The greatest threat to global health could possibly be man’s best friend. This is suggested by new research after multiresistant bacteria were found in dog food – which raised concerns about a possible international health crisis.
A new paper due to be presented at the European Congress on Clinical Microbiology and Infectious Diseases (ECCMID) warns that “the trend towards feeding dogs raw food could encourage the spread of antibiotic-resistant bacteria”.
Researchers from UCIBIO, Faculty of Pharmacy at the University of Porto in Portugal, examined various dog food samples from supermarkets and pet stores.
The study found that enterococci, a type of bacteria commonly found in the human intestine, were present in more than half of the samples analyzed.
The concern arises from the fact that these types of bacteria are often inherently resistant to antibiotics, meaning that some types of enterococci can lead to dangerous outbreaks. For example in the last two decades in the USA there were clusters of infections related to VRE (Vancomycin Resistant Enterococci) – often contracted first by a hospital.
An estimated 700,000 people worldwide die from drug-resistant infections each year. The UN states that this number could rise to 10 million by 2050 without adequate measures. Antibiotic resistance is classified according to of the World Health Organization (WHO) as one of the greatest threats to global public health.
“This study shows that dog food from international brands is a vehicle for clinically relevant enterococci that carry resistance to last-line antibiotics and relevant virulence genes, thus positioning pet food as an important source for the spread of antibiotic resistance,” says the paper, co – written by Dr. Ana Freitas, Dr. Carla Novais, Dr. Luísa Peixe and colleagues from UCIBIO.
Dr. Freitas and her team examined 55 dog food samples (22 wet foods, 14 raw frozen foods, 8 dry foods, 7 treats and 4 semi-wet foods) from 25 brands available in Portugal and the rest of Europe. The raw frozen foods included beef, goose, duck, salmon, turkey, chicken, lamb, and vegetables.
More than half (54 percent) have tested positive for enterococci, with 40 percent of this type of bacteria being resistant to multiple types of antibiotics. Almost a quarter were found to be resistant to linezolid, a drug that is considered the antibiotic of choice and is only used where other drugs cannot treat an infection. Resistance to this specific antibiotic is of particular concern.
The rise of raw dog food
Raw dog food, often sold in frozen chunks, has grown rapidly in popularity over the past five years. Data from Google shows a sharp increase in public searches for the product in 2020, particularly in the UK.
Owners believe that feeding their pets raw meat is healthier and claim to see improved dental health, increases in energy levels, and healthier fur and skin. However, some vets warn of household health risks and dogs with compromised immune systems.
The UCIBIO study found that multi-resistant enterococci were present in all of the analyzed raw-frozen samples – including linezolid-resistant bacteria. Only three of the non-raw samples contained multi-resistant enterococcal species.
The authors of the paper warn that with an estimated 90 million dogs in Europe, and nearly 500 million worldwide, dog food can be a dangerously overlooked source of antibiotic resistance worldwide.
“The close contact between humans and dogs and the commercialization of the brands examined in different countries pose an international risk to public health,” adds Dr. Freitas added.
“The European authorities need to raise awareness of the potential health risks involved in feeding raw food to pets, and the production of dog food, including ingredients selection and hygiene practices, needs to be reviewed.
“Dog owners should always wash their hands with soap and water immediately after handling pet food and after ingesting feces.”
