On March 18, an 8-year-old Arabian gelding in Carroll County, Maryland, was diagnosed with putative intestinal hyperammonemia secondary to salmonellosis. The gelding initially developed colic and fever on March 15 and was referred to a hospital for treatment and diagnostics. He remains hospitalized but is responding to medical management.EDCC Health Watch is an Equine Network marketing program that utilizes information from the Equine Disease Communication Center (EDCC) to create and disseminate verified equine disease reports. TheEDCCis an independent nonprofit organization that is supported by industry donations in order to provide open access to infectious disease information.About SalmonellosisSalmonellosis is a contagious and zoonotic bacterial infection caused bySalmonella spp, which causes enterocolitis. Clinically normal horses can transiently shed Salmonella, with shedding more common during:Concurrent illness: antibacterial usage, physiological disturbanceStress: transportation, social, nutritionalGastrointestinal disturbance: motility (especially colic), feed changeClinical signs of salmonellosis include diarrhea, fever, lethargy, anorexia, colic, localized infection, sepsis and septic shock. Foals are commonly more seriously affected with profound systemic illness, including hemorrhagic diarrhea, pneumonia, meningitis, inflammation of growth plate and septic arthritis.Treatment of the severe form of salmonellosis is based on IV fluid and electrolyte replacement and efforts to control the hosts responses initiated by the systemic inflammatory response.Prevention of salmonellosis is difficult, because the organism is present in the environment as well as in the feces of some healthy animals. Isolation and increased biosecurity are needed to prevent spread of the disease.