Differential effects of selective and non-selective cyclooxygenase inhibitors on fecal microbiota in adult horses.
Authors: Whitfield-Cargile Canaan M, Chamoun-Emanuelli Ana M, Cohen Noah D, Richardson Lauren M, Ajami Nadim J, Dockery Hannah J
Journal: PloS one
Summary
# Editorial Summary: NSAIDs and Equine Gut Microbiota Both non-selective and COX-2-selective NSAIDs trigger temporary dysbiosis in horses, according to a 2018 investigation comparing phenylbutazone and firocoxib administration over a 10-day treatment period. Researchers analysed faecal samples from 25 adult horses using 16S rRNA gene sequencing to characterise microbial composition and diversity, collecting samples at baseline, day 5, day 10, and day 25. Whilst the control group's microbiota remained stable throughout, both NSAID-treated groups demonstrated reduced microbial diversity and significant alterations to their microbiota profiles, with the most pronounced changes occurring at day 10 of treatment; the inferred metagenome also showed marked functional changes at this timepoint before beginning to recover. These findings are clinically significant because dysbiosis has been implicated in several prevalent equine conditions—including colic, colitis, infectious enteritis, and laminitis—suggesting that extended or repeated NSAID use warrants careful consideration and potentially concurrent strategies to support gastrointestinal health. The temporary nature of these changes indicates that short-term NSAID therapy may pose limited risk, yet practitioners should remain vigilant for dysbiosis-related complications, particularly in horses requiring prolonged anti-inflammatory treatment or with pre-existing gastrointestinal vulnerability.
Read the full abstract on PubMed
Practical Takeaways
- •Both traditional and selective NSAIDs cause temporary but significant disruption to the hindgut microbiota—minimize treatment duration when possible and monitor for GI signs during and after therapy
- •NSAID dysbiosis resolves within 2 weeks of stopping treatment, but timing matters if the horse is already at risk for colic or colitis
- •Consider probiotic or prebiotic support during NSAID courses, particularly in horses with prior GI disease, to help maintain microbial stability
Key Findings
- •Both phenylbutazone (non-selective COX inhibitor) and firocoxib (COX-2-selective) decreased fecal microbiota diversity in horses over 10 days of treatment
- •Microbiota alterations were most pronounced at day 10 of NSAID administration, with partial recovery by day 25
- •Both drug classes caused similar dysbiotic effects despite different COX selectivity profiles
- •NSAID-induced dysbiosis may contribute to colic, colitis, enteric infections, and laminitis in horses