Metritis is inflammation of the uterus, typically involving both the endometrium and the deeper myometrial layers. In horses, the condition most commonly occurs in the days immediately following foaling when bacteria gain access to the uterus through a traumatized or incompletely closed cervix. Common causative organisms include Escherichia coli, Streptococcus equi subsp. zooepidemicus, and Klebsiella pneumoniae. Affected mares typically present with fever, depression, and a malodorous vaginal discharge; in severe cases the condition can progress to septicemia or laminitis. Diagnosis is confirmed by uterine culture and cytology. Treatment involves uterine lavage to remove contaminated material, systemic antibiotics, and hormonal support to restore normal uterine tone. Early recognition and treatment are essential to preserve future reproductive function. See also onset in the days following foaling and dam for related reproductive context, and the mare as the primary patient for the primary subject.