Kong et al. [64] provided definitive evidence that dysbiotic gut microbiota actively contribute to lactation mastitis by demonstrating that fecal microbiota transplantation from mastitis patients induced systemic inflammation in recipient mice, characterized by elevated pro-inflammatory cytokines IL-4, IL-17, MPO, IL-6, IL-1β, and TNF-α. The gene discussed is IL17A; the disease is mastitis.