Salmonellosis
Learn what the condition is, how it may be detected early, how it is treated or managed, and which breeds or species are linked to it.
Condition snapshot
A concise guide to the condition’s pattern, detection, management and urgency.
Human-health precautions may applyFollow veterinary and public-health hygiene advice, especially for higher-risk household members.
Limit spread while seeking adviceSeparate affected animals when practical and obtain veterinary guidance on contacts, cleaning and normal mixing.
This snapshot is a general guide, not a diagnosis or treatment plan. New, severe or worsening signs require veterinary assessment.
About the condition
Equine salmonellosis is infection with Salmonella enterica bacteria. Clinical expression ranges from an apparently healthy carrier to mild fever and soft manure, severe enterocolitis with shock, or bloodstream infection. The organism is acquired through fecal contamination of feed, water, equipment or the environment. Stress from transport, surgery, hospitalisation, concurrent gastrointestinal disease and broad-spectrum antimicrobial treatment can increase shedding or allow disease to emerge.
Severe intestinal salmonellosis often begins with fever, depression, loss of appetite and neutropenia. Watery, foul diarrhoea may follow within hours. Rapid dehydration, electrolyte loss, acidosis, abdominal pain and endotoxaemia can progress to hypovolaemic shock. Damage to the intestinal barrier permits bacteria and inflammatory products to enter the circulation, creating risks of sepsis, coagulation failure, kidney injury and laminitis. Foals can develop bacteraemia with infection localising in joints or growth plates, sometimes presenting as lameness rather than diarrhoea.
Salmonella is shed in manure and can spread between horses, contaminate facilities and infect people. Shedding may be intermittent, and recovered horses can continue excreting organisms for days to months. A positive result in a horse without signs requires interpretation, but it has important biosecurity implications.
Not every acute diarrhoea is salmonellosis, and clinical appearance cannot identify the organism reliably. Resistance patterns vary, including multidrug-resistant hospital-associated strains. Accurate diagnosis supports both patient care and outbreak investigation. Outcome depends on disease form: carriers may remain well, mild cases can recover with supportive care, and horses with profound neutropenia, septic shock, severe protein loss or laminitis have a guarded prognosis.
Some infected horses shed organisms without diarrhoea, and shedding can be intermittent. A single negative faecal culture therefore cannot reliably clear a suspect horse. Salmonella also poses a direct zoonotic hazard: people can acquire infection from manure, contaminated boots, hands and equipment, with children, older adults and immunocompromised people at greatest risk of severe disease.
Screening & Early Detection
Suspected cases should be isolated immediately while history and samples are collected. Staff should use dedicated footwear, clothing, tools and hand hygiene because the organism is zoonotic. The history should cover recent travel, surgery, antimicrobial exposure, hospital contact, feed and water sources and illness in other animals. Temperatures and manure consistency of exposed horses may be monitored under veterinary biosecurity direction.
Diagnosis combines compatible signs and laboratory detection. Fresh feces submitted in the quantity and transport conditions requested by the laboratory are preferable to a superficial swab. Because shedding is intermittent, three to five consecutive daily cultures or PCR tests may be required. PCR can be sensitive but does not provide an isolate for serotyping or antimicrobial susceptibility, so culture remains important. Blood culture is indicated when bacteraemia is suspected, particularly in foals.
Serial blood counts commonly identify neutropenia, while electrolytes, protein, kidney values, lactate and inflammatory markers assess severity. Environmental sampling can assist outbreak tracing and confirm cleaning effectiveness. A single negative fecal test does not exclude infection, and release from isolation should follow the facility’s veterinarian-directed criteria rather than disappearance of diarrhoea alone.
Treatment & Management
Severe salmonellosis requires intensive supportive care. Intravenous fluids replace water and electrolyte losses, restore circulation and support kidney function. Plasma may be considered for marked protein loss or additional support, while analgesic and anti-endotoxin treatment is selected according to hydration and organ function. Nutritional support, skin care and repeated monitoring are important during prolonged diarrhoea.
Antimicrobial decisions are individual. Adult intestinal salmonellosis without bacteraemia may not improve with routine antibiotics, which can further disturb intestinal flora and select resistance. Systemic antimicrobials are indicated for septicaemia, bacteraemic foals, profound neutropenia with clinical deterioration or another clear veterinary reason, ideally guided by culture and susceptibility. Laminitis surveillance and preventive hoof support are essential throughout the high-risk period.
Isolation continues after clinical improvement because shedding can persist. Manure is removed safely, organic material is cleaned before an appropriate disinfectant is used, and feed and water are protected from fecal contamination. Personnel should understand the human-health risk, especially for children, older people and anyone immunocompromised. Repeated testing may be used to assess shedding according to local policy. Prognosis is reasonable for mild disease but guarded with septic shock, severe hypoproteinaemia, coagulation abnormalities, renal injury or laminitis.
Breeds or species affected
Akhal-Teke
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Anglo-Arabian
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Arabian
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Barb
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Caspian
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Kathiawari
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Marwari
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Shagya Arabian
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Thoroughbred
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American Quarter Horse
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American Paint Horse
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Appaloosa
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Australian Stock Horse
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Brumby
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Waler
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Morgan
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Standardbred
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American Saddlebred
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Tennessee Walking Horse
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Missouri Fox Trotter
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Rocky Mountain Horse
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Peruvian Paso
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Criollo
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Mustang
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Canadian Horse
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Andalusian
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Lusitano
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Lipizzaner
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Friesian
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Dutch Warmblood
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Hanoverian
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Holsteiner
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Oldenburg
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Westphalian
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Trakehner
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Selle Français
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Belgian Warmblood
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Danish Warmblood
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Swedish Warmblood
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Swiss Warmblood
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Australian Warmblood
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Irish Sport Horse
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Cleveland Bay
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Württemberger
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Zangersheide
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Knabstrupper
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Orlov Trotter
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Camargue
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Icelandic Horse
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Pony of the Americas
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Quarter Pony
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Miniature Horse
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Clydesdale
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Shire
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Percheron
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Belgian Draft
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Suffolk Punch
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American Cream Draft
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Ardennes
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Breton
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Boulonnais
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Comtois
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Dutch Draft
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North Swedish Horse
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Norwegian Fjord
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Haflinger
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Gypsy Cob
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Irish Draught
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Welsh Pony and Cob
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Connemara Pony
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New Forest Pony
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Dartmoor Pony
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Exmoor Pony
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Shetland Pony
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Highland Pony
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Fell Pony
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Dales Pony
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Australian Pony
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Finnhorse
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Black Forest Horse
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