strong past and recent evidence that dogs and humans share common multidrug resistant strains of Enterococci faecium, and, thus, the potential for these strains to be transmitted to humans from dogs.”
According to Dr. Ana Raquel Freitas from the Faculty of Pharmacy, University of Porto, Portugal, and an author of the study, “These raw frozen foods are supposed to be consumed after being thawed and could at least be cooked, to kill these drug resistant and other bacteria.”
“Although these foods seem to be regulated, regarding their microbiological safety by EU authorities, risk assessment of biological hazards should also include antibiotic resistant bacteria and/or genes besides only establishing the presence of bacterial pathogens, such as salmonella.”