Raw Pet Food Risks: Pathogens and Phosphates Safety Study

Raw Diet Pet Food Safety: A Dual Threat of Phosphates and Pathogens

Two recent studies offer new, concrete evidence about the risks associated with raw meat-based diets for pets. Research highlights a previously hidden issue with mineral additives in processed foods and confirms the significant pathogen load in raw products, creating a complex safety picture for owners to navigate.

How Heat Processing Masks Added Inorganic Phosphate

A team led by Sophie Löffelmann at Ludwig-Maximilians-Universität München investigated a specific, regulated risk in processed pet food. Excess dietary phosphate, particularly from inorganic additives like calcium phosphate (CaHPO4) or phosphoric acid (H3PO4), is linked to kidney stress and mineral imbalances. European Union regulations do not require manufacturers to declare the amount or use of these additives, making them a hidden component.

The researchers prepared experimental cat diets with known quantities of four common inorganic phosphate sources. They then measured “1-minute soluble phosphate” (Psol1), a marker for these highly soluble additives. In raw samples, the amount of Psol1 directly correlated with the added inorganic phosphate. However, when identical samples were canned using standard heat and pressure processing, the measurable Psol1 fraction dropped significantly.

“The findings indicate that the amount of added inorganic phosphate in commercial pet food is probably even higher than can be expected by measuring Psol1,” Löffelmann and colleagues write. The heat process changes the solubility of the additive, effectively concealing its true quantity from this particular analytical method. This matters because long-term consumption of high inorganic phosphate may quietly affect a pet’s health, particularly for animals with existing conditions like kidney disease.

Multidrug-Resistant Bacteria Are Common in Commercial Raw Food

While processing can alter minerals, it also eliminates pathogens—a step skipped in raw diets. A 2024 study published in Eurosurveillance provides sobering data on this front. Researchers from the University of Porto analyzed 79 samples of commercial raw meat-based diets for pets in Portugal, including frozen, freeze-dried, and pellet forms.

They found that 51.9% of the samples were contaminated with Enterobacteriaceae bacteria carrying resistance to critically important antibiotics. More alarmingly, 15.2% of samples contained Salmonella, and 1.3% contained pathogenic Escherichia coli harboring the mcr gene. This gene confers resistance to colistin, an antibiotic of last resort for treating severe multidrug-resistant infections in humans.

The study conclusively frames these products as a “neglected source of human exposure.” Handling the food, cleaning feeding bowls, or contact with a pet’s saliva or feces can transfer these bacteria. Pets themselves can become silent carriers or fall ill. This microbial risk stands in stark contrast to the concerns around processed minerals, representing an acute and direct threat to household health.

Weighing Nutritional Philosophy Against Microbial Reality

These studies force a difficult comparison between two different categories of risk. Proponents of raw diets often argue for the benefits of unprocessed, “natural” nutrition, suggesting it supports better gut health and microbiome diversity. The phosphate study indirectly supports the idea that processing changes food chemistry, sometimes in opaque ways that could have long-term health implications.

However, the pathogen study presents an immediate, evidence-backed danger. The high prevalence of resistant bacteria creates a tangible zoonotic pathway. The researchers identified specific, globally circulating Salmonella and E. coli clones in the food, meaning these are not random contaminants but established strains in the food production chain. Choosing a raw diet implicitly accepts this microbial risk for the pet and all household members, particularly the immunocompromised, elderly, or young children.

Applying Evidence to Feeding Decisions

For pet owners, navigating this information requires balancing philosophy with proven safety. If a raw diet is chosen despite the risks, stringent hygiene is non-negotiable: dedicated utensils and surfaces, immediate disinfection, and careful handwashing. Freezing does not eliminate all pathogens. Owners should source from companies that perform rigorous pathogen testing, though the Portuguese study shows contamination persists even in commercially prepared products.

For those feeding processed foods, the phosphate research underscores the importance of choosing reputable manufacturers committed to nutritional transparency. Diets formulated for specific life stages or health conditions, like those for cats with IBD or kidney disease, typically pay closer attention to mineral balance. The canning process, while altering phosphate solubility, provides the definitive benefit of pathogen elimination.

Both studies highlight that “natural” is not synonymous with safe, and “processed” is not inherently without nutritional compromise. The safest choice aligns with a pet’s individual health needs while minimizing preventable risks of infection and exposure to antibiotic-resistant bacteria.

Conclusion

Current evidence presents a dual challenge: processed foods may contain obscured mineral additives with potential long-term effects, while raw diets carry a high probability of contamination with dangerous bacteria. Informed feeding decisions must account for both the hidden chemistry of processing and the measurable microbiology of raw meat, prioritizing science over trend.

Sources:
https://pubmed.ncbi.nlm.nih.gov/41456310/
https://pubmed.ncbi.nlm.nih.gov/38699902/
https://pubmed.ncbi.nlm.nih.gov/37003096/