Changes in the equine fecal microbiota associated with the use of systemic antimicrobial drugs.

Summary

# Editorial Summary: Antimicrobial Drugs and Equine Fecal Microbiota Systemic antimicrobial administration represents a necessary but potentially disruptive intervention in equine practice, with the intestinal microbiota playing an established role in maintaining gastrointestinal health and function. Costa and colleagues examined faecal bacterial populations in healthy horses before, during, and after treatment with commonly prescribed systemic antimicrobials, using molecular characterisation techniques to track microbiotal composition changes. The research documented significant alterations in bacterial diversity and abundance across different drug classes, with recovery patterns varying substantially depending on the antimicrobial agent used—findings that underscore why post-treatment diarrhoea remains a considerable clinical risk. These results have direct relevance for practitioners selecting antimicrobials and managing post-treatment complications, particularly regarding timing of probiotic or prebiotic interventions and monitoring protocols during recovery. Understanding drug-specific microbiotal impacts enables more informed clinical decision-making, especially in cases where multiple antimicrobial options exist or where individual horses carry heightened dysbiosis risk.

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Key Findings

• •Systemic antimicrobial drugs cause significant disruption to the normal equine fecal microbiota composition
• •Antimicrobial therapy is identified as an important cause of diarrhea in horses through microbiota alteration
• •Changes in bacterial populations occur in healthy horses receiving frequently used antimicrobial drugs

Conditions Studied