Salmonellosis in adult horses

There are very few infectious causes of diarrhoea in adult horses. The most common infectious causes of diarrhoea are Salmonella spp., intestinal parasitic worms, rotavirus and Clostridium spp. Of these causes, Salmonella is the most common (Astorga et al, 2004; Kolk and Kroeze, 2013).

Salmonella is a gram-negative facultative anaerobic bacterium. It can be found colonising the small intestine, cecum and colon of both cold- and warm-blooded animals. The most common strain in horses is Salmonella enterica serovar typhimurium. Other Salmonella species can also be found in horses, such as S. abortusequi sp. and S. enteriditis sp. Many strains of S. enterica are potentially zoonotic (Duijkeren et al, 2002; Astorga et al, 2004; Leon et al, 2018).

Horses have a greater susceptibility for salmonellosis while undergoing antibiotic treatment. Other risk factors are abdominal surgery, stress (for example as a result of transport or heat), concurrent disease and change of diet (Astorga et al, 2004; Kolk and Kroeze, 2013).