Cervical relaxation and increased secretion of mucus in the cervix, anterior vagina and uterus are observed in the proestrual reproductive tract. In contrast, estradiol from the maturing follicles produces dramatic changes in the reproductive tract during estrus. Most of the multiple large cysts have some luteinized tissue and produce sufficient progesterone to inhibit estrous cyclicity. Sows with these cysts usually fail to exhibit estrus and are culled from the herd. Since these animals fail to ovulate, it is unlikely that these animals conceive.
Anestrous sows are animals that fail to return to estrus following weaning.
Uterine Abnormalities Metritis and endometritis often are noted as abnormalities of the uterus. Metritis is inflammation of multiple layers of the uterine wall, while endometritis refers to inflammation of the uterine lining or endometrium. The contents of affected uteri vary widely, reflecting the pathogenic organism, chronicity of infection and the stage of the estrous cycle. Uteri may be distended with debris and exhibit thickening of the wall. Our clinical research revealed that the uteri of affected sows may be devoid of debris after a standing estrus.