An intrauterine device with potential to control fertility in feral equids.

This research article discusses a pioneering pilot study conducted to test the effectiveness of a hormone-free intrauterine device (named iUPOD) in controlling the fertility of feral equids or wild horses. The study suggests that the iUPOD effectively prevents pregnancy in mares without disrupting their hormonal cycles and fertility returned once the device was removed.

Study Design and Sample

• The study was a four-month-long pilot program that incorporated eight mares. The mares were given the iUPOD device at different stages of their estrous cycle.
• Following the insertion of the device, the mares were put in a paddock with a stallion and kept together for 120 days.

Methodology and Results

• The researchers used a handheld magnetic detector wand to non-invasively identify the placement of the iUPOD inside the mares’ uterus on a weekly basis.
• Additionally, transrectal ultrasonography was performed on the mares on pre-arranged days. This was done to assess the number and size of follicles and corpora lutea, as well as to determine if there was intrauterine fluid (IUF) present.
• Furthermore, the mares and the stallion were observed daily to note down any mating behavior. Also, weekly samples were taken to study progesterone levels.
• The results showed that none of the mares became pregnant while the iUPOD was in place. After removal of the device, two out of four mares conceived within 30 days.
• Note was also taken of progesterone levels during the experiment. Three out of eight mares exhibited periods of greater than 14 days where progesterone concentrations were less than 1 ng/mL, while seven of the eight mares showed periods of greater than 14 days with progesterone concentrations above 1 ng/mL.
• An interesting finding was the marked presence of biofilm on the devices of two mares at the time of device removal.

Conclusions

• This study constitutes significant progress towards the non-hormonal control of fertility in wild horses. By utilizing the iUPOD device, a substantial decrease in fertility was noted among the selected sample of mares. The device was found to be non-invasive and did not seem to affect the natural hormonal balance of the animals significantly.
• The study also indicates that fertility was restored in a number of mares upon removal of the device, showing its potential as a reversible contraceptive method.
• The study has implications for controlling the growth of horse populations in the wild, which could have biodiversity and environmental implications.