Submitted to: Brazalian Archive of Medicine Veterinaria and Zootecnia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/7/2001
Publication Date: 4/20/2002
Citation: Losinger, W.C., Traub-Dargatz, J.L., Garber, L.P., Cray, P.J., Ladely, S.R., Ferris, K.E., Morgan, K. 2002. Factors associated with fecal shedding of salmonella spp by horses on us operations. Brazalian Archive of Medicine Veterinaria and Zootecnia.54(2):109-116. Interpretive Summary: Salmonella are bacteria that often cause food borne illness, particularly in the young, the elderly and those with diseases such as cancer and AIDS that compromise the immune system. However, Salmonella are ubiquitous in nature and most warm blooded animals can harbor Salmonella without causing illness, including horses. In turn, horses can pass these Salmonella to humans who may then become ill. We conducted a study to test for the presence of Salmonella in horses in the US. Additionally, we also examined factors that may have increased the likelihood that these horses harbored Salmonella. Fecal specimens were collected from 8,417 horses on 972 horse farms with > 3 horses in 28 states and cultured to test for the presence of Salmonella spp. Farms were characterized as Salmonella positive if at least one fecal specimen tested positive. Approximately 17 farms (1.8%) were positive for Salmonella. The odds of an operation being Salmonella positive increased as the number of resident horses increased. In addition, the following factors were found to be associated with increased odds of a farm being Salmonella positive: horses were used primarily for breeding; operation cleanliness was characterized as poor by the data collector; and new horses had been added to the farm without routine quarantine. These data are important for veterinarians, horse owners and those in the horse industry as they care and manage horse farms. Farms that use horses primarily for breeding should use optimal hygiene whenever possible as farms with poor cleanliness increased the risk of detecting Salmonella in horse feces. Ideally, all operations should isolate or quarantine new arrivals before adding these new horses to the resident horse herd.
Technical Abstract: In a cross-sectional national study that included 972 operations with > 3 horses on 1/1/98 in 28 states in the USA, 8,417 fecal specimens were collected from horses and cultured to test for the presence of Salmonella spp. Operations were characterized as Salmonella spp-positive if at least one fecal specimen tested positive for Salmonella spp. Percentages of Salmonella spp-positive operations were computed by management and other factors (collected from operation-level questionnaires) that were hypothesized to be related to fecal shedding of Salmonella spp. A logistic-regression model was constructed to identify factors associated with horses' shedding Salmonella spp in feces on an operation. The odds of an operation being Salmonella spp positive increased as the number of resident horses increased. In addition, the following factors were found to be associated with increased odds of an operation being Salmonella spp positive: horses were used primarily for breeding; operation cleanliness was characterized as poor by the data collector; and new resident equids had been added to the operation without routine quarantine.