Gastric microbiome in horses with and without equine glandular gastric disease

Abstract Background The role of the gastric microbiome in development or persistence of equine glandular gastric disease (EGGD) remains to be investigated. Hypothesis/Objectives The objective was to characterize the glandular mucosal and gastric fluid microbiomes of horses with and without EGGD. It was hypothesized that differences in the mucosal microbiome are associated with EGGD. Animals Twenty‐four horses were enrolled. Methods Gastroscopy was performed and EGGD scores recorded (score 0, n = 6; score 1, n = 8; score ≥2, n = 10). Gastric fluid and pinch biopsies of healthy glandular mucosa and EGGD lesions were collected via gastroscope. 16S rRNA amplicon sequencing of the gastric fluid and glandular mucosal biopsies was performed. Relationships between gastric fluid and mucosal microbial community composition were evaluated among EGGD score groups (EGGD 0‐BX, EGGD 1‐BX, EGGD ≥2‐BX) and among endoscopic appearances: controls from horses without EGGD and normal areas, hyperemic areas, and lesions from horses with EGGD. Results Microbial community structure of mucosal biopsies differed among EGGD score groups (Jaccard similarity index; P = .009). Principal coordinate analysis showed separate clusters for EGGD 0‐BX and EGGD ≥2‐BX. Conclusions and Clinical Importance A modest difference was detected in the community structure of the gastric glandular mucosal microbiome in association with EGGD score.