Equine Reproduction

• Artificial insemination (AI) in mares can be highly successful, with pregnancy rates varying depending on the type of semen used and overall reproductive management. When fresh semen is used, pregnancy rates typically range from 60–75% per breeding cycle. Success is highest when the mare is reproductively healthy, ovulation is closely monitored by ultrasound, and insemination is accurately timed. Under these conditions, fresh semen AI produces pregnancy rates comparable to those achieved with live cover in most mares.

• When cooled semen is used, expected pregnancy rates are slightly lower, averaging 50–65% per cycle. Outcomes depend heavily on semen quality, proper cooling and handling techniques, and minimizing shipping time, ideally to less than 24 hours. Precise ovulation timing remains critical to achieving optimal results with cooled semen.

• Frozen semen AI typically results in pregnancy rates of approximately 40–55% per cycle. These rates are lower due to the reduced lifespan of frozen–thawed sperm, which requires very precise insemination timing. Pregnancy outcomes with frozen semen can be improved through advanced techniques such as deep-horn insemination and by working with an experienced equine reproductive management team.

• Regardless of semen type, several factors influence the success of artificial insemination. Mare age plays a significant role, with pregnancy rates declining in mares over approximately 12-15 years of age. Uterine health, reproductive history, semen quality, accuracy of ovulation timing, and the mare’s ability to clear post-breeding uterine fluid all contribute to overall success.

Embryo transfer (ET) can be a highly effective breeding option when both donor and recipient mares are well managed. On average, 60–80% of breeding cycles result in successful embryo recovery from donor mares - this can depend greatly on the semen type being used. Recovery rates tend to be highest in young, fertile donor mares with well-timed ovulation and lower in older mares or those with underlying fertility challenges. Once an embryo is transferred, pregnancy rates in recipient mares typically range from 65–80% per transfer, depending on the quality and health of the recipient mare, accurate synchronization with the donor, and proper embryo handling and grading. When all stages of the process are considered—including ovulation, embryo recovery, successful transfer, and early pregnancy maintenance—the overall likelihood of achieving a live pregnancy per donor cycle is approximately 40–60%.

Yes. We closely monitor the mare’s cycle using teasing and ultrasound to accurately time breeding in an effort to only breed once. All breedings are performed by hand, with both the mare and stallion handled on lead ropes and the mare properly restrained. This controlled approach prioritizes the safety of the horses and handlers while ensuring optimal breeding conditions.

• Stallion fertility evaluation typically includes a breeding soundness exam, semen collection and analysis, assessment of libido, and examination of reproductive anatomy to determine breeding potential.

• Mare fertility evaluation may include transrectal ultrasound, uterine culture and cytology, endometrial biopsy, and hormonal assessment when indicated. These tests help identify issues that may affect conception or pregnancy maintenance.

Mares can be bred as early as 2–3 years of age; however, it is recommended to wait until a mare is fully mature—typically around 4 years old or older—to reduce the risk of complications and support an easier pregnancy and foaling. Many mares can continue to produce healthy foals into their late teens or early 20s, though fertility naturally declines with age. This decline is more pronounced in older mares that have never been bred (maiden mares). A mare’s overall health, physical maturity, and reproductive history all play important roles in determining the ideal breeding age. We can perform a thorough pre breeding exam and give our best recommendations based on your individual mare.

We use transrectal ultrasound to closely monitor follicular development and accurately time ovulation. When appropriate, we will include hormonal management to ensure a timely ovulation and maximize the chances of conception.

The length of stay depends on where your mare is in her reproductive cycle at the time she arrives. Ideally, heat cycles are monitored at home and the mare is brought to our clinic shortly before or as she is coming into heat. In this situation, mares typically stay 3–4 days prior to breeding and an additional few days afterward so we can monitor ovulation and ensure an appropriate post-breeding response. In total, 5-8 days for the entire process.

Pregnancy can typically be confirmed by ultrasound as early as 12 days post-ovulation. Early diagnosis (12-16 days post ovulation) allows for detection and management of twins, which can create a high risk situation in mares.

Twin pregnancies in mares are rarely successful and pose serious risks to both the mare and foals. Often, the mare will abort both pregnancies later in gestation and if carried to term, can increase chances for a dystocia (difficult birth) and stillbirths. Early twin reduction significantly improves the likelihood of a healthy, full-term pregnancy.

Yes. We offer secure long-term storage for frozen semen and embryos in monitored cryogenic tanks. All stored reproductive material is carefully labeled, tracked, and maintained under strict quality-control protocols, with storage and release managed according to owner authorization.

Yes. As long as your stallion has good ground manners and is comfortable in new environments and with different handlers, he can typically be trained for collection. Each stallion is unique; however, most require 2–4 training sessions to become comfortable mounting the phantom. Once trained, we evaluate semen quality to determine whether it is suitable for fresh shipment and/or freezing. The entire process generally takes 5 days to 2 weeks, depending on the individual stallion.