The prevalence and epizootiology of salmonellosis among groups of horses in south east Queensland.

Over a 3-year period, 1178 faecal samples were cultured from 462 horses admitted to the equine clinic of the University of Queensland; 185 samples were positive for salmonella yielding 213 isolations consisting of 21 serotypes. S. anatum was the predominant serotype isolated (54%) followed by S. ohio (11.27%) and S. typhimurium (9.4%). One hundred and ten horses (23.81%) were positive on one or more occasion, and 42 (9.09%) on more than one occasion. S. anatum was the most common serotype isolated (71.43%) from the main drains in the stable block (33.57% positive samples). The prevalence of salmonella excretors among a large non-clinic population of horses in south east Queensland was 1.65%. Acute salmonellosis did not occur in the hospitalised animals. However, salmonellas were incriminated in 6 cases of chronic diarrhoea, which all yielded S. anatum, although the most severe involved both S. anatum and S. typhimurium, and these serotypes were isolated from multiple locations at the subsequent autopsy of 3 cases.