Isolation of Salmonella organisms from the mesenteric lymph nodes of horses at necropsy.
OBJECTIVE
To determine the prevalence of Salmonella infections in horses at necropsy.


METHODS
Cross-sectional prevalence survey.


METHODS
102 horses.


METHODS
Mesenteric lymph nodes were collected from horses that were necropsied. Horses had died or were euthanatized because of severe disease or at the request of the owner. Twenty-eight of the horses were racehorses euthantized following acute catastrophic injuries on the racetrack. Mesenteric lymph nodes were submitted for Salmonella culture via direct plating of tissue specimens on MacConkey agar and by use of 4 enrichment culture techniques that used tetrathionate and selenite enrichment broth and brilliant green and Salmonella-Shigella selective plating media.


RESULTS
Salmonella typhimurium was isolated from the mesenteric lymph nodes of 2 foals (2/102, 1.96% of the horses). Salmonella organisms were not isolated from the mesenteric lymph nodes of adult horses.


CONCLUSIONS
Prevalence of Salmonella infections in horses of our study (1.96%) suggests that the results of cross-sectional surveys, using bacteriologic culture to determine prevalence of Salmonella infection, should be interpreted with caution. Prevalence of Salmonella infections determined in a single facility may not reflect the prevalence of Salmonella-infected horses in the general population; furthermore, obtaining a Salmonella isolate from a horse does not establish that the horse is a chronic Salmonella carrier.
House
J K
JK
Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis 95616, USA.
Smith
B P
BP
Wildman
T R
TR
Carrigan
M J
MJ
Kamiya
D Y
DY
D000372:Agglutination Tests / Q000662:veterinary; D000818:Animals; D003430:Cross-Sectional Studies; D005260:Female; D006734:Horse Diseases / Q000453:epidemiology*; D006736:Horses; D008198:Lymph Nodes / Q000382:microbiology*; D008297:Male; D008643:Mesentery; D015995:Prevalence; D012481:Salmonella Infections, Animal / Q000453:epidemiology*; D012486:Salmonella typhimurium / Q000302:isolation & purification*; D018038:Sodium Selenite / Q000737:chemistry; D013776:Tetrathionic Acid / Q000737:chemistry
D013776:Tetrathionic Acid; D018038:Sodium Selenite