A study published in Microorganisms has found that feeding pets raw pet food comes with a risk of pathogenic bacteria, including Shiga toxin-producing E. coli (STEC), which can cause serious illness in humans and is a public health issue. The study evaluated commercially available raw meat-based diets (RMBDs) in Switzerland.
These foods are made of uncooked raw muscle meats, organ meats, and the meaty bones of livestock or wild animals. They are mostly from the by-products of animals that are slaughtered for human consumption. The study looked at the occurrence of STEC isolated from commercially available raw pet food in Switzerland. In a recent study in the U.S., Shiga toxin-producing E. coli bacteria were identified in 4% of commercially available RMBDs.
Studies demonstrating the occurrence of STEC in RMBDs are rare, even though worldwide STEC causes about 2.8 million acute illnesses and almost 4,000 HUS cases every year. Most are associated with eating undercooked or raw meat, person to person transmission, or contact with animals or their environment.
The scientists found that of 59 samples, 59% tested positive by real-time PCR for the presence of Shiga Toxin genes stx1 and/or stx2, the two most potent Shiga toxins the pathogen produces. In addition, STECs were recovered from 41% of the 59 samples.
The strains were subjected to serotyping and virulence gene profiling, using whole genome sequencing. Of 28 strains, 29% carried stx2a or stx2d, which are linked to STEC with high pathogenic potential.
In all, 20 different serotypes were identified in the food, including “STEC O26:H11, O91:H10, O91:H14, O145:H28, O146:H21, and O146:H28, which are within the most common non-O157 serogroups associated with human STEC-related illnesses worldwide.”
In addition, STEC has a very low infectious dose number, only about 10 cells, so the potential for severe illness is high. The authors concluded that “the high occurrence of STEC in RMBDs poses an important health risk for persons handling raw pet food and persons with close contact to pets fed on RMBDs, and is of concern in the field of public health.”
STECs occur naturally in the guts of a variety of healthy wild and domestic animals and do contaminate meat during slaughter, evisceration, processing, and packing. The overall prevalence of STEC at 41% in this study is considerably higher than another study in the US, where just 4% of samples were contaminated. The authors state that comparative data is scarce, and discrepancies may be due to differences in testing methodologies. Still, the study does provide evidence that the occurrence of STEC in raw pet food may be underestimated.
The study provides more evidence for public health risks of feeding raw pet food to animals, and highlights the importance of promoting awareness of this issue among veterinarians, RMBD suppliers, and pet owners.
