In all species, acute puerperal metritis occurs within the first 10–14 days postpartum. It results from contamination of the reproductive tract at parturition and often, but not invariably, follows complicated parturition. Important causative organisms in cattle include Escherichia coli and Trueperella (Arcanobacterium) pyogenes, but culture-independent studies have demonstrated the dominant role of gram-negative anaerobic bacteria such as Prevotella melaninogenica and Fusobacterium necrophorum. The condition is usually acute in onset. Affected cows, mares, ewes, does, or sows are depressed, febrile, and inappetent. A fetid, watery uterine discharge is characteristic of the condition in cows but may not be conspicuous in other species. Milk production is diminished, and nursing young may show signs of food deprivation.
Acute puerperal metritis responds well to systemic antimicrobial therapy combined, if necessary, with NSAIDs and other supportive measures such as fluid therapy. Cephalosporin antibiotics or penicillin are considered most appropriate for systemic treatment of cows with metritis because they are active against most common pathogens, reach therapeutic levels in endometrial tissues, and may help prevent some of the potential sequelae of metritis and endometritis, such as endocarditis or renal disease. Oxytetracycline requires administration at high levels (11 mg/kg, bid) to maintain uterine tissue concentrations of 5 mcg/g, which is below the minimal inhibitory concentration (MIC) for many strains of pathogenic T pyogenes. Drainage of the uterine content may be advantageous but should be attempted only after initiation of antimicrobial therapy; it should be done very carefully because the inflamed uterus may be friable, and manipulation of the uterus may result in bacteremia.