Gut microbiome signatures precede chronic kidney disease diagnosis in a large canine cohort

Chronic kidney disease (CKD)-associated dysbiosis is well described after diagnosis, but whether microbial changes precede clinical recognition is unclear. We integrated insurance claims, fecal and oral 16S rRNA profiles, and clinical laboratory data from companion dogs. Among 140,025 dogs, lower gut microbial diversity was associated with incident CKD after adjustment for age, sex and body size. Prediagnostic samples showed reduced evenness-related diversity, modest community shifts and seven differentially abundant genera. A five-genus score was elevated more than two years before diagnosis, although it was derived and evaluated in the same cohort and was not intended as a predictive model. In a laboratory subset, microbial changes preceded the largest increases in blood urea nitrogen and creatinine. Paired oral-gut samples showed limited exploratory associations between periodontal-associated taxa and the gut score. These findings identify microbial features associated with future claims-defined canine CKD and support independent validation and mechanistic investigation.