Hormonal therapy is often used in performance mares to prevent estrous behavior. A wide variety of options are currently available, including hormonal, nonhormonal, and immunologic methods to modulate estrous behavior in mares.

Rates of ovarian quiescence in foaling mares or reports of ovarian failure are low. In foaling mares, lactational anestrus may be behavioral, related to fescue endophyte toxicosis or physiologic factors.

A variety of protocols have been reported to induce lactation in mares that are used as surrogate dams or that have poor lactation.

References from the Hormonal Breeding Management of the Mare chapter of Equine Breeding Management and Artificial Insemination.

Prostaglandin and cloprostenol have been used at luteolytic dosages after breeding and before ovulation to induce sustained uterine contractures in subfertile mares that accumulate fluid.

It is an increasing trend in the equine industry to engage in managed natural breeding and assisted reproductive techniques that require the regulation of estrus and ovulation.

Based on many studies with average mares and average stallions, we should expect the fertility (pregnancy rate) on a per cycle basis to be about 50% using natural cover or AI.

Estrus synchronization in horses has been problematic because of the long duration of behavioral estrus and the variable time frame to ovulation during estrus.