Among pets, cats face the greatest risks from highly pathogenic avian influenza (HPAI), and not just because they are biologically more susceptible to the disease than dogs. The risk to feral and outdoor cats comes directly from infected birds. However, even the most pampered indoor cat could be exposed to the disease through raw pet food that hasn’t been processed to neutralize disease-causing microbes. A literature review published in the Journal of Food Protection summarized current scientific evidence related to highly pathogenic avian influenza (HPAI) in raw meat pet foods and unpasteurized milk, including the disease’s epidemiology in companion animals, outbreak histories and the health implications for pets and people.
“By raising awareness among pet owners, industry stakeholders, and veterinarians, this paper highlights the immediate need for stringent surveillance and improved biosecurity in raw food supply chains to minimize viral transmission risks, thereby safeguarding pet health and curb the potential spillover to humans,” the study’s authors wrote.
The review compiled data from surveillance reports, experimental studies, outbreak investigations and regulatory sources. The authors detailed the biological mechanism of HPAI H5N1 transmission via raw pet food ingredients, including uncooked poultry meat, organ tissues, and raw milk from infected dairy cattle, and medically described the severe outcomes in infected pets.
The review documented multiple outbreaks among cats in the United States, Poland, South Korea and other places that were associated with the ingestion of HPAI-contaminated raw meat food. Felines appear particularly susceptible to the virus, with many developing systemic and neurological disease, often resulting in death. Recent U.S. cases, supported by genomic sequencing, have confirmed direct infection from raw cat food and milk products, prompting recalls and heightened regulatory scrutiny.
Notably for raw pet food manufacturers, the review emphasized the virus’ ability to remain viable after refrigeration and freezing. However, food isn’t the only way for cats and dogs to catch bird flu. The review authors cited experimental studies showing that both cats and dogs can contract HPAI H5N1 through respiratory exposure, with cats showing higher morbidity and mortality.
HPAI as a global disease risk
The paper also places these findings in a broader epidemiological context. It traces the evolution of the virus involved, the H5N1 clade 2.3.4.4b lineage. This variant has spread across continents since 2020, infecting wild birds, poultry, dairy cattle and a growing list of mammalian hosts. While pet-to-human transmission of HPAI H5N1 has not been confirmed, the review notes that close contact with infected animals, particularly in the context of raw food handling and pet care, presents a credible zoonotic risk, especially for immunocompromised individuals.
Importantly for the pet food industry, the review discussed regulatory implications, including recent Food and Drug Administration guidance requiring manufacturers to assess HPAI H5N1 hazards under the Food Safety Modernization Act. The paper suggests that companies producing raw pet food may need to implement enhanced controls, including testing, improved sanitation and pathogen-reduction technologies, to mitigate risk and avoid liability.
The review’s authors concluded by calling for continued research and surveillance at the human-animal interface, particularly as raw feeding practices grow in popularity despite the documented risks.
Raw chicken pet food risks reduced by lactic acid product during processing
Previous research may suggest means to provide raw meat-based pet foods to pet owners, despite the challenge to prevent microbial contamination while keeping the products raw. Without high temperatures to kill pathogens, such as H1N1 avian influenza, Salmonella, Escherichia coli and Listeria monocytogenes, raw pet foods need another means of inactivating potential threats to both pet and human health. Research published in the Journal of Food Protection explored how the combined use of high-pressure processing (HPP) and lactic acid fermentate (LAF), a carbohydrate fermentation product containing lactic acid, may mitigate these health risks from raw dog and cat foods.
High-Pressure Processing as a Pathogen Control Tool
HPP can achieve pathogen reduction in food products, including raw pet food. Previous research by the same team of scientists had already demonstrated that HPP effectively achieves a dramatic reduction of Salmonella spp., E. coli STEC and L. monocytogenes.
“Ingredients used in the different formulations can impact the effectiveness of HPP to deliver a 5-log reduction of pathogens and frozen storage can maintain the log reduction attained by HPP,” the scientists wrote in the Journal of Food Protection “However, E. coli STEC and L. monocytogenes were more HPP resistant than Salmonella spp. and their inactivation by HPP, especially in chicken formulation, can be inconsistent.”
Likewise, challenges remained in preventing the potential regrowth of L. monocytogenes during refrigerated storage.
To address these concerns in their study, the researchers inoculated chicken-based raw pet food with pathogen cocktails and treated the raw pet food with HPP at 586 MPa for durations of 2, 3 and 4 minutes. The effectiveness of HPP was enhanced through the addition of LAF applied at concentrations of 0.7% or 1.0% w/v. The products were stored frozen and monitored over a 21-day period.
Synergistic Effect of Lactic Acid Fermentate
The integration of LAF into the raw pet food formulation significantly improved pathogen inactivation. The study found that:
- Complete Pathogen Reduction: LAF at 1.0% combined with HPP resulted in complete inactivation of Salmonella spp., E. coli STEC and L. monocytogenes.
- Enhanced L. monocytogenes Control: Without LAF, a 4.02-log reduction was observed for L. monocytogenes with a 2-minute HPP hold time, which improved to 4.37-log with a 4-minute hold. Incorporating LAF eliminated the pathogen more effectively.
- Resilience of E. coli STEC: While E. coli STEC exhibited higher resistance to HPP compared to L. monocytogenes, the combination of HPP and 1.0% LAF achieved robust reductions.
Lactic acid disrupts bacterial cells. In acidic environments, undissociated lactic acid crosses bacterial membranes and dissociates within the cytoplasm, leading to acidification, impaired enzymatic functions and eventual cell death. Combined with HPP, which compromises membrane integrity, the synergistic effect results in unrepairable damage to microbial cells.
Operational Implications for the Pet Food Industry
This research highlights the practical applications of combining HPP and LAF for raw pet food manufacturers:
- Formulation and Process Control: The inclusion of LAF provides an additional safety barrier, reducing the reliance on prolonged HPP treatment and minimizing quality degradation.
- Shelf-Life Management: Products treated with HPP and LAF maintained microbial safety during frozen storage, supporting current best practices of frozen distribution and storage.
- Regulatory Compliance: The findings support the use of LAF as a preventive control measure within HACCP and food safety plans to meet stringent pathogen reduction targets.
The integration of lactic acid fermentation products with high-pressure processing may offer a scientifically validated method to enhance the microbiological safety of raw pet foods. As consumer demand for raw diets grows, these findings suggest a means for manufacturers to ensure safety without compromising product quality.
