The effect of prostaglandin administration to Holstein-Friesian cows at Day 26 postpartum on clinical findings, and histological and bacteriological results of endometrial biopsies at Day 40.

Ninety-two cows that calved between April and August 1984 in a commercial dairy herd were studied. The cows were randomly assigned to receive either cloprostenol (500 mug) or saline placebo on Day 26 postpartum. In addition, each cow was examined per rectum, had three endometrial biopsies taken and milk progesterone level determined. Double-blind techniques were used in administering treatments and in assessing response to treatment. The results of histological and bacteriological assessment of endometrial biopsies and clinical findings at Day 40 were compared between the cows that received prostaglandin at Day 26 and those that did not. Each Day 40 variable which was significantly associated with prostaglandin treatment at Day 26 was regressed against the treatment variable and progesterone level at Day 26 as well as a prostaglandin progesterone interaction term. Prostaglandin-treated cows had less vaginal discharge, smaller diameter uterine horns, less inflammation and fibrosis in the endometrium, and were less likely to have Actinomyces pyogenes isolated from a biopsy at Day 40 than untreated cows. These effects were independent of progesterone level at the time of treatment.