Efficacy of Human Chorionic Gonadotropin to Induce Ovulation in the Mare when Associated with a Single Dose of Dexamethasone Administered at Breeding Time

1. Introduction

Human chorionic gonadotropin (hCG) and dexamethasone have a role in the reproductive management protocols of mares susceptible to persistent matinginduced endometritis. The value of the combined administration of hCG and dexamethasone has recently been questioned in a study by Ferris and McCue (2010) reporting a high rate of ovulatory failure in mares treated with dexamethasone. The present retrospective was performed to determine if a 50-mg injection of dexamethasone at the time of breeding would interfere with the ability of mares to ovulate at the expected time when treated with hCG. Analysis of the data suggests that dexamethasone at the dosage used has no detrimental effect on the expected ovulation timing of mares treated with hCG.