Raw Pet Food Risks: A Research Update

Summary

Several new studies have been published that demonstrate the risk of bacterial, viral, and parasitic contamination of raw pet foods. A recently published study from Cornell University showed that live bacteria could be cultured from many raw cat foods, but no cooked cat foods. The raw cat foods also contained DNA from parasites and from bacteria that contained genes associated with antibiotic resistance, which indicates the potential that they could cause drug-resistance infections in people or pets. This study, like many others, highlights the animal and public health concerns of feeding raw meat pet foods, including freeze-dried and frozen products.

We’ve posted about potential risks from feeding raw meat to pets previously, but there have been a lot of new developments in the last few years that are worthy of a follow-up post. Probably the most news-worthy relates to a number of cats, both exotic and domestic, that have died in the last year due to H5N1 influenza (aka “bird flu”) obtained from raw poultry and/or raw milk in their diets, including several commercial raw cat foods. Cats who eat contaminated food have an extremely high fatality rate – greater than 50%! You can read more about this issue here: https://www.avma.org/news/feline-avian-influenza-cases-spark-concerns

Another rather chilling story involved a child who got infected with E. coli O157:H7, a very serious form of the bacteria that can cause kidney failure. Her infection was traced back to samples of a commercial raw frozen food fed to the family dog. Of particular concern is that the manufacturer refused to recall the diet after it was linked to her illness and in late September, the FDA issued another advisory, this time for Listeria and Salmonella in other products from the same manufacturer. Here are the  FDA notices: https://www.fda.gov/animal-veterinary/outbreaks-and-advisories/fda-advisory-do-not-feed-certain-lots-darwins-natural-pet-products-pet-food-due-e-coli-o157h7-and and https://www.fda.gov/animal-veterinary/outbreaks-and-advisories/fda-advisory-do-not-feed-two-lots-darwins-natural-pet-products-biologics-dog-food-due-salmonella-and

These and many other incidents as well as recent published studies highlight the persistent risk of bacterial, viral, and parasitic infections that raw pet foods can pose to both pets and people. The FDA investigated in 2011: https://www.fda.gov/animal-veterinary/animal-health-literacy/get-facts-raw-pet-food-diets-can-be-dangerous-you-and-your-pet and there have multiple university studies in the last few years assessing risk for contamination and antibiotic resistance with commercial raw diets. I was intrigued to see a new publication by a team from Cornell University in a journal called Communications Biology, which is part of the prestigious Nature journal family: https://www.nature.com/articles/s42003-025-08756-8

In the study, the researchers purchased 85 samples of commercial raw cat foods (28 refrigerated or frozen, 49 freeze-dried, and 8 in kibble form) along with 27 cooked cat foods (22 canned and 5 kibble). They then tested the foods for DNA from pathogenic bacteria and parasites, cultured the foods in petri dishes to see what grew, assessed for the presence of bacterial genes that could lead to antibiotic resistance, and also tested them for common pet food proteins to see if they matched their ingredient lists.

Here were their main findings:

1. Almost 18% (15/85) of samples contained animal proteins that were not present on the label, with chicken and turkey being the most common unreported components. Slightly more cooked cat foods had this issue than raw (9 vs 6) but that could have just been the luck of the sampling. This issue has been reported before in many studies and could be due to contamination with other proteins present in the facility or manufacturers intentionally (and illegally) swapping proteins. Either way, it can be an important issue for pets (or people) with food allergies.
   
2. The raw cat foods were more likely to contain DNA from pathogenic bacteria than cooked foods (the presence of DNA doesn’t mean that the bacteria are still alive or infectious, just that they were or are present).
   
3. Potentially dangerous bacteria could be grown from 42% of the raw cat foods but from none of the cooked cat foods. These bacteria included Salmonella enterica, E.coli, and Klebsiella. Viable bacteria were cultured from all forms of raw cat food but were most common in the frozen raw foods. Some of these bacterial strains were very genetically close to strains associated with human infections, including one Salmonella enterica strain that was identical to a reported human infection strain.
   
4. The raw cat foods contained more bacterial genes associated with antibiotic resistance than the cooked cat foods.
   
5. Parasite genes (but not necessarily live parasites) were found only in raw cat foods.

It’s not at all surprising that foods containing uncooked meat, eggs, or dairy products would have higher concentrations of bacteria and parasites, but one thing that wasn’t addressed in this paper is that some commercial raw pet food companies are using technology such as high-pressure pasteurization or processing (AKA “HPP”) to reduce bacterial and viral concentrations in raw foods to reduce pathogen risk. The authors of this study did not specify if any of the raw cat foods selected for this study utilized that technology, which could result in fewer positive tests for live bacteria and viruses.

While not a major finding of the study, another interesting thing was that all of the freeze-dried cat foods were confirmed to be raw when the manufacturers were contacted, yet only a “small minority” of the 49 freeze-dried products clearly stated on the label that they were raw. Many pet owners are unaware that most freeze-dried pet foods and treats are freeze-dried raw instead of freeze-dried after cooking and thus underestimate potential pet and human health risks from feeding these products. The lack of clear labeling makes it nearly impossible for pet owners to assess risk without contacting the manufacturers for each individual product. Until more accurate labeling is required or commonplace, it seems prudent to assume that all freeze-dried meat pet food or treats are raw until proven otherwise.

The take-home message from this study is that all forms of raw pet food and treats carry the risk of bacterial, viral, or parasitic contamination and that these infections can make dogs, cats, and even people very sick! 

Even worse, many of the bacterial strains found carry genes for antibiotic resistance. These genes not only cause problems for the animal eating the food and the people living with the animal but can also be transferred to other bacteria, thus increasing the risk of antibiotic resistance, which is already a serious concern in both human and veterinary medicine. Feeding cooked pet foods will reduce infection risk and reduce the risk of spreading antibiotic resistance genes in both pets and people.