Article Text

other Versions

Interovulatory intervals in mares receiving deslorelin implants in Ireland (2009 to 2010)
  1. I. S. F. Henderson, BVSc, MSc, Cert, EM (StudMed), DECEIM, MRCVS1,
  2. P. Brama, DVM, MBA, PhD, DECVS, DRNVA2,
  3. M. Osborne, MVB, Cert ESM, MRCVS1 and
  4. M. E. Beltman, DVM, PhD, DECAR3
  1. Forenaghts Stud, Naas, Ireland
  2. Veterinary Clinical Studies, School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
  3. Herd Health and Animal Husbandry, School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
  1. E-mail for correspondence imogenjennie{at}

Deslorelin acetate implants, recently licensed in Ireland and the UK for ovulation induction in mares, have been associated with prolonged interovulatory intervals in USA studies, leading to the practice of removing implants postovulation. Trial data in Australia indicate a less pronounced effect on interovulatory intervals, suggesting possible geographical variation. Objectives of the current study were to assess the effect of deslorelin implants, with and without removal on oestrous cycle length in Irish- and UK-based Thoroughbred broodmares. Data were collected retrospectively from 88 oestrous cycles. A statistically significant difference (P=0.02) was found between interovulatory intervals in mares in which the deslorelin implant was not removed, compared with administration and removal of the implant or the use of human chorionic gonadotrophin. The results suggest that implant removal when possible is advisable. The delay in subsequent ovulations was less marked than that reported in some studies from the USA. This information is useful in deciding when to schedule subsequent breeding for mares which received a deslorelin implant during the previous oestrous period and provides evidence to counter-concerns that mares treated with deslorelin implants may experience a long delay in return to oestrus if the implant is not removed.

Statistics from


  • Ms Henderson was also at the School of Veterinary Medicine, University College Dublin throughout the duration of the study; her present address is Newmarket Equine Hospital, Cambridge Road, Newmarket, Suffolk CB8 0FG, UK

  • Provenance not commissioned; externally peer reviewed

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.