Exploration of Safety of a Gastrointestinal Mucosal Cytoprotectant, Oral Misoprostol Regimen in Early-Gestation Mares

Fourteen of 15 early-gestation pregnancies appeared unaffected by a gastrointestinal mucosal cytoprotectant oral misoprostol regimen (GMCOMR). Eight mares allowed to carry to term delivered normal foals. Authors’ address: School of Veterinary Medicine, University of Pennsylvania, New Bolton Center, 382 West Street Road, Kennett Square, PA 19348; email: [email protected]. edu.

1. Introduction

Misoprostol, a prostaglandin E1 analog, has both gastrointestinal cytoprotectant and abortigenic properties, with increased risk for neurologic, musculoskeletal, and cognitive defects following human fetal exposure. In previous work in mares, 11 midgestation pregnancies appeared unaffected by administration of a gastrointestinal mucosal cytoprotectant oral misoprostol regimen (GMCOMR).¹ Here we explored the safety of the same GMCOMR in early-gestation pregnancies and resulting neonates.

2. Materials and Methods

Eleven healthy pony mares and four healthy horse mares in early gestation (37–85 days) were administered a GMCOMR (3.5–5 mcg/kg, Q12, PO for 5 consecutive days). Serum samples for progesterone assay were obtained daily during treatment and for five days after treatment had ended. Pregnancies were monitored by transrectal palpation and ultrasonography. Four horse and two pony pregnancies were purposely terminated two (n = 1) to five (n = 5) weeks after treatment had ended. Eight pony pregnancies were allowed to continue to term.

3. Results

Fourteen of the 15 pregnancies appeared unaffected. One pony mare whose pregnancy appeared unaffected at four days after treatment had ended was found to be not pregnant six days later. Serum progesterone concentrations all remained within the range of normal for early gestation. The mare’s baseline progesterone concentration was lower than any other mare and significantly lower than the mean of five other pony mares whose gestation was within six days (5.48 vs. mean of 16.01±4.1SD, P < 0.01). The eight mares allowed to carry to term delivered without complications. All neonatal musculoskeletal, neurologic, and cognitive measures were within normal limits.

4. Discussion

These results suggest a relatively low risk of disruption of early-gestation pregnancy or adverse effects on foals following GMCOMR and not different (P > 0.10) from gender-matched control foals during the same time frame within the herd.

Acknowledgments

Funds and facilities for this project were provided by the Raymond Firestone Research Trust Grant and the Dorothy Russell Havemeyer Foundation.

Conflict of Interest

The Authors declare no conflicts of interest.

Reference

1. Jacobsen CC, Sertich PL, McDonnell SM. Mid-gestation pregnancy is not disrupted by a 5-day gastrointestinal mucosal cytoprotectant oral regimen of misoprostol. Equine Vet J 2013; 45:91–93.