Microbiological condition of bovine muscle tissues intended for raw-feeding of dogs

Introduction Feeding raw meats and slaughter by-products to dogs (`BARF') is often regarded as a 'natural' way of nutrition. Several studies provide evidence that such raw diets frequently contain pathogenic bacteria and thus could act as a source of infection not only for animals but also for humans handling such feedstuff. We present an investigation of the microbiological condition of frozen raw meat for feeding to dogs. Material and Methods In autumn 2018, 96 different products were purchased from 20 pet food shops in Vienna (one packaging unit per product). Samples were exclusively bovine muscle products. Eighty-nine samples could be assigned to ten manufacturers. Seven products were sold without labels. The products were assigned to the groups 'head meat' (n = 41), 'throat and neck meat' (n = 19) and 'other muscles' (n = 36). The samples were thawed overnight at +2 degrees C and examined by conventional cultural microbiological methods. Results The average aerobic mesophilic microbial count for the 96 samples was 7.6 +/- 1.1 log cfu/g. The average levels of Pseudomonas spp., lactic acid bacteria and co- agulase-negative staphylococci were 7.0 +/- 1.5 log cfu/g; 5.7 +/- 1.0 log cfu/g and 4.0 +/- 0.8 log cfu/g, respectively. Examination of the samples for Enterobacteriaceae and E. colt revealed mean values of 4.9 +/- 1.1 log cfu/g and 3.0 +/- 1.3 log cfu/g, respectively. The presence of pathogenic bacteria was assessed in 25 g aliquots. Salmonella spp. were detected in seven of the 96 samples (7.3 %): three isolates were S. Typhimurium and there was one isolate each of S. London, S. Senftenberg, S. Coeln and a monophasic isolate of group El. Five of the seven positive samples were from the group `head meat' and two from 'throat and neck meat'. Campylobacter spp. were not detected in any sample and Listeria monocytogenes was detected in ten of the 96 samples (10.4 %: five in 'head meat', four in 'other muscles' and one in 'throat and neck meat'). Conclusions Regulation (EC) No 142/2011 provides microbiological criteria for feed with respect to Enterobacteriaceae and Salmonella; these criteria are applicable during manufacture and storage prior to placing on the market. However, as the products were offered deep-frozen, we decided to apply the limits of the regulation for the evaluation of the samples. Seven of the 96 (7.3 %) samples did not meet the Salmonella criterion, and 82 of 96 (85.4 %) did not meet the Enterobacteriaceae criterion (<= 5000 cfu/g). Along with the general microbiological profile, there is a need for hygiene improvements for these products. Considering the increasing interest in BARF feeding in Europe, the role of raw pet food as a potential source of infection with human pathogens and implications for public health needs further investigation.

Veterinärmedizinische Universität Wien