The ovarian cycle of the mare can become misaligned for various reasons, two of which are most frequently encountered: persistent corpus luteum (which takes the place of the egg) and the unusually long duration of heat that are anovulatory. These disturbances will affect fertility.
Administered Or-Ovary during the period of heat. If necessary add a de-stressing as Or-Calm or Or-Stress. Massaging lumbar acupuncture points with oil Or-Relax.