Assesssing potential risk factors for microbiological contamination in raw meat-based diets for UK pet dogs

'Assesssing potential risk factors for microbiological contamination in raw meat-based diets for UK pet dogs: a reflection on owner storage practices and meat source' by Caitlin Marie Smithers, University of Chester.

Summarised by Katie Dubarry, Postdoctoral Research Fellow, University of Edinburgh

Raw meat-based diets (RMBDs) have gained in popularity among pet owners in recent years, but they come with microbiological risks that have the potential to affect both animal and human health. There is a lack of clear advice on RMBD storage for food safety, and other work has shown that some owners will refrigerate raw meat ‘leftovers’ for subsequent meals. This dissertation aimed to assess potential risk factors in RMBDs intended for pet dog consumption, by focusing on differing storage practices and their effects on meat from different commercially-available sources.


The research sourced beef and chicken RMBDs from 4 different UK companies. Total bacterial counts were measured at 3 time points: freshly thawed, after 24 hours of refrigeration, and after 48 hours of refrigeration. Samples were also cultured using selective media agar plates to allow the identification of bacterial species Escherichia coli, Salmonella spp., Shigella spp., Pseudomonas aeruginosa, and Enterobacteriaceae.


The study found that total bacterial counts increased significantly in the beef samples that had been refrigerated for 48 hours. However, there was not a significant increase after 24 hours. In the chicken samples no significant increase in bacterial counts was observed across the time points. However, the chicken samples had a higher baseline level of bacterial counts than the beef samples.


Bacterial cultures showed that many samples contained potentially harmful bacteria. 50% of samples contained E. coli, 37% contained Salmonella spp., 87.5% contained Shigella spp., and all samples contained Pseudomonas spp.
These findings have important implications for pet owners. The study highlights that storing thawed RMBDs in a refrigerator may not be safe, with highly pathogenic bacteria present in both beef and chicken products. The high bacterial counts, particularly in chicken, suggest that there is a risk of gastrointestinal illness due to the feeding and storage of RMBD. As storage may take place in the same refrigerator as food for human consumption cross-contamination is possible, placing a risk not only on pets but also to owners themselves.


This work represents an important piece of research in an unexplored area. This approach could be expanded in the future to increase sample size, sample type, and different storage facilities. If raw meat-based diets continue to increase in popularity it will become increasingly important to produce clear and uniform guidelines to prevent animal and human disease.