Epidemiologic study of salmonellae shedding in the feces of horses and potential risk factors for development of the infection in hospitalized horses.

A study was designed to identify epidemiologic factors associated with the development and spread of salmonellae in horses in a veterinary teaching hospital, through a case-control study and a longitudinal follow-up prospective study. In the case-control study, 44 horses shedding salmonellae in feces were compared with 99 control horses not shedding salmonellae in feces; regarding breed, sex, age and initial diagnosis, none of the odds ratios for study factors was significant. The factors found to be associated with fecal shedding of salmonellae in the prospective study included diarrhea at the time of admission to the hospital, fever while hospitalized, and a change in diet while hospitalized. Horses identified to be shedding salmonellae in feces were not limited to those with clinical signs of salmonellosis; however, spread of salmonellae from a shedder without clinical signs of disease to other hospitalized horses was not identified. The most common serovars of Salmonella isolated were oranienburg and newport.