Describe Salmonellosis in horses.

• A. Rare in horses
• B. One of the most diagnosed infectious diarrheas in adult horses; subclinical carrier state around 3%; nosocomial pathogen in veterinary settings; common serovar Typhimurium
• C. Only Typhimurium causes disease
• D. Never causes septicemia

Answer: (B)

Salmonellosis in horses is best understood as a common infectious diarrhea in adult horses, with horses capable of becoming subclinical carriers that shed Salmonella in feces—even when they look well. About a small percentage (around 3%) of adults may carry the organism without signs, which means silent transmission can occur in groups, barns, and clinics. In veterinary settings, it behaves as a nosocomial pathogen because outbreaks can spread via contaminated stalls, equipment, and feeding areas, especially under stress or during outbreaks. The serovar Typhimurium is the one most frequently implicated in equine disease and outbreaks, making it the typical culprit you’ll hear about, although other serovars can also cause illness. It’s important to remember that Salmonella can cause septicemia in horses, particularly in foals or severely affected adults, so it isn’t confined to gastrointestinal signs alone.