Equine Disorders of the Cervix Study Guide

Overview and Clinical Importance

The equine cervix is a critical sphincter-like structure that serves as the gateway between the vagina and uterus, playing essential roles in fertility, pregnancy maintenance, and protection against uterine contamination. The cervix is approximately 5-8 cm in length and 2-5 cm in diameter, composed of smooth muscle rich in elastic fibers. Disorders of the cervix represent significant causes of subfertility and infertility in mares, making this topic highly relevant for the NAVLE examination.

Understanding cervical pathology is essential because the cervix must perform seemingly contradictory functions: it must remain tightly closed during diestrus and pregnancy to protect the conceptus, yet relax adequately during estrus to allow semen deposition and uterine drainage. Any disruption to this dynamic function results in reproductive failure.

Normal Cervical Anatomy and Physiology

The equine cervix is a thick-walled muscular tube that protrudes 2-4 cm caudally into the vaginal fornix, creating a characteristic appearance often described as a "small volcano." The cervical mucosa is arranged in longitudinal folds that are continuous with the endometrial folds of the uterine body. This simple folding pattern (unlike the transverse rings seen in ruminants) allows for easy digital and instrumental passage during breeding management.