Reproduction Clinic

Embryo Transfer Candlewood Equine offers an embryo transfer/recovery program which covers all aspects of embryo transfer from breeding to pregnancy. Embryo transfer is a breeding procedure in which a 6-8 day old embryo is flushed out of one mare’s uterus, and transferred to another mare’s uterus. The surrogate or recipient mare then carries the foal to term. Let us help you with your embryo transfer program and achieve success. Your goal is our goal …a healthy foal!

Two embryo recovery foals from one donor mare flush

Why do an Embryo Transfer?

• Some mares can no longer carry their own foal to term due to reproductive or physical problems. Valuable foundation bloodlines can be preserved.
• Young fillies that can produce viable embryos but are not yet able to carry them may be used as donor mares.
• Mares that foal too late in the season can have their embryos transferred to another mare to carry, leaving the donor open for early breeding the following year.
• Mares can produce foals without interrupting performance career. Early season and well-timed mid-season transfer can work around race or show schedules.
• Multiple foals can be produced from one mare (possibly genetically superior) in a breeding season.
• Owner’s who do not want their mare to bear the stress of foaling can reduce their stress by having the recipient mare carry the foal.

Is the donor mare at risk in this procedure?

• There is no more risk than that of a standard palpation. The embryo is removed non-surgically by flushing the uterus with several liters of warmed phosphate buffered saline solution with added nutrients and antibiotics. The donor mare should be current on immunizations and in good health.

Is an embryo always recovered?

• We flush three times in a row into a filtered collection dish to be sure that if an embryo is present, it will be recovered. However, if the mare has not conceived, there will be no embryo.

How is the embryo implanted into the recipient?

• Almost all implants are performed transcervically now. A small pipette carrying the embryo is slipped gently through the cervix and into the uterus depositing the fertilized egg.

How long does the donor need to be at the center?

• Less than an hour for flushing unless overnight accommodations are required, as for out of town mares. Once the mare is flushed, she may return to her normal activities.

How soon can the donor be rebred after flushing?

• As soon as she returns to estrus, usually three to five days after the flush. Upon request, we will administer a prostaglandin at the completion of the flush, which destroys the corpus luteum allowing the mare to return to estrus.

How many times can a mare be flushed in one year?

• Research has not shown any limitation, although it is recommended that the mare be allowed to rest for a cycle after every three to four flushes.

Can this procedure be done to a mare with a foal by her side?

• Yes, but the foal heat may have a lower conception rate than that of any subsequent heat cycles.

Who provides the recipient mare?

• Candlewood Equine does not usually supply recipient mares. We prefer to use transfer stations where recipients are synchronized with the donor. These mares are biopsied and carefully screened. We accept only those that are easy to handle, large boned, healthy and breeding sound. We will help you select a recipient facility, process the contracts and arrange the shipping of the recipient mare when confirmed pregnant and ready to travel.

How is the recipient synchronized with the donor?

• When the donor has ovulated, the transfer station will choose a recipient that ovulated the same day, the day before, or up to three days later. They rarely need to synchronize artificially (with drugs) due to the large size of the herd.

What are the chances of a successful transfer?

• Research has shown that embryos will be recovered from between 50% to 75% of the mares flushed, depending on the fertility of the mare and stallion, and that between 65% and 75% of those transferred will result in pregnancy.

What am I as an owner required to do to prepare my mare for an embryo transfer?

• Candlewood Equine needs to be notified when the mare is first bred, and most importantly, when she ovulates. It is very important that palpation is performed daily to ensure that we recover a 7-8 day old embryo. Also, please notify us immediately when she ovulates so that we can arrange an appointment for flushing.

What effect will the embryo transfer have on being able to register the foal?

• Each registry has different rules. Please contact your registry to be sure that you follow their requirements. NOTE: Some registries require advance notification of intention to transfer.

Will the foal inherit any characteristics from the recipient mare?

• No. The foal will only inherit the genetic characteristics of its genetic parents.