Risk factors for the development of haemorrhagic anovulatory follicles in the mare.

This study sought to understand the risk factors and development of hemorrhagic anovulatory follicles (HAFs) in horse breeding, a condition which leads infertility, by analyzing detailed reproductive and ultrasound records of seven mares over their reproductive lives.

Study Objective

• The study aimed to explore and detail the ultrasonographic manifestation and occurrence of HAFs in mares and identify risk factors that could influence its occurrence.

Methodology

• Detailed reproductive histories and ultrasound results from seven mares, gathered over their reproductive lifespans of over 10 years and 612 oestrous cycles, were analyzed.
• The study made use of a statistical mixed model.

Major Findings

• The research identified that two out of the seven mares had an abnormally high incidence of HAFs, about 25%.
• The study discovered that the time of season and use of induction treatments, specifically Cloprostenol, could influence the occurrence of HAFs.
• The researchers speculated that the early-enhanced stimulatory effects of LH (Luteinizing Hormone) on an ovary with the presence of small, immature follicles might increase the risk of ovulatory failure, leading to the development of HAFs later in the cycle.

Conclusion and Implications

• From their findings, the researchers concluded that mares are at a greater risk of developing HAFs during the months of peak follicular activity (May to August) and after receiving hormone treatments to induce oestrus and ovulation.
• The study offers practical knowledge for practitioners to better understand horse reproductive health and improve the reproductive management of mares, especially those with an abnormally high incidence of HAFs.
• From a research perspective, the study provides useful insights towards understanding the nature of this phenomenon for more in-depth investigation.