Unlike other farm species that have cervical rings, the cervix of the mare has longitudinal folds that are continuous with the endometrial folds in the uterine body. The orientation of the folds are significant in that the longitudinal folds allow easy passage of the inseminator's finger and pipette during artificial insemination.

The cervix is under hormonal control. The cervical epithelial glands produce a thin mucous during estrus to provide lubrication for the insertion of the glans penis of the stallion and a thick mucous to seal the cervix during diestrus and pregnancy. During diestrus, the cervix is tightly contracted and secretes a small amount of thick mucous. During estrus, the cervix becomes relaxed, protrudes into the vagina and produces a watery secretion.

The cervix expands significantly during parturition to allow the foal to pass.