Prevalence and epizootiology of equine salmonellosis.

The article presents a study that aimed to determine the prevalence and spread of equine salmonellosis, a bacterial infection in horses. Researchers cultured feces from a sample of 1,451 horses across 13 months and found that 3.2% of these horses had salmonella in their feces, linking severe stresses such as abdominal surgery to severe cases of enteric salmonellosis.

Study Methodology and Findings

• The study involved collecting and culturing feces from 1,451 horses over a 13-month period. The researchers identified salmonella bacteria in these fecal samples to establish the frequency of equine salmonellosis.
• The study found that 46 horses, representing 3.2% of the sample, yielded one or more salmonella-positive fecal cultures. This provided a clear picture of the extent of salmonella infection in horses.
• Of notable interest were 20 horses that were found to excrete salmonella upon their admission. Five of these horses later developed severe diarrhea associated with enteric salmonellosis, hinting a possible link between stressful conditions like hospital admission and salmonella infection.

Associated Factors and Serotypes

• The study showed a strong association between severe stresses, particularly abdominal surgery, and an increased incidence of severe enteric salmonellosis.
• Various serotypes of salmonella were isolated from the analyzed feces. These included Salmonella agona, S anatum, S typhimurium, S typhimurium var copenhagen, S infantis, S montevideo, S meleagridis, S drypool, and an unnamed Salmonella serotype.
• The researchers found seven deaths attributable to four serotypes – S typhimurium, S anatum, S typhimurium var copenhagen, and S montevideo. This demonstrated the potential severity and mortality risk of salmonella infection in horses.

Seasonal Occurrence and Recommendations

• The study noted a distinct seasonal pattern in the occurrence of equine salmonellosis with the highest incidence in late summer to early fall and lowest in spring.
• The researchers also observed that horses could shed salmonella intermittently. They recommended a minimum of five consecutive negative fecal cultures before considering a horse not to be infected with salmonella. This recommendation serves as a diagnostic guideline for veterinarians and horse caregivers.