Practical approach to medication selection in the pregnant mare

Abstract

Medications selected to treat problems of pregnancy in the mare must be simultaneously safe for the mare, safe for the developing fetus and able to penetrate the placental barrier. With consideration of these factors, the practitioner must determine when and for how long to administer therapy. Monitoring equine pregnancy can be challenging, owing to the size of the equine abdomen (precluding visualisation of the entire fetoplacental unit), individual variation in the appearance of the reproductive tract, and (typically) minimal clinical signs of pregnancy compromise until late in a disease process. A large proportion of currently available literature regarding medication use in the pregnant mare focuses on those pharmaceuticals which may be of use in treating placentitis, leaving the practitioner to extrapolate from these findings when managing clinical cases that do not fit into a tidy diagnosis; the aim of this paper is to aid the practitioner with making rational choices of medications using evidence-based medicine, while simultaneously considering a One Health perspective. This paper is an extension of an article originally prepared for the 2023 Proceedings of the American Association of Equine Practitioners, produced with permission.