Postpartum uterine health in cattle.

Uterine health is often compromised in cattle because postpartum contamination of the uterine lumen by bacteria is ubiquitous, and pathogenic bacteria frequently persist causing clinical disease. The subfertility associated with uterine infection involves perturbation of the hypothalamus, pituitary and ovary, in addition to the direct effects on the uterus, and appears to persist even after clinical resolution of the disease. Absorption of bacterial components from the uterus can prevent the follicular phase LH surge and ovulation. In addition, the first postpartum dominant follicle has a slower growth rate and secretes less estradiol at the end of the growth phase. There are also localised ovarian effects of high uterine bacterial growth density, because fewer first dominant follicles are selected in the ovary ipsilateral than contralateral to the previously gravid uterine horn. Thus, it is important to diagnose and treat uterine disease promptly and effectively. Examination of the contents of the vagina for the presence of pus is the most useful method for diagnosis of endometritis. The character and odor of the vaginal mucus can be scored and this endometritis score is correlated with the growth density of pathogenic bacteria in the uterus, and is prognostic for the likely success of treatment. The challenge for the future is to design prevention and control programs to reduce the incidence of disease, and understand how the immune and endocrine systems are integrated.