Salmonella spp. cause a multitude of diseases in horses, including diarrhea, abscesses, septicemia, and other ailments. Over 2,200 serotypes of salmonellae are known and can be identified at the National Veterinary Services Laboratories (NVSL) in Ames, Iowa. With the exception of S. typhi, which only affects humans, all other salmonellae are zoonotic, posing possible transmission from animals to people.

In a NVSL report for isolates serotyped from July 1, 2000-June 20, 2001, the most frequently isolated serotypes from the clinical cases, herd and flock monitoring, and meat inspection of all species were S. typhimurium, heidelberg, newport, agona, and kentucky; all have also been isolated from horses. From equine clinical cases reporting a primary or secondary Salmonella infection during this same time period, the most frequent serotypes recorded were S. agona (213), typhimurium (207), typhimurium var copenhagen (52), newport (211), and newington (54). Another 287 samples accounted for 44 serotypes.

The vast majority of horses that have died in Central Kentucky are submitted for necropsy at the University of Kentucky Livestock Disease Diagnostic Center. Any salmonellae isolates cultured are forwarded to NVSL for serotyping.

This surveillance has been ongoing since 1985, with the last report in the October 1996 Equine Disease Quarterly. From January 1990-June 1996, S. typhimurium was the predominant postmortem isolate, newport and thompson were other the next most common serotypes, and 29 other serotypes were cultured