Preliminary study of the contraceptive effect of a self-assembling intrauterine device (iUPODs) in mares maintained in a paddock with a fertile stallion.

This research paper explores the use of a novel intrauterine device (named iUPOD) for horse contraception, and demonstrates its effectiveness under natural breeding conditions when managed by veterinary professionals with no prior experience with the device. The study represents an encouraging step towards the management of horse and burro populations, particularly in relation to free-roaming populations on Western Public Lands in the USA.

Context of the Study

• The study is driven by a pressing need to find effective methods for controlling the populations of free-roaming horses and burros in the US Western Public Lands.
• Such methods of population control ideally include contraception and sterilization. This research paper focuses specifically on contraception, examining the effectiveness of an intrauterine device named iUPOD (intrauterine POD).

Design and Execution of the Study

• For the research, six mares were selected and each one had an iUPOD administered.
• These mares were then housed continuously with a fertile stallion over a 91-day period to simulate natural breeding conditions.
• Importantly, the use of the iUPOD in this study was managed by veterinary professionals who had no prior experience with the device itself, assessing its usability in real-world situations.

Research Findings

• The study found that the retention and contraceptive efficacy of the iUPOD device was 100%. This means that all the administered devices stayed in place for the duration of the study, and none of the mares became pregnant.
• However, changes in the reproductive cycles were observed. Two of the mares presented prolonged corpus luteum function after the device insertion, one for 37 days and the other one for 91 days. For the rest of the mares, the length of the diestrus phase during their estrous cycles averaged 7.8 days.
• The device was also found to be reversible: four out of the six mares (67%) successfully became pregnant when they were exposed to the same stallion in the following year after iUPOD removal.

Implications of the Study

• The findings demonstrate that iUPOD could be an effective, practical, and reversible means of controlling the fertility of free-roaming horses and burros.
• The research provides promising implications for animal population management, particularly in contexts where free-roaming animal populations need to be responsibly controlled.