Mid‐gestation pregnancy is not disrupted by a 5‐day gastrointestinal mucosal cytoprotectant oral regimen of misoprostol

Reasons for performing study: To investigate effects of a 5‐day oral misoprostol regimen recommended for use in horses as a gastrointestinal mucosal cytoprotectant during colic on mid‐gestation pregnancies. Objectives: To monitor cervical tone, ultrasonographic characteristics of the uterus, cervix and conceptus, as well as serum progesterone and oestrone sulphate concentrations, and observations of general health, behaviour and comfort of mid‐gestation mares given a 5‐day course of misoprostol or control treatment. Methods: Eleven light horse and pony mares with known breeding dates were administered 5 µg/kg bwt misoprostol orally, twice daily for 5 days. General health and pregnancy status were monitored daily during treatment via general physical examination, as well as palpation and ultrasonography per rectum of the uterus, cervix and conceptus. Jugular serum was obtained during and for 5 days following treatment for assay of progesterone and oestrone sulphate concentrations. Additionally, daily 12 h video samples of the mares were obtained to evaluate behaviour and comfort. Results: All findings, including cervical tone, ultrasonographic characteristics of the uterus, cervix and conceptus, as well as progesterone and oestrone sulphate concentrations, and observations of general health, behaviour and comfort, were similar during misoprostol and control treatment. Conclusions: Treatment of pregnant mares with a gastrointestinal mucosal cytoprotectant regimen of oral misoprostol for 5 days did not disrupt pregnancy, nor adversely affect the general health and comfort of these mares. Additional investigation of treatment at earlier and later stages of gestation, for longer‐term treatment, as well as evaluating neonates for developmental disturbances, would add further information on safety of misoprostol during gestation. Potential relevance: These results provide some assurance of safety of a 5‐day gastrointestinal mucosal cytopretectant regimen of oral misprostol in mid‐gestation pregnant mares.