Factors associated with equine shedding of multi-drug-resistant Salmonella enterica and its impact on health outcomes.
Authors: Burgess B A, Bauknecht K, Slovis N M, Morley P S
Journal: Equine veterinary journal
Summary
# Factors associated with equine shedding of multi-drug-resistant Salmonella enterica and its impact on health outcomes Multi-drug-resistant Salmonella enterica represents a significant nosocomial threat in equine veterinary practice, driving high mortality rates and considerable economic losses during hospital outbreaks. Burgess and colleagues undertook a retrospective case-control analysis of 373 hospitalised horses (94 culture-positive, 279 culture-negative) to identify factors predisposing to MDR-Salmonella shedding, followed by prospective long-term outcome assessment via telephone interviews with owners of discharged animals and their stablemates. The key finding was counterintuitive: whilst diarrhoea during hospitalisation significantly increased shedding likelihood (odds ratio 1.88), the isolates recovered were predominantly antimicrobial-susceptible strains rather than MDR phenotypes. Critically, neither shedding status nor MDR strain recovery predicted worse survival, increased colic incidence, faecal abnormalities, or disease transmission to stablemates post-discharge—suggesting that owner-implemented biosecurity measures may have mitigated transmission risk. Despite these reassuring outcomes, the authors emphasise that evidence-based protocols should remain non-negotiable: recently hospitalised horses warrant isolation periods with rigorous hygiene practices regardless of shedding status, particularly given the study's limitations (reliance on medical record quality and owner recall, regional population specificity to central Kentucky).
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Practical Takeaways
- •Recently hospitalized horses should be segregated after discharge and managed with rigorous hygiene practices, regardless of Salmonella status, to prevent transmission to stablemates
- •The presence of diarrhea during hospitalization is a risk factor for Salmonella shedding; implement appropriate biosecurity measures for these horses
- •Owner-implemented biosecurity precautions appear effective at preventing adverse health outcomes from Salmonella shedding in the post-discharge period
Key Findings
- •Horses with diarrhea during hospitalization were 1.88 times more likely to shed Salmonella compared to those without diarrhea (95% CI 1.02-3.45), though isolates tended to be susceptible strains
- •Antimicrobial therapy during hospitalization was not associated with shedding or recovery of MDR strains
- •Salmonella shedding did not increase long-term risk for non-survival, colic, abnormal feces, or hospitalization in previously hospitalized horses or their stablemates