Interovulatory intervals in mares receiving deslorelin implants in Ireland (2009 to 2010).

This study examines the effect of deslorelin acetate implants, used to induce ovulation in horses, on the length of the estrous cycle in Thoroughbred mares in Ireland and the UK. It found a significant difference in the time between ovulations when the implant was not removed, suggesting it’s better to remove it when possible.

About the Research

• This research is focused on the application and impacts of deslorelin acetate implants in mares. Deslorelin is a synthetic hormone used to prompt ovulation in horses.
• The study was designed to assess how these implants affected the length of the oestrous or reproductive cycle in Thoroughbred mares based in Ireland and the UK.
• The analysis relied on retrospective data collected from 88 oestrous cycles.

Main Findings

• There was a noticeable disparity in the interovulatory intervals, which is the time between ovulations, in mares where the deslorelin implant was not removed post-ovulation.
• This difference was statistically significant, meaning there is a high likelihood that it is representative of the true effect rather than occurring by chance.
• The results suggest that removing the implant after ovulation is a recommended practice to ensure normal interovulatory intervals.

Comparative Perspectives and Practical Implications

• Previous studies in the United States pointed to the association of deslorelin implants with extended interovulatory intervals, leading to the practice of removing these implants after ovulation.
• The delay in subsequent ovulations observed in this study was less pronounced than those reported in American research, possibly indicating geographical variations in how mares respond to this treatment.
• This study provides valuable information for breeders when scheduling subsequent breeding instances for mares that have been treated with a deslorelin implant in the previous oestrous cycle.
• Furthermore, the results may help to address concerns about long delays in mares’ return to the oestrous cycle, if the deslorelin implant is not removed.