Risk factors associated with an outbreak of equine coronavirus at a large farm in North Carolina.
Authors: Hepworth-Warren Kate L, Erwin Sara J, Moore Caroline B, Talbot James R, Young Kimberly A S, Neault Michael J, Haugland Jennifer C, Robertson James B, Blikslager Anthony T
Journal: Frontiers in veterinary science
Summary
# Equine Coronavirus: Management Factors Drive Infection Risk Equine coronavirus outbreaks present variable clinical presentations and mortality, yet evidence regarding infection risk factors remains limited in the peer-reviewed literature. Kate Hepworth-Warren and colleagues conducted a retrospective cohort study of 135 horses on a North Carolina farm during an ECoV outbreak, collecting data on age, breed, housing, activity level, and feeding protocols, then analysing these factors using logistic regression and Fisher's exact testing. PCR testing identified 43 of 54 horses (79.6%) as positive for ECoV, though only 17 animals (12.6%) developed clinical signs—notably, 35.3% of those affected presented with colic, including three cases of small colon impaction requiring surgical intervention in two instances. Stalled housing emerged as the strongest risk factor (odds ratio 167.1), alongside proximity to positive horses (OR 7.5), active work participation (OR 26.9), and rationed hay feeding versus ad libitum access (OR 1,558), with alfalfa hay specifically conferring substantial infection risk (OR 1,558). These findings underscore that intensive management practices—particularly common in sport horse operations—substantially amplify ECoV transmission risk; practitioners should counsel clients on the importance of housing flexibility, unrestricted forage access where feasible, and activity modification during outbreaks, whilst remaining alert to colic as a significant clinical manifestation beyond respiratory or gastrointestinal signs alone.
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Practical Takeaways
- •Be alert to variable clinical presentations of ECoV including severe colic and impaction; not all infected horses show obvious signs
- •Intensive management practices common in show operations (stalling, rationed hay, active work) significantly increase ECoV infection risk—consider management modifications during outbreaks
- •Horses with known ECoV exposure should be monitored closely for colic; small colon impaction may require surgery and should be on the differential diagnosis
Key Findings
- •79.6% of tested horses (43/54) were PCR-positive for ECoV, but only 12.6% developed clinical signs
- •Stalling as primary housing carried highest risk for infection (OR 167.1), followed by rationed hay feeding (OR 1,558)
- •35.3% of clinically affected horses (6/17) exhibited colic signs, with 2 horses requiring surgical intervention for small colon impaction
- •Housing proximity to positive horses and active work status were significant risk factors (OR 7.5 and OR 26.9 respectively)