Raw dog food a major source of antibiotic-resistant bacteria, researchers warn

PORTO, Portugal — Antibiotic-resistant bacteria has emerged as a major concern in recent years. Now, a troubling new report indicates that raw dog food on store shelves throughout Europe is a “major source” of these emerging strains of resilient germs. Study authors go so far as to call the problem an “international public health risk.”

Feeding pups raw dog food has become trendy in recent years due to its supposed benefits to canine health. While that’s all well and good from our pets’ perspectives, researchers say the very same multidrug-resistant bacteria in various raw dog foods are also popping up in human hospitals across several European nations.

On a global scale, estimates show that drug-resistant infections kill 700,000 people annually. By 2050, experts believe that figure will rise to 10 million deaths if health officials don’t take action to correct course. In fact, the World Health Organization considers antibiotic-resistant bacteria to be one of the biggest public health threats facing humanity today.

In an effort to better understand the role of raw dog food in all of this, researchers from the University of Porto analyzed various dog food items from supermarkets and pet shops. They looked specifically for the bacteria enterococci.

Enterococci actually live quite harmlessly within the stomachs of humans and animals. Unfortunately, if the bacteria makes its way to other areas of the body, it can result in severe infections.

Raw food contains the most harmful germs

In all, the team analyzed 55 samples of dog food (22 wet, 4 semi-wet, 8 dry, 7 treats, and 14 raw-frozen) from 25 different brands found throughout Europe. Those samples encompassed a variety of meats and ingredients including chicken, duck, salmon, vegetables, beef, lamb, goose, and turkey.

Results show 30 out of the 55 samples (55%) contained enterococci. Over 40 percent of those enterococci strains were resistant to a litany of antibiotics including erythromycin, tetracycline, quinupristin-dalfopristin, streptomycin, gentamicin, chloramphenicol, ampicillin, or ciprofloxacin. Another two percent of enterococci strains were resistant to vancomycin and teicoplanin and 23 percent were resistant to linezolid.

Researchers add that the large percentage of strains resistant to linezolid is especially concerning. Scientists consider linezolid as a “last-resort” antibiotic that is only used when other drugs have failed.

Moreover, all raw dog food samples contained multidrug-resistant enterococci (including linezolid resistance). On the other hand, only three analyzed non-raw samples contained multidrug-resistant bacteria.

Dog owners need to be especially aware of their hygiene

Further genetic sequencing work shows that some of the multi-drug resistant bacteria seen in raw dog food is identical to strains collected from human hospital patients in the United Kingdom, Germany, and the Netherlands. Scientists have also collected identical bacteria from farm animals and sewage in the U.K.

Another experiment entailed the research team transferring antibiotic resistance genes from dog food bacteria to other, experimental, bacteria. The fact that this was doable at all by researchers suggests it’s also quite possible within nature – which is another concerning sign.

In conclusion, study authors believe that dog food is a major source of antibiotic-resistant bacteria on a global scale.

“The close contact of humans with dogs and the commercialization of the studied brands in different countries poses an international public health risk,” says study co-author Dr. Ana R. Freitas in a media release. “European authorities must raise awareness about the potential health risks when feeding raw diets to pets and the manufacture of dog food, including ingredient selection and hygiene practices, must be reviewed. Dog owners should always wash their hands with soap and water right after handling pet food and after picking up feces.”

The study is published in the International Journal of Food Microbiology.