[Show abstract][Hide abstract] ABSTRACT: Human chorionic gonadotropin (hCG) and dexamethasone have a role in the reproductive management protocols of mares susceptible to persistent mating-induced endometritis (PMIE). However, it is possible that there is interference between these 2 drugs.
The objective of this retrospective study was to determine the efficacy of hCG to induce ovulation in mares treated with dexamethasone at breeding time.
Medical records from 152 mares and 223 cycles were analysed. In 113 cycles, mares susceptible to PMIE were treated with 1500 iu hCG and a single dose of 50 mg dexamethasone, 110 cycles were used as controls and subsequent ovulation was assessed ultrasonographically and compared.
Dexamethasone did not inhibit ovulation in mares susceptible to PMIE.
Multiple administrations of dexamethasone to mares in early oestrus have induced ovulation failure. However, a single dose of dexamethasone, administered at breeding time, has been used as an effective modulator of PMIE in susceptible mares and does not interfere with efficacy of hCG to induce ovulation.
[Show abstract][Hide abstract] ABSTRACT: The present study describes the effect of a single dose of dexamethasone administered to mares at time of breeding. In an initial experiment, the authors investigated safety of treatment. In a second experiment the effect of treatment on the uterine environment, fetal development and pregnancy outcome was examined. In the final part of the study, mares susceptible to persistent mating induced endometritis were identified, by means of a risk factor score system and the effect of treatment evaluated. Results indicated that dexamethasone administered at breeding time did not negatively impact on mares medical and reproductive traits. A reduced inflammatory response was observed post-mating in treated versus control mares and mares with multiple risk factors for susceptibility to persistent mating induced endometritis showed improved pregnancy rates following treatment. The authors concluded that a single dose of dexamethasone administered at the time of breeding is safe and can be used to modulate the uterine inflammatory response to breeding in susceptible mares.