Comparison of the fecal microbiota of healthy horses and horses with colitis by high throughput sequencing of the V3-V5 region of the 16S rRNA gene.
Authors: Costa Marcio C, Arroyo Luis G, Allen-Vercoe Emma, Stämpfli Henry R, Kim Peter T, Sturgeon Amy, Weese J Scott
Journal: PloS one
Summary
# Editorial Summary The equine hindgut microbiota represents an extraordinarily complex ecosystem, yet until relatively recently, veterinary understanding of its composition relied on culture-based methods that captured only a fraction of the bacterial community. Costa and colleagues employed high-throughput 16S rRNA gene sequencing to characterise faecal microbiota from healthy horses and those with undifferentiated colitis, analysing nearly 200,000 bacterial sequences across both groups. Healthy horses displayed a microbiota dominated by Firmicutes (68%), particularly members of the Clostridia class and Lachnospiraceae family, with lower proportions of Bacteroidetes (14%) and Proteobacteria (10%); colitic horses showed a markedly dysbiotic profile with Bacteroidetes surging to 40%, Firmicutes declining to 30%, increased Proteobacteria (18%), and notably elevated Fusobacteria not seen in healthy animals. This fundamental shift in microbial architecture suggests colitis may result from broad dysbiosis rather than simple pathogenic overgrowth, implying that therapeutic strategies targeting microbial diversity restoration—through dietary modification, selective antimicrobials, or probiotic/prebiotic interventions—warrant investigation alongside traditional supportive care. For practitioners, these findings provide baseline microbiological signatures against which to evaluate emerging diagnostic tools and underpin rational development of evidence-based dysbiosis management protocols in colitic horses.
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Practical Takeaways
- •Colitis in horses involves complex microbiota imbalance rather than infection by one organism, suggesting treatment should target restoring healthy microbial balance rather than targeting single pathogens
- •Clostridia and Lachnospiraceae bacteria are markers of healthy equine gut function; probiotics or feeding strategies that support these groups may be protective
- •Microbiome profiling could potentially help differentiate colitis cases and guide more targeted therapeutic interventions in clinical practice
Key Findings
- •Healthy horses have 68% Firmicutes dominance vs 30% in colitis cases, with Bacteroidetes reversed (14% vs 40%)
- •Clostridia class bacteria significantly more abundant in healthy horses; Lachnospiraceae family most frequently shared among healthy individuals
- •Colitis horses have significantly elevated Fusobacteria; healthy horses have higher Actinobacteria and Spirochaetes
- •Colitis appears to be a disease of gut dysbiosis rather than single pathogen overgrowth