Uterine defence mechanisms in the mare

Breeding or insemination of mares is followed by a transient infection and inflammation. Normal mares eliminate bacteria and clear inflammatory by-products rapidly. Some mares are not capable of doing this. Studies on immunoglobulins, opsonins, chemotaxis and migration and phagocytosis of neutrophils have failed to show good grounds for susceptibility to uterine infections. The latest studies indicate that differences between these two kinds of mares are best explained by factors involved in uterine clearance: cervical dilation, myometrial activity and lymphatic drainage.