[Diagnosis, therapy and endocrinologic parameters of persistent follicles in mares in comparison with preovulatory follicles].

The researchers studied persistent ovarian follicles in mares, comparing their hormone levels and response to therapy with those in preovulatory follicles. They found that hormone levels varied widely in persistent follicles and that directly puncturing these follicles could help return the mares to a normal reproductive cycle.

Research Overview

• This study was conducted during the 1997 breeding season and primarily centered on 17 mares that had been diagnosed with persistent follicles. A further ten mares, with preovulatory follicles, were used as a control group.
• Persistent follicles in 16 of the affected mares were punctured transabdominally, and the researchers measured the concentrations of three hormones – oestradiol, progesterone, and testosterone – in both the follicular fluid and the mares’ blood serum.

Findings

• The research team found a very high variability in the hormone concentrations in the persistent follicles. Based on the ratio of the hormones within individual follicles, they classified eight follicles as ‘intact’, three as ‘undergoing atresia’ (a process of degeneration) and five as ‘luteinized’ (referring to the functional transformation of the follicle post-ovulation).
• All follicles in the control group were rated as being intact due to high oestradiol levels in their follicular fluid.
• No strong correlation was found between the hormone concentrations in the blood serum and that in the follicular fluid. This fact suggests that the hormones do not passively diffuse through the follicular wall.

Implications and Therapeutic Applications

• One significant outcome of the study was that puncturing the persistent follicles helped to return the mares to a physiological estrus cycle (the productive period in mares) within a normal dioestrus period (the non-productive period). Consequently, the researchers suggest that transabdominal puncturing of persistent follicles might be a viable therapeutic technique for affected mares.