McGee Equine Clinic has a strong interest and expertise in equine reproduction. Dr. Greene completed a rigorous two year residency in equine reproduction, and passed the certifying exam, becoming a board certified specialist. During her specialty training she worked extensively in all facets of equine reproduction including estrus cycle management for breeding and synchronization, artificial insemination with fresh, cooled shipped, and frozen semen, pregnancy management, breeding soundness evaluations of mares (including uterine culture and biopsy) and stallions, embryo transfer, reduction of twin pregnancy, foaling management and assistance, dystocia, and post-foaling exams.

McGee Equine Clinic currently offers the following reproductive services:

  • Ultrasound and palpation per rectum
  • Estrus cycle management and manipulation
  • Uterine culture and biopsy
  • Pregnancy diagnosis via ultrasonography
  • Twin reduction
  • Management of the pregnant mare
  • Artificial insemination with cooled or fresh semen
  • Pre-foaling examinations and vaccines
  • Post-foaling examinations
  • Dystocia Management
  • Management of post-foaling diseases
  • Neonatal examinations
  • Examinations of sub-fertile mares
  • Examinations for reproductive abnormalities including GCT or other cancer

So you have decided you want your mare to have a foal, congratulations! Although it would seem like a simple process-just put the mare and stallion together and wait for the foal in 11 months, in reality breeding management is much more involved, for many reasons. Modern breeding typically involves utilizing a stallion who is chosen for his pedigree, performance, personality, color, or genetics. Often, these stallions are located far away, in distant states or even different countries, which necessitates breeding via artificial insemination.

Pre-Breeding Considerations:

When you first decide to breed your mare there are a few things to consider.

  1. First, is when you would ideally like your foal to be born? Remember, that mares have a gestation length of approximately 11 months, so if you would like to have a May foal, then your mare needs to conceive in June. Keep in mind that because of a roughly 21 day inter-ovulatory interval, if she takes several cycles to conceive, this foaling date will creep correspondingly toward summer. So, if an early foal is important to your breeding program, start planning early!

    For those of you who wish to produce early foals, it is important to recognize that mares are seasonally polyestrus, meaning that most mares at this latitude have predictable fertile cycles in the summer months (during longer daylight hours) but experience “transitional heat cycles” in the fall and spring months and have a period of winter anestrus (no heat cycles/ovulations). Transitional heat cycles that occur in the late winter/early spring are characterized by hormonal, follicular and behavioral fluctuations that may look like the real thing but do not culminate in ovulation and are therefore infertile. To achieve a fertile heat cycle earlier in the year, we can “trick” a mare into establishing a regular cyclic pattern by placing her under lights. If your goal is to start breeding your mare in mid February, she should be started under lights by December 15th. The best way is have a timer set to deliver added light during the evening hours, still allowing overnight darkness to occur. A 100 watt bulb for a 12×12 stall, producing a total of 14-16 hours of total daylight time (lights on from dusk to 10 or 11 pm), should be started 45-60 days prior to her first anticipated breeding attempt. If you plan on starting in April, when a mare is likely ending the transitional phase on her own, lights are probably unnecessary.
  2. Second, is your mare a good candidate for breeding? The best way to determine if she is a good candidate is to have a breeding soundness examination performed by one of our veterinarians. A breeding soundness examination involves a history of past reproductive performance, a general physical examination, and an internal examination of her reproductive tract, including palpation and an ultrasound exam. This allows gathering of a database of information about your mare that can help determine if she is likely to have a reasonable expectation of success with artificial insemination. This examination also allows identification of risk factors that may warrant further diagnostics (such as uterine culture and/or endometrial biopsy) to help assess her suitability. Fertility can be affected by anatomy, age, previous reproductive history/ problems and overall health issues. Your mare should be current on vaccinations, deworming, dental care, hoof care and be in good body condition prior to embarking upon breeding attempts.
  3. Details about the Stallion. Once you have selected the stallion, please contact the stallion’s breeding manager for additional information. It is helpful to inquire about your chosen stallion’s success with shipped cooled semen, you can specifically ask about his first cycle pregnancy rates for the last season, and the average number of cycles per pregnancy. For example, a stallion with a first cycle pregnancy rate of 60% with shipped cooled semen may produce a pregnancy in your mare in a fewer number of attempts (defined as insemination during one cycle) than one with a 30-40% rate. Bear in mind that many factors come into play when determining this number. He may get most mares pregnant in 1-2 cycles, but it still may take your mare 3 attempts to achieve a pregnancy. In addition to his inherent fertility, the mare population that he ships to (young/maiden versus older or problem) can greatly impact his percentages.

    You also need to closely examine all the details of your stallion contract. Beyond the stud fee, how many collections (shipped cooled) or doses (frozen semen) are provided? What will be the additional costs to you for multiple cycle attempts? What are the collection days/times, methods of shipment available (FedEx, counter-tocounter) and notification rules? What is his season? Does he have any dates when he is unavailable (planned shows, for example)? Do they give priority to in-house mares? These questions all address the availability of semen when your mare needs it. All of these factors will help decide how your mare should be managed and when you should start getting her ready.

Cycle Management

When mares are bred by live cover, owners and managers are able to tell the correct time to breed the mare, by relying on her to display signs of estrus (heat), which is the most fertile time in the mare’s cycle. Signs of heat when presented to a stallion include interest in the stallion, squatting, tail raising, urinating, and winking (everting the clitoris). However, in many cases, there is not a stallion on a farm, so many owners do not know when their mare is in heat. The longevity of the semen is the main factor at work here. Best pregnancy rates are produced when viable spermatozoa are already in the mare’s reproductive tract at the time of ovulation. Shipped cooled semen has an expected viability of approximately 48 hours.

In order to ensure that your mare is inseminated at the appropriate time, we will work together to closely monitor your mare. This typically requires multiple exams, including internal ultrasound, to monitor the changes in her reproductive tract that help predict the timing of ovulation and determine when to order semen. Often we will use hormonal manipulation to help encourage your mare to ovulate at the “right time” and help avoid needing more than one semen shipment per cycle.

*One note about ordering semen: we always have our mare owners be responsible for picking up and storing the semen container until the time of insemination. Stallion managers ship semen via many different carriers, and in many different containers. We have found the best success when one person (the mare owner) is responsible for the semen, and ensures it’s safe passage to your location. Please do NOT send your semen to our home address. We are usually out on the road, and not home, and can not guarantee appropriate conditions for the semen.*

Aftercare of your mare post insemination should include an ultrasound exam on the next day to confirm ovulation and check for intrauterine fluid. If the mare has not ovulated, the decision to order more semen for this cycle can be made if appropriate. The presence of intrauterine fluid the next day may indicate a problem with persistent mating induced endometritis. Intrauterine deposition of semen, whether from live cover or artificial insemination, causes a normal, transient inflammatory response within the uterus. Persistence of this inflammation, detected as excessive fluid on ultrasound exam, is detrimental to embryonic survival and can be a significant cause of an apparent failure to conceive. Fertilization of the equine ova (egg) occurs in the oviduct (fallopian tube), with the embryo descending into the uterus 5-6 days post ovulation/fertilization. This creates a window of time during which the mare’s uterus may be treated for problems, such as persistent mating-induced endometritis, which can help maximize your chances of pregnancy in mares determined to be at risk for early embryonic loss.

Pregnancy Examinations

We perform the first ultrasound looking for pregnancy at 14-15 days when the embryonic vesicle is larger and easier to distinguish. If your mare has a history of twins or multiple ovulations, multiple early pregnancy exams may be recommended to help identify the presence of twins. Twin pregnancies are not recommended to be allowed to go to term because the majority result in the loss of both fetuses as a late-term abortion and may be a threat to the mare’s future fertility or life. Early detection of twins allows the option of manual twin reduction, which is most successful between days 16-19 of pregnancy. A subsequent ultrasound examination to detect the presence of an embryo with a heartbeat is typically performed between day 25 and day 30. Depending upon stallion contract requirements or risk factors present in your mare, additional pregnancy monitoring may be recommended by your veterinarian. We also suggest one pregnancy check in the fall, to ensure that the pregnancy has not been lost before the winter.