Equine Fecal Microbiota Changes Associated With Anthelmintic Administration.
Authors: Kunz Isabelle G Z, Reed Kailee J, Metcalf Jessica L, Hassel Diana M, Coleman Robert J, Hess Tanja M, Coleman Stephen J
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Anthelmintic Effects on Equine Gut Microbiota Whilst anthelmintic drugs remain essential for parasite control in horses, their broader effects on gastrointestinal microbial communities remain poorly characterised. Kunz and colleagues administered a single dose of moxidectin and praziquantel (Quest Plus) to ten clinically healthy horses, collecting faecal samples before and after treatment for 16S rRNA gene sequencing analysis. Treatment produced measurable but modest microbiota shifts: alpha diversity (microbial richness and evenness) decreased significantly, and 21 specific bacterial taxa showed significant abundance changes, yet beta diversity (between-individual variation) remained unaffected—suggesting that host factors rather than the drug itself may largely determine individual microbiota responses. The lack of broad-scale dysbiosis following anthelmintic administration is reassuring for routine parasite management, though the pattern of individualised microbial responses warrants further investigation. Understanding which host characteristics (age, diet, prior exposure, baseline microbiota composition) predict susceptibility to microbiota disruption could refine our approach to anthelmintic timing, frequency, and selection in vulnerable populations, particularly young stock or those with compromised gut health.
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Practical Takeaways
- •Anthelmintic treatment produces measurable but limited microbiota changes in healthy horses without clinical signs of helminth infection
- •Individual horses may respond differently to anthelmintics based on host-specific factors; monitor for individual variation rather than assuming uniform microbiota effects
- •The modest nature of these changes suggests anthelmintic use remains justified for parasite control in healthy horses, but awareness of individual response variation is warranted
Key Findings
- •Anthelmintic treatment (Moxidectin and Praziquantel) caused a small but significant decrease in alpha diversity (P < 0.05) in equine fecal microbiota
- •21 taxonomic features were significantly altered after anthelmintic treatment (Padj < 0.05)
- •Beta diversity differences were not significant, suggesting individual host factors may drive variable microbiota responses to anthelmintic treatment
- •Overall microbiota composition was not broadly disrupted despite measurable changes in specific bacterial taxa