Frequently Asked Questions

For those new to embryo transfer (ET) here is a general summary/understanding of the process. Your donor mare is carefully monitored through her estrous cycle and bred at the optimal time to either fresh, cooled, or frozen semen. Her ovulation is confirmed on the basis of ultrasound evaluation and then at approximately seven days post-ovulation the embryo is non-invasively lavaged out of her uterus.  The fluid is then carefully filtered and examined microscopically.  

Once the embryo is identified, and deemed viable, it is transferred into an appropriately synchronized recipient mare’s uterus.  This procedure is done non-surgically through the cervix.  The embryo is then implanted into the recipient mare’s uterus and she will carry the foal to term.

As you can well imagine, many factors enter into the formula for a successful embryo transfer.  The donor mare be teased with a stallion, a uterine ultrasound performed and bred during ovulation. The same factors hold true for the monitoring of the Recipient mare.  This requires daily or optimally twice daily ultrasounds of the donor and recipient mare’s ovaries to determine the precise time of their respective ovulation.

Assuming the donor mare is healthy and reproductively sound, the overall odds of retrieving a high quality embryo are very good.  The recipient mare is an exceedingly important factor in determining the success of the program.  Young and healthy mares with no reproductive problems are an absolute must. Lease or purchase options are available for these mares. 


The Embryo transfer process allows for mares to produce more than one foal per year, for those registries that allow it.  This offers more marketability options of mares, allows for those with vigorous show scheduled to continue competing while producing foals via (ET), and offers possibilities for older or unhealthy mares, that are unable to carry or deliver foals for some reason an avenue to continue reproduction with higher odds for success and live foals.

Additional Resources

Horse Training | Gentle Solutions Dressage

Veterinary & Equine Reproduction | Alamo Pintado Equine Medical Center

Equine Transportation | U.S. Equestrian Services

Recipient Mares | JM Equine Management

Coat Color Calculator | Animal Genetics

Genetic Testing | Etalon Diagnostics or
University of California, Davis

Photography | Elizabeth Hay
or Patty Wilding