Prevalence of and risk factors associated with Salmonella shedding among equids presented to a veterinary teaching hospital for colic (2013-2018).
Authors: Kilcoyne Isabelle, Magdesian K Gary, Guerra Margherita, Dechant Julie E, Spier Sharon J, Kass Philip H
Journal: Equine veterinary journal
Summary
# Salmonella shedding in colic cases: prevalence, risk factors and practical implications Over a five-year period at a veterinary teaching hospital, Kilcoyne and colleagues identified Salmonella shedding in 3.5% (56 of 1,585) of horses presenting with colic, demonstrating a lower prevalence than previously documented in equine literature. Using a case-control methodology comparing positive Salmonella shedders with negative controls, the researchers applied logistic regression to identify clinical and pathological variables associated with infection. Several distinct risk factors emerged at presentation: horses shedding Salmonella were significantly more likely to present during July (7.2 times increased odds), report a fever history (53.5-fold increase in odds), demonstrate elevated blood lactate concentrations (1.6-fold increase per unit), and paradoxically show neutropenia rather than neutrophilia. Amongst hospitalised cases, shedding horses developed fever at 4.8 times higher frequency and gastric reflux at 10 times higher frequency than non-shedding colic controls. These findings offer practical value to practitioners managing acute colic, particularly in seasonal contexts and when specific clinical indicators manifest: the strong association between fever (present or developing) and Salmonella shedding should prompt earlier isolation protocols and barrier nursing measures. The striking relationship between gastric reflux and shedding status warrants further investigation but may reflect intestinal compromise characteristic of salmonellosis. Whilst the retrospective study design and reliance on single faecal samples introduce inherent limitations, identifying these clinical predictors equips clinicians to implement timely biosecurity precautions, preventing nosocomial transmission in busy referral environments.
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Practical Takeaways
- •When evaluating colic cases, particularly during summer months, watch for fever and elevated lactate as red flags for potential Salmonella shedding, allowing earlier implementation of isolation protocols
- •Development of reflux or persistent fever during hospitalization for colic should heighten suspicion for Salmonella shedding and prompt appropriate biosecurity measures to protect other horses and staff
- •Although Salmonella shedding prevalence in colic populations is relatively low (3.5%), identifying high-risk cases through clinical predictors enables targeted and effective barrier nursing without unnecessary blanket precautions
Key Findings
- •Salmonella shedding prevalence was 3.5% (56/1585) in colic cases presenting to a referral clinic
- •Equids shedding Salmonella were 7.2 times more likely to present in July and 53.5 times more likely to have a fever history
- •Increased lactate and neutropenia at presentation were associated with Salmonella shedding (OR=1.6 and OR=0.79 respectively)
- •Hospitalized Salmonella-shedding horses were 10.1 times more likely to develop reflux and 4.8 times more likely to be febrile during hospitalization