Laminitis in Holstein dairy cows is associated with intestinal and mammary dysfunction, systemic inflammation, and microbiota dysregulation.

Laminitis is a major health and production disorder in dairy cows, yet its systemic associations with host physiology and microbiota remain incompletely understood. This exploratory study investigated the relationships among lameness severity, production performance, serum biomarkers, and milk and fecal microbiota. Cows were classified into healthy and laminitic groups using locomotion scoring. While milk composition remained largely stable, laminitic cows exhibited significantly reduced milk yield. Serum analyses revealed elevated inflammatory cytokines, oxidative stress markers, stress hormones, and intestinal barrier indicators, including lipopolysaccharide, diamine oxidase, and D-lactate. Fecal microbiota structure differed significantly between groups, whereas milk microbiota showed limited overall variation. Correlation and network analyses demonstrated preliminary coordinated associations among lameness, reduced production, systemic inflammation, and barrier dysfunction. Furthermore, PICRUSt-based predictions suggested an enriched genetic potential for central carbon metabolism and transcription-related pathways in laminitic cows, while healthy cows showed higher predicted capacities for nutrient processing. Collectively, these exploratory findings provide preliminary evidence that laminitis is associated with systemic physiological disruption and altered predicted microbial capacities. We propose a potential microbiota-associated gut-systemic inflammatory link, accompanied by secondary impairments in mammary physiological function, warranting future validation in larger-scale longitudinal cohorts.