Gut Microbiome and Osteoarthritis: Insights From the Naturally Occurring Canine Model of Osteoarthritis

Objective The purpose of this study was to enhance the current knowledge of the relationship between the gut microbiome and osteoarthritis (OA) and associated pain using pet dogs as a clinically relevant translational model. Methods Fecal samples were collected from 93 owned pet dogs. Dogs were designated as either clinically healthy or OA pain using validated methods. Metagenomic profiling was performed through shotgun sequencing using the Illumina NovaSeq platform. MetaPhlAn2 and HUMAnN2 were used to evaluate bacterial taxonomic and pathway relative abundance. Comparisons between healthy and OA‐pain groups were performed individually for each taxa using nonparametric tests following Benjamini and Hochberg adjustment for multiple comparisons. Permutation analysis of variance was performed using Bray‐Curtis distance matrices. All downstream analyses were completed in R. Results No significant differences between healthy and OA‐pain dogs were observed for alpha and beta diversity. We found 13 taxa with nominally significant (P < 0.05) associations with OA case status, but none of the associations remained significant after adjustment for multiple comparisons. No differences in alpha or beta diversities or the Firmicutes to Bacteroidetes ratio were found regarding pain severity, mobility or activity level, age, or body composition score. Conclusion Similar to recent studies in humans, the present study did not demonstrate a significant difference in the fecal microbial communities between dogs with OA pain and healthy control dogs. Future research in this naturally occurring model should expand on these data and relate the gut microbiome to gut permeability and circulating proinflammatory and anti‐inflammatory molecules to better understand the influence of the gut microbiome on OA and OA pain.