INFLUENCE OF FECAL SHEDDING OF SALMONELLA ORGANISMS ON MORTALITY IN HOSPITALIZED HORSES

Objectives-To predict mortality of horses by use of clinical data from the first day of hospitalization, to determine whether fecal shedding of Salmonella organisms is related to severity of clinical disease, a nd to determine the impact of fecal shedding of Salmonella organisms o n mortality. Design-Prospective study. Animals-1,446 hospitalized hors es. Procedure-Medical information was obtained from horses hospitalize d in an intensive care unit or isolation facility during a 4.5-year pe riod. A model was created to predict mortality, using covariates deter mined on the day of admission. Predicted mortality provided a measure of clinical condition. Predicted mortality was compared between horses that were and were not shedding Salmonella organisms in their feces t o determine whether shedding was associated with severity of disease. Predicted and observed mortality between horses were also compared to evaluate the association between fecal shedding of Salmonella organism s and mortality. Results-92 horses were identified as shedding Salmone lla organisms. In a multivariable model, 4 variables (heart rate, resp iratory rate, rectal temperature, and clinical management) were associ ated with mortality. A higher predicted probability of death was obser ved in horses that shed Salmonella krefeld or more than 1 serotype. Re lative risk (RR) of mortality was high for horses shedding S typhimuri um (RR, 1.94; 95% confidence interval, 1.04 to 3.59) and multiple sero types (RR, 4.75; 95% confidence interval, 2.29 to 9.84). When the clin ical condition (ie, prior predicted probability of death) was taken in to consideration, fecal shedding of Salmonella organisms was not signi ficantly associated with mortality. Clinical Implications-In this hors e population, fecal shedding of S krefeld was associated with more sev ere clinical conditions at the time of admission; however, fecal shedd ing of Salmonella organisms during hospitalization did not alter predi cted mortality.