The effects of ovarian hormones and ACTH on uterine defense to Corynebacterium pyogenes in cows

Ovariectomized cows were treated with either estrogen, progesterone or adrenogorticotropic hormone (ACTH). Each cow's uterus was inoculated with 1x10(6)Corynebacterium pyogenes organisms. The cows were evaluated by rectal examination for signs of uterine infection. Peripheral leukocytic phagocytosis was determined by chemiluminescence at the beginning (Day 4) and end (Day 21) of the experiment. Uterine cultures were obtained at the end. None of the estrogen-treated cows developed signs of uterine infection, but all the other cows did develop uterine disease. All the infected cows showed clinical improvement at the experimental end (Day 21). There were no differences between groups for leukocytic phagocytosis on Day 4, but on Day 21, values for progesterone-treated and control cows were similar but greater than those for estrogen or ACTH-treated cows, which were similar. Leukocytic phagocytosis values for all cows were lower on Day 21 than on Day 4. Most of the estrogen- and ACTH-treated cows had negative intrauterine cultures on Day 21 while most of controls and progesterone-treated cows had positive cultures.