Effect of oral administration of omeprazole on the microbiota of the gastric glandular mucosa and feces of healthy horses.
Authors: Cerri Simona, Taminiau Bernard, de Lusancay Alexandra Hache-Carré, Lecoq Laureline, Amory Hélène, Daube Georges, Cesarini Carla
Journal: Journal of veterinary internal medicine
Summary
# Omeprazole's Limited Impact on Equine Gastrointestinal Microbiota Proton pump inhibitors like omeprazole are commonly prescribed in equine practice for gastric ulcer management, yet their effects on the microbial ecosystem remain poorly understood in horses despite well-documented microbiota disruption in humans and dogs. Cerri and colleagues conducted a controlled prospective study on eight healthy, straw-bedded horses fed exclusively haylage, collecting transendoscopic gastric glandular biopsies, gastric fluid, and faecal samples before and after seven days of omeprazole administration (4 mg/kg once daily), with bacterial profiling performed via 16S rRNA amplicon sequencing. Whilst omeprazole successfully raised gastric pH (P = 0.006), the drug produced surprisingly modest microbiological changes: fecal microbiota remained stable, and glandular gastric microbiota showed no significant compositional shifts, though certain genera became more dominant and *Clostridium sensu stricto_1* demonstrated a statistically significant increase (P = 0.002). These findings suggest that horses may be considerably more resilient to omeprazole-induced dysbiosis than other species, though the clinical significance of increased *Clostridium* warrants further investigation in larger populations and in animals with pre-existing gastric disease. For practitioners, this research provides reassurance that short-term omeprazole use in healthy horses appears unlikely to trigger the profound microbiota disruption seen in humans and dogs, though extended treatment protocols and immunocompromised animals merit continued caution.
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Practical Takeaways
- •Omeprazole may have fewer deleterious effects on equine gastrointestinal microbiota compared to effects documented in humans and dogs, potentially making it safer for routine use
- •While overall microbiota composition remains relatively stable, monitor for Clostridium proliferation in horses receiving prolonged omeprazole therapy
- •Short-term omeprazole use (7 days) in healthy horses does not appear to cause the microbiota disruptions associated with Clostridioides difficile enterocolitis risk seen in other species
Key Findings
- •Gastric pH increased significantly after 7 days of omeprazole administration at 4 mg/kg PO q24h (P = 0.006)
- •Omeprazole did not induce significant major changes in fecal or gastric glandular microbiota composition overall
- •Clostridium sensu stricto_1 showed significant increase in gastric glandular mucosa after omeprazole (P = 0.002)
- •Certain microbial genera became more predominant in gastric mucosa with lower Simpson's evenness (P = 0.05), suggesting fewer dominant species