Recent study of bacterial and protozoal contamination of commercially available raw meat diets for dogs. Two hundred forty samples were obtained for analysis from 20 raw meat diets for dogs (containing beef, lamb, chicken, or turkey), as well as 24 samples from 2 dry dog foods, and 24 samples from 2 canned dog foods. Each product was purchased commercially on 4 dates approximately 2 months apart. Three samples from each product at each sampling period were evaluated via bacterial culture for non-type-specific Escherichia coli (NTSEC), Salmonella enterica, and Campylobacter spp. Anti-microbial susceptibility testing was performed on selected isolates. Polymerase chain reaction assays were used to detect DNA from Cryptosporidium spp., Neospora spp., and Toxoplasma spp. in samples obtained in the third and fourth sampling periods.

One hundred fifty-three of 288 (53%) samples were contaminated with NTSEC. Both raw and prepared foods contained NTSEC during at least 1 culture period. Salmonella enterica was recovered from 17 (5.9%) samples, all of which were raw meat products. Campylobacter spp. was not isolated from any samples. In 91 of 288 (31.6%) samples, there was no gram-negative bacterial growth before enrichment and in 48 of 288 (16.7%) samples, there was no aerobic bacterial growth before enrichment. Cryptosporidium spp. DNA was detected in 3 samples.

The authors concluded that bacterial contamination is common in commercially available raw meat diets, suggesting that there is a risk of foodborne illness in dogs fed these diets as well possible risk for humans associated with the dogs or their environments.

Evaluation of association between feeding raw meat and Salmonella enterica infections in a Greyhound breeding facility. The investigation was conducted at the request of a Greyhound breeder. One hundred and thirty-eight adult and juvenile dogs were studied. Observations regarding the environment and population of dogs were recorded. Fecal, food, and environmental specimens were collected and submitted for Salmonella culture. Isolates were serotyped and tested for susceptibility to 16 antimicrobials. Isolates underwent genetic analyses by use of pulsed-field gel electrophoresis and ribotyping.

Salmonella enterica was recovered from 88 of 133 (66%) samples of all types and from 57 of 61 (93%) fecal samples. Eighty-three (94.3%) of the isolates were serotype Newport, 77 (87.5%) of which had identical resistance phenotypes. Genetic evaluations suggested that several strains of Salmonella enterica existed at the facility, but there was a high degree of relatedness among many of the Newport isolates. Multiple strains of Salmonella enterica serotype Newport were recovered from raw meat fed on 1 day.

The authors concluded that Salmonella enterica infections and environmental contamination were common at this facility. A portion of the Salmonella strains detected on the premises was likely introduced via raw meat that was the primary dietary constituent. Some strains appeared to be widely disseminated in the population. Feeding meat that had not been cooked properly, particularly meat classified as unfit for human consumption, likely contributed to the infections in these dogs.

Examination of microbiological status of fresh cuts of beef. Samples of fresh beef (n = 1,022) were obtained from two processing plants in the Midwest from July–December 2003. They were analyzed for levels of microbial populations (total aerobic plate count, total coliform count, and Escherichia coli count) and for the presence or absence of E. coli O157:H7 and Salmonella spp. These samples yielded levels of 4.0–6.2, 1.1–1.8, and 0.8–1.0 log CFU/g for total aerobic plate count, total coliform count, and E. coli count, respectively. There did not appear to be substantial differences or obvious trends in bacterial populations on different cuts. Mean incidence rates of E. coli O157:H7 and Salmonella spp. on raw beef cuts were 0.3 and 2.2%, respectively. Of the total number of samples analyzed, cuts testing positive for E. coli O157:H7 included top sirloin butt (0.9%) and butt, ball tip (2.1%) and for Salmonella spp. included short loins (3.4%), strip loins (9.6%), rib eye roll (0.8%), shoulder clod (3.4%), and clod, top blade (1.8%). These data document the incidence of pathogens on whole muscle beef and raise the importance of such contamination of beef product that is mechanically tenderized. E. coli O157:H7 was exclusively isolated from cuts derived from the sirloin area of the carcass. Salmonella spp. were exclusively isolated from cuts derived from the chuck, rib, and loin areas of the carcass. Results of this study suggest that contamination of beef cuts may be influenced by the region of the carcass from which they are derived.

Another study of bacteriological evaluation of commercial canine and feline raw diets. Twenty-five commercial raw diets for dogs and cats were evaluated bacteriologically. Coliforms were present in all diets, ranging from 3.5 x 103- 9.4 x 106 CFU/g (mean 8.9 x 105; standard deviation 1.9 x 106). Escherichia coli was identified in 15/25 (64%) diets; however, E. coli O157 was not detected. Salmonella spp. were detected in 5/25 (20%) diets; 1 each of beef-, lamb-, quail-, chicken-, and ostrich-based diets. Spore forming bacteria were identified from 4/25 (16%) samples on direct culture and 25/25 (100%) samples using enrichment culture. Clostridium perfringens was identified in 5/25 (20%) samples. A toxigenic strain of Clostridium difficile was isolated from one turkey-based food. Staphylococcus aureus was isolated from 1/25 (4%) diets. Campylobacter spp. were not isolated from any of the diets.

The interpretation of routine laboratory tests (blood and urine profiles) on dogs fed raw food diets should take into account the differences expected for this cohort of animals in comparison to the normal reference ranges established from dogs fed standard cereal-based diets.

Significant contamination of commercial source raw meat diets fed to both dogs and cats was reported in several recent studies. In another unpublished account, a dog fed human grade raw ground pork developed muscle aches and fatigue and was found to have sarcocytosis. For people feeding raw meat diets to dogs and cats, the potential human health hazard from handling contaminated raw meats should be recognized, even if the relatively short gastrointestinal tract and food transit time of these animals usually prevents clinical infection. Furthermore, feeding raw meats to animals that are ill, especially those with bowel disease, should be discouraged.

References: Morley et al, JAVMA 228:1524-1532, 2006; Strohmeyer et al, JAVMA 228: 537-542, 2006; Stopforth et al, J Food Prot, 69:1456-1459, 2006; Dodds, Research Study Report for Heska Corp, 2005; Weese et al, Can Vet J 46:513-516, 2005; Wynn et al, AAVN Symp, June 2003 (abstr.); Antech News June 2003.