Fecal shedding of Salmonella spp by horses in the United States during 1998 and 1999 and detection of Salmonella spp in grain and concentrate sourceson equine operations

Objective-To estimate prevalence of fecal shedding of Salmonella spp among horses in the US horse population and prevalence of Salmonella sop in grain or other concentrate used as horse feed on equine operations in the United States. Design-Cross-sectional survey. Sample Population-Horses on 972 operations in 28 states. Procedure-Fecal samples were collected from horses resident at each operati on. Only a single sample was collected from any individual horse; number of horses from which samples were collected on each operation was determined an the basis of number of horses. on the operation. A single sample of grai n or concentrate was also collected from each operation. All samples were t ested for Salmonella spp by means of bacterial culture. Results-Overall. 0.8% (SE, 0.5) of resident horses shed Salmonella spp in t heir feces. The overall prevalence of operations positive for fecal sheddin g of Salmonella spp iie, operations with greater than or equal to 1 horse s hedding Salmonella spp in its feces) was 1.8% (SE, 0.7). Prevalence of grai n or other concentrate samples positive for Salmonella spp was 0.4%. Seroty pes of Salmonella spp that were identified in grain or other concentrate we re not those typically associated with clinical disease in horses. Conclusions and Clinical Relevance-Results suggest that the national preval ence of fecal shedding of Salmonella spp by horses in the United States was 0.8%, and that prevalence of Salmonella spp in grain or other concentrate used for horse feed was 0.4%.