IUDs For Mares:
Frequently Asked Questions
Wait, we have IUDs for horses?
Yes! They are very new! Research and development for this product (called the iUPOD) was conducted between 2013 and 2018, and the device was announced in 2019. It was only made commercially available this year (2021).
What is an IUD for a mare?
IUDs (intrauterine devices) for mares are a bit different than IUDs used in humans. One difference is that the equine IUD does not contain any hormones. Another difference is in the size, shape, and material of the device. The iUPOD is made of three smooth, elliptical shaped, coated magnetic units that self-assemble into a ring shape once inserted into the mare’s uterus. Each unit is about the size of a lima bean. The units will stay inside the uterus in this configuration, preventing the mare from coming into heat until they are removed.
iUPOD units before insertion
How does the iUPOD work?
The presence of the device inside the uterus acts locally on the endometrium (uterine lining) to prevent her from cycling. There are no hormones in the device.
How is the iUPOD placed?
In most mares, the three iUPOD units are inserted into the mare’s uterus through a small tube inserted vaginally and through the cervix, much like artificially inseminating a mare.
insertion of the iUPOD units
Does placing the IUD hurt the mare?
Most mares will not experience any discomfort when the IUD is placed. The procedure is similar to breeding with artificial insemination. If the mare is young, or a maiden (has never had a foal/ never been bred), she may experience brief, slight discomfort (less than 2 minutes). Mares who have not been bred before will most likely be sedated for the procedure, which does provide some relief from discomfort!
How long does the iUPOD last?
It is recommended that the device be removed 5-7 months after insertion. This is based on the mare’s seasonal estrus cycle- most mares cycle only during warm months (usually March to September in our area). The iUPOD is guaranteed for up to one year, so if it’s left in place longer, there is no guarantee of safety or effectiveness from the manufacturer. In most cases, it’s appropriate to place the iUPOD in the spring, and remove it in late Fall or early winter. For mares that cycle year-round, it could be left in place for the year.
How effective is the iUPOD?
In initial studies, over 85% of mares with an iUPOD had extended periods with no heat cycles. Most mares went 60-90 days between heat cycles (compared to 21 days for mares without an iUPOD). When the mares with the iUPOD did come into heat, their behavior was reported to be much better than their behavior when they were in heat without the iUPOD.
Factors that may influence success of the IUD include uterine health, mare age, and timing of insertion. Mares with a healthy uterus (which are often younger mares) are more likely to have good success in preventing heat cycles. It also appears that inserting the device while the mare is in heat may increase the chances that it will work well long-term.
iUPODs inside the uterus, seen on ultrasound
How safe is the iUPOD?
This product appears to be very safe! The biggest risk is the possibility of uterine infection – either from introducing bacteria into the uterus during placement, or worsening a pre-existing uterine infection. We reduce these risks by making sure everything is sterilized, and the mare is cleaned and disinfected before placement.
How is the iUPOD removed?
When it’s time to remove the IUD, the mare is given an injection to bring her into heat (this will open the cervix to make retrieval easier), and another magnet is inserted into the uterus. That magnet will attach to the iUPOD units and is then withdrawn through the cervix, bringing the IUD with it! (Magnets!)
What are the advantages to the iUPOD over other methods of estrus suppression?
Other options for estrus suppression include Regumate (which is messy and can be unhealthy for humans to handle) and hormone injections (which require injecting the horse daily or weekly for a period of time, leading to possible resentment by the horse or injection site soreness).
Will the iUPOD affect my mare’s future fertility and can I breed her after it is removed?
In all of the initial studies of this device, mares had no problems after removal of the device, and all were able to get pregnant on the first cycle after removal.