Raw Pet Food Risks: Minerals and Pathogens Research

Raw Diet Pet Food Safety: New Research on Minerals and Pathogens

Choosing a diet for your pet involves balancing nutrition with safety. Two new studies highlight specific risks and regulatory challenges associated with raw meat-based diets (RMBDs). German research reveals how common pet food processing can mask the true level of added inorganic phosphorus, a mineral linked to adverse health effects. Simultaneously, a Portuguese study identified raw pet food as a reservoir for antibiotic-resistant Salmonella and E. coli, presenting a direct zoonotic threat.

Canning Alters Mineral Solubility, Masking Added Phosphates

Scientists at Ludwig-Maximilians-Universität München tested how heat processing changes phosphorus in pet food. They prepared 18 experimental cat diets, adding inorganic phosphate (Pi) from common supplements: phosphoric acid (H3PO4), monosodium phosphate (NaH2PO4·H2O), monopotassium phosphate (KH2PO4), and dicalcium phosphate (CaHPO4). One portion of each diet remained raw and frozen; the rest was canned.

The team used a method from Lineva et al. to measure phosphorus soluble in water after one minute (Psol1). In raw samples, the amount of Psol1 strongly correlated with added Pi. Canned versions of the exact same diets, however, showed a “strong decrease” in Psol1. Lead author Sophie Löffelmann and colleagues explain that heat denatures proteins in meat, binding phosphorus and making it less soluble. This creates a discrepancy: a canned food could contain high levels of added Pi, but lab tests would show low soluble phosphorus, obscuring the true additive content.

This matters because excess dietary phosphorus, particularly from highly soluble inorganic sources, is linked to renal stress and mineral imbalances. The EU does not require pet food labels to distinguish between natural organic phosphorus from meat and added inorganic phosphates. The study’s finding suggests the amount of added Pi in commercial pet food “is probably even higher than can be expected by measuring Psol1.” For more on mineral management in pet food, see our analysis on how processing alters mineral solubility.

Raw Diets Harbor Resistant Bacteria, Presenting Zoonotic Risk

A separate investigation in Portugal examined 79 samples of raw meat-based diets for pets, purchased from stores and online. The results, published in Eurosurveillance, are concerning: 53.2% contained multidrug-resistant Enterobacterales. Researchers isolated Salmonella in 12.7% of samples and pathogenic Escherichia coli in 41.8%.

Among the critical findings was the detection of E. coli carrying the mcr gene, which confers resistance to colistin, a last-resort antibiotic. Some bacterial clones, such as Salmonella 1,4,[5],12:i:- ST34 and E. coli ST162, are known to cause severe human infections. The study confirms these diets are a “neglected source” of exposure. Pets eating the food become colonized, shedding bacteria in their feces and spreading them in the home environment through contact and surfaces. This creates a direct pathway for human infection, a particular risk for children, the elderly, and those with weakened immune systems.

Maria Ribeiro-Almeida, Joana Mourão, and the research team stress that the presence of these clones in pet food reflects broader issues in the food chain and underscores a significant One Health threat. Managing infection risk requires more than just pet health vigilance; it intersects with broader home safety, similar to concerns raised about environmental toxins from household plants.

Balancing Nutritional Goals with Microbiological Safety

These studies present a dual challenge for pet owners considering raw diets. The first is nutritional transparency. The German study indicates that even with advanced testing, determining the exact source and quantity of minerals like phosphorus in processed food is complex. An owner seeking to precisely manage their pet’s mineral intake—perhaps for a condition like kidney disease—may face unreliable data. This complexity mirrors the careful balancing act required in formulating renal diets.

The second, more immediate challenge is pathogen control. The Portuguese study provides concrete evidence that a high percentage of commercial RMBDs contain dangerous bacteria. Freezing does not eliminate all pathogens, and routine handling—scooping, bowl cleaning, petting—becomes a vector for transmission. The risk is not theoretical; it is a measured, quantifiable hazard confirmed by microbial analysis.

Practical Steps for Safer Pet Feeding

Informed by this evidence, pet owners can take specific actions to mitigate risk. For those committed to a raw or lightly processed diet, treat the food as a potential biohazard. Use dedicated utensils and bowls, clean preparation surfaces with disinfectant immediately, and wash hands thoroughly. Keep the food frozen until use and thaw it in a sealed container in the refrigerator, away from human food.

Consult a veterinary nutritionist. They can help formulate a diet that meets AAFCO or FEDIAF nutritional standards while discussing strategies to manage microbiological risks, such as using high-pressure pasteurization (HPP). Be skeptical of marketing claims about “complete and balanced” raw diets without understanding the brand’s safety testing protocols for pathogens like Salmonella and E. coli.

Recognize that pets with health conditions, households with vulnerable people, or pets undergoing treatments like pain management for osteoarthritis that may involve immunosuppression, are at greater risk from zoonotic pathogens.

These studies move the conversation about raw diets beyond anecdote into the domain of measurable risk. They identify specific gaps in food labeling regulation and provide direct evidence of pathogenic contamination. Responsible pet care involves weighing the perceived benefits of any feeding strategy against these evidence-based safety and nutritional concerns.

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