Raw feeding and the bacteria nobody mentions

A raw diet, often labelled BARF for biologically appropriate raw food, is built on raw muscle meat, organ and raw meaty bone, sometimes with added vegetables. Most public discussion of raw feeding turns on its claimed benefits: shinier coats, cleaner teeth, better digestion. The part that rarely gets equal airtime is the one that has actually been measured. The reported benefits of raw diets remain largely unproven by controlled trials, while the microbiological risks are quantified and documented (Freeman et al., JAVMA, 2013; FDA, 2010-2012). That asymmetry, an unquantified benefit set against a measured risk, is central to the disagreement and is the most useful thing for an owner to understand. This article lays out the bacteria nobody mentions and what the evidence says about them.

Petipedia · Editorial team

General documentary information. For an individual animal, a veterinarian's advice takes precedence over any online content.

The asymmetry at the centre of the debate

The reference review by Freeman and colleagues found that the claimed health advantages of raw feeding are largely unproven by controlled trials, and the WSAVA states that there is no documented evidence of a health benefit (Freeman et al., JAVMA, 2013; WSAVA). That does not mean raw feeding harms every animal that eats it. It means the upside rests on observation and testimony rather than on the kind of controlled evidence that would let anyone weigh it confidently.

The downside, by contrast, has been tested directly. The key to the whole debate lies in the level of proof: a reported benefit is not a demonstrated one, while the microbiological risks have been counted. Honest decision-making compares a measured risk against an unmeasured benefit, and that is an uncomfortable comparison for the raw case.

What the FDA testing found

The most-cited measurement comes from a US Food and Drug Administration study run through its Center for Veterinary Medicine between 2010 and 2012. It tested 196 commercial raw pet food samples. About 8 per cent were positive for Salmonella, and about 16 per cent were positive for Listeria monocytogenes (FDA, 2010-2012). For comparison, conventional processed foods tested positive at rates under 0.5 per cent. Raw meats test positive for these pathogens far more often than processed foods, which is the expected result of skipping the heat step that extrusion provides.

These agents can sicken the animal eating the food, or turn it into an asymptomatic carrier that sheds bacteria in its stools without appearing ill. That second outcome is the one that reaches beyond the pet.

Alt text: "Bar chart showing salmonella and listeria positivity far higher in raw pet food than in conventional food."

The hazard that reaches the household

A worrying finding extends the concern past the animal. A study in the Journal of Antimicrobial Chemotherapy documented antibiotic-resistant Enterobacteriaceae in raw pet foods, raising a public-health concern that reaches well beyond the animal itself (PMC, 2019). A dog or cat that becomes an asymptomatic carrier can shed resistant bacteria into the home environment, where children, elderly people and immunocompromised household members are most vulnerable. Raw feeding is therefore not only a question of the pet's health but of the household's, which is why the food-safety framing matters as much as the nutritional one.

Raw meat can also carry parasites such as Toxoplasma, Echinococcus and Trichinella if it has not been frozen correctly, adding a second class of biological hazard to the bacterial one.

The bone problem

Raw meaty bones are promoted as a dental asset, and they do scrape teeth. But the WSAVA also records, for a bone share usually held near 10 per cent of the ration, dental fractures, perforations, constipation and digestive obstruction (WSAVA). A fractured tooth or a perforated gut is a surgical emergency, and the dental upside does not always offset that risk. Cooked bones are worse still, becoming brittle and splintering into sharp fragments, and must be avoided entirely. The bone, like the raw meat, carries a real benefit and a measured downside in the same package.

The nutritional balance question

The microbiological risk is the headline, but it is not the only documented concern, and a second one deserves a mention because it compounds the first. A raw diet, especially a home-assembled one, has to be nutritionally complete and balanced to support an animal over time, and assembling that balance from raw ingredients is harder than it looks. The calcium-to-phosphorus ratio, the trace minerals and the fat-soluble vitamins all have to fall within fairly narrow bands, and a diet built by intuition rather than formulation frequently misses them. The reference review found the claimed benefits of raw feeding largely unproven while noting that nutritional adequacy is a real and recurring problem in these diets (Freeman et al., JAVMA, 2013).

This matters because it changes the risk calculus. An owner weighing raw feeding is not only accepting a measured microbiological hazard; they are also taking on the task of nutritional balance that a complete commercial food handles automatically. A raw diet can in principle be formulated correctly, but doing so reliably requires the same nutritional expertise that goes into a good kibble, plus the food-safety discipline the raw format demands. The convenience and the safety floor that a complete, heat-treated food provides are precisely what the raw route gives up.

Why the benefit claims are hard to verify

It is worth being clear about why the benefits of raw feeding remain unproven rather than simply unmeasured. Many of the reported gains, a glossier coat, more energy, smaller stools, are real observations by owners, but they are difficult to attribute to the raw format itself. Switching to raw usually means switching to fresher ingredients, often higher fat, sometimes lower carbohydrate, and the owner who makes such a deliberate change is also watching the animal more closely. Any of those confounders could produce the observed improvement without the rawness being the cause.

This is exactly the kind of question controlled trials are built to settle, and the controlled trials have not been done at the scale needed to confirm a benefit (Freeman et al., JAVMA, 2013; WSAVA). So the asymmetry holds in a precise sense: the risks have been measured directly in laboratory testing of the food, while the benefits rest on observations tangled up with other changes. An honest account does not deny that some animals appear to thrive on raw; it simply notes that we cannot yet attribute that thriving to the raw format rather than to everything else that changes alongside it.

What the veterinary bodies conclude

The two largest veterinary organisations have taken clear positions. The WSAVA, which federates about 113 member associations representing more than 390,000 veterinarians, concludes that there is no documented evidence of a health benefit from raw diets while the risks are well established, and its nutrition committee recommends not feeding raw to dogs and cats (WSAVA). The American Veterinary Medical Association discourages feeding raw or undercooked animal protein because of the risk to human and animal health, a policy it revised in January 2024 to recognise validated pathogen-reduction methods such as high-pressure pasteurisation beyond cooking alone (AVMA, 2024). Pro-raw societies contest this reading, but the major bodies converge on caution.

Reducing risk if raw is fed anyway

This is a benefit-against-risk judgement, and some owners will still choose raw. For them, the documented risk can be lowered, though not eliminated:

• Use traceable sources and, where available, products that have undergone validated pathogen-reduction such as high-pressure pasteurisation (AVMA, 2024).
• Freeze meat correctly to address the parasite hazard, recognising that freezing does not reliably kill bacteria.
• Practise strict kitchen hygiene: separate utensils and surfaces, thorough hand-washing, and prompt cleaning of bowls.
• Keep vulnerable household members away from food preparation areas and from contact with the pet's mouth and stools.
• Avoid weight-bearing and cooked bones, and watch for the obstruction and fracture signs the WSAVA records.

These steps manage the hazard the FDA measured. They do not turn an unproven benefit into a proven one, and they do not remove the public-health concern entirely.

Commercial raw and the limits of regulation

Owners sometimes assume that buying a commercial raw product, rather than assembling one at home, removes the concern. The FDA testing argues otherwise: those positive samples were commercial products, which means the format itself carries the hazard regardless of who packed it (FDA, 2010-2012). Commercial production can improve consistency and, where validated pathogen-reduction such as high-pressure pasteurisation is used, can lower the bacterial load (AVMA, 2024). But a raw product that has not undergone such a step still skips the heat treatment that makes conventional food microbiologically stable, and that is the whole point of the format for many of its buyers.

This leaves an owner of a commercial raw food with the same hygiene obligations as one feeding home-prepared raw: careful handling, separate utensils and surfaces, thorough cleaning, and protection of vulnerable household members. The label may look reassuring, but unless it specifies a validated pathogen-reduction process, the precautions do not relax. The honest framing is that commercial packaging addresses nutritional balance and consistency more than it addresses the microbiological risk, and the bacteria the testing found do not distinguish between a home kitchen and a factory pack.

Where to read more (feeding bacteria)

The questions on raw diet risks, household salmonella, bacterial shedding and the veterinary positions are handled in our raw, BARF and home-cooked diets FAQ and our choosing and judging quality FAQ. For structured help, the raw feeding food safety guide and the WSAVA and AVMA raw feeding position guide set out the precautions and the official stances. The principal pathogen is defined in our entry on salmonella.

Reframing the decision honestly

The point of laying out the bacteria is not to forbid raw feeding but to restore the missing half of the conversation. Most raw advocacy presents a list of benefits and is silent on the microbiological evidence, while the veterinary bodies present the risks and are accused of dismissing the benefits. A complete account holds both: the risks are real and quantified, the benefits are plausible to some owners but unproven by controlled trials, and the household dimension means the decision is not the pet owner's alone to bear the consequences of. That fuller picture is what an owner needs to make a genuine choice rather than a one-sided one.

Framed this way, the raw question stops being a clash of beliefs and becomes a weighing of evidence of different strengths. An owner who, after seeing the measured risk and the unproven benefit, still chooses raw can do so with eyes open and with the hygiene precautions in place. An owner who concludes that a complete, heat-treated food delivers the nutrition without the documented hazard has also reasoned well. What the evidence does not support is choosing raw in the belief that its safety is settled and its benefits are proven, because neither is true.

The takeaway (feeding bacteria)

The raw feeding debate usually skips its most concrete element: the microbiological risk. FDA testing found Salmonella in about 8 per cent and Listeria in about 16 per cent of commercial raw samples, against under half a per cent in conventional foods, and resistant bacteria have been documented that reach into the household. The claimed benefits, meanwhile, remain unproven by controlled trials. An owner choosing raw is weighing a measured risk against an unmeasured benefit, and that is the comparison the marketing rarely makes.