Differences in the equine faecal microbiota between horses presenting to a tertiary referral hospital for colic compared with an elective surgical procedure.
Authors: Stewart H L, Southwood L L, Indugu N, Vecchiarelli B, Engiles J B, Pitta D
Journal: Equine veterinary journal
Summary
# Editorial Summary Disruption of the faecal microbiota has emerged as a potentially significant feature in equine colic, yet comparative data from clinical populations remain limited. This prospective study analysed faecal samples from 30 horses presenting for emergency colic treatment and 10 control horses admitted for elective surgery, using 16S rRNA gene sequencing and advanced statistical analysis to characterise bacterial community composition, diversity and relative abundance between groups. Horses with colic demonstrated substantially reduced bacterial species richness and Shannon diversity indices (both P<0.001), alongside significant compositional differences in their microbial communities (PERMANOVA, P=0.001); notably, beneficial commensals including *Prevotella*, *Clostridia* and *Lachnospiraceae* were depleted, whilst potentially pathogenic taxa such as *Streptococcus* and *Sphaerochaeta* were enriched in colic cases compared with healthy controls. These findings align with dysbiosis patterns documented in other species with gastrointestinal disease and suggest that microbiota analysis may contribute to understanding colic aetiology, though the study's modest sample size limits generalisation. Farriers and equine practitioners should recognise that acute colic involves measurable shifts in the hindgut bacterial ecosystem; future investigations stratifying by colic type and tracking microbiota recovery during convalescence would clarify whether dysbiosis is a cause, consequence or comorbidity, and potentially inform probiotic or dietary interventions.
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Practical Takeaways
- •Colic in horses is associated with dysbiosis (reduced bacterial diversity and altered microbial composition), suggesting microbiota analysis may help understand colic pathophysiology
- •Loss of beneficial commensal bacteria and overgrowth of potentially pathogenic organisms in colic cases suggests microbiota modulation (probiotics, prebiotics) could be investigated as therapeutic targets
- •Faecal microbiota profiling could potentially become a diagnostic or prognostic tool for colic, though larger studies across different colic types are needed before clinical application
Key Findings
- •Horses with colic had significantly fewer bacterial species (P<0.001) and lower diversity (P<0.001) compared to elective surgery controls
- •Bacterial community composition differed significantly between colic and elective groups (PERMANOVA P=0.001)
- •Commensal bacteria including Prevotella, Clostridia, and Lachnospiraceae were reduced in colic cases, while Christenellaceae, Streptococcus, and Sphaerochaeta were increased
- •14 bacterial lineages at the genus level showed significant differences between colic and elective cases