Endometritis

Clinical endometritis shows as purulent or mucopurulent vaginal discharge without fever or other systemic illness; one review places it more than 21 days after calving and a later review at 28 days or more. Subclinical endometritis has no discharge and is recognised only by endometrial cytology, with more than 18% neutrophils at 21-33 days or more than 10% at 34-47 days postpartum. Vaginoscopy, fluid in the uterine lumen on ultrasound and an enlarged cervix support the diagnosis, though each has low sensitivity.

Endometritis is inflammation of the endometrium, the uterine lining, without the whole-wall involvement and systemic illness that define metritis. After calving the uterus is contaminated by a wide range of bacteria; Escherichia coli, Trueperella pyogenes, Fusobacterium necrophorum and Prevotella species dominate disease. Toll-like receptor 4 on uterine cells recognises lipopolysaccharide from Gram-negative bacteria, triggering pro-inflammatory cytokines and recruiting neutrophils into the epithelium and stroma. The inflammation reaches beyond the uterus: cytokines disrupt hypothalamic-pituitary-ovarian signalling, suppress luteinising hormone and delay the return of oestrous cycles, so fertility falls even in cows with no visible discharge.

Described chiefly in postpartum dairy cows. One review puts clinical endometritis at about 5-25% of cows and subclinical endometritis at about 30-50%. More than 200 bacterial species have been found in the uterus early after calving. Risk rises after retained placenta, dystocia, twin births, stillbirth and prolonged calving, and with negative energy balance, ketosis, hypocalcaemia and deficiencies of selenium, zinc and vitamin E, which weaken uterine defences. Postpartum uterine disease causes large economic losses through reduced reproductive efficiency and milk yield.

Metritis involves the whole uterine wall, usually within 10 days of calving, with an enlarged flaccid uterus, fetid red-brown discharge and fever, anorexia and a drop in milk yield. Pyometra is pus retained in the uterus with a persistent corpus luteum and no oestrous cycling. Subclinical endometritis lacks discharge and is detected only by cytology.

Uterus (endometrium), cervix, vagina, ovaries, hypothalamic-pituitary axis

Hygiene at calving; limiting dystocia and retained placenta; managing negative energy balance, ketosis and hypocalcaemia; adequate selenium, zinc and vitamin E; antimicrobial stewardship within integrated herd health management.

Cows with endometritis have 17-20% lower conception rates and take about 27% longer to become pregnant. Prostaglandin F2-alpha is advised for cows with a corpus luteum; early detection and treatment allow timely rebreeding.