Mare reproductive challenges can range from endometritis to ovarian irregularities such as hemorrhagic anovulatory follicles, ovarian hematomas, and persistent corpora lutea, all of which can disrupt normal cycles and fertility. Older mares often face anatomical complications that increase contamination and impair conception. Hormonal tumors such as granulosa-theca cell tumors might spur erratic behaviors and cycle abnormalities, while pituitary pars intermedia dysfunction (PPID, formerly Cushing’s disease) can further dampen reproductive performance by causing abnormal cycles, anovulation, and recurring endometritis. Vigilant diagnostics—including ultrasound, hormone panels, and uterine evaluation—are essential in identifying and managing these issues efficiently. 

During this Ask TheHorse Live Q&A two experts answer your questions about common mare reproductive problems. 

This episode is sponsored by Equithrive.

About the Experts:

Carleigh Fedorka, PhD, assistant professor of equine reproductive physiology at Colorado State University, in Fort Collins, is a global expert in reproductive immunology. She has focused her research on understanding the relationship between the immune system and the reproductive tract, evaluating the efficacy of treatments on various reproductive disorders, and discovering biomarkers for reproductive health. Fedorka earned her BS degree from St. Lawrence University, in Canton, New York, and her PhD in Veterinary Sciences from the University of Kentucky, in Lexington, after working in the industry as a manager of a commercial Thoroughbred breeding farm. She maintains a presence in the equine industry by retraining countless off the track Thoroughbreds, including her personal event horses Judge Johnny (JJ) and Strike Two (Jeter). In her spare time, she enjoys fly fishing, spending time with her husband and their dog, and cheering on the Buffalo Bills.

Jenna Ward, DVM, Dipl. ACT, is a clinician and lecturer in large animal reproduction at the University of Pennsylvania's New Bolton Center, in Kennett Square. She earned her DVM at Texas A&M University, in College Station. Ward's research includes stallion reproductive health and genetic-related embryonic loss in horses.