Pathophysiology of abortion in cattle

Abstract

Pathological lesions and inflammatory cell infiltrations in the placenta associated with abortion in cattle do not appear to be so severe or diffuse as to suggest that inflammatory or immunological responses are responsible for the expulsion of the fetus. A failure of trophoblast to secrete progesterone and other steroid hormones, as a result of degeneration or necrosis related to infection increases the excitability of the myometrium. Uterine contractions expel the fetus in the absence of the hormonal cascade which normally controls the fetal ejection reflex.