Equine Embryo Transfer
Embryo transfer (ET) is the process of removing an early pregnancy from one individual and putting it into another.
Although this may seem unnatural, there are many good reasons in animal reproduction for doing this. It enables a breeder to reproduce a valuable animal without putting them out of commission for the months it takes to go through a pregnancy and raise the baby. It allows many otherwise infertile or sub fertile individuals to produce a pregnancy, and delegate the hard work of actually maintaining the pregnancy and raising the foal to another individual. It allows a mare with health or lameness issues to produce another foal without putting the mare through the stress of pregnancy. It also allows us to produce several foals in one breeding season from one valuable mare. My first experience in doing ET was to do exactly that; we produced 9 foals in one year from one mare. Additionally, it is a much safer way to produce a foal from a mare that you could not bear to lose. Pregnancy is actually one of the most dangerous things we ask our animals to go through; embryo transfer allows us to produce foals from valuable animals without putting them through the danger of pregnancy.
Over the past few years, ET has evolved from a technically difficult and complicated procedure, to a procedure that can be reliably offered in a clinical setting. Costs have gone down to where it is affordable to most horsemen. Success rates with fertile mares and stallions can be within a few percentage points of natural breeding, or conventional artificial insemination.
The ET process begins like any other pregnancy. The donor mare should have a breeding soundness evaluation to evaluate her ability to ovulate and produce a fertilized embryo; if she has fertility issues, they should be addressed prior to breeding. She needs to be monitored during her cycle and bred as close to ovulation as possible to increases the odds of pregnancy, as in any other managed breeding.
The embryo is then flushed out with a special fluid using a balloon catheter inserted into the uterus about 7 days after ovulation; the embryo is washed and processed in a different medium, then inserted into a “recipient” mare’s uterus through a special pipette.
The tricky part of ET is having a recipient mare available at the proper time; the recipient mare needs to be synchronized with the donor. Best results are achieved when the recipient mare has ovulated within the narrow window between 1 day before the recipient mare, to 2 days after.
The majority of work for the veterinarian performing the procedure is in determining the time of ovulation of the donor and recipient mares. The donor mare and the recipient mares need to be examined with ultrasound daily near the time of ovulation to determine exactly when they ovulate; this determines which mare will be suitable as a donor, and on what day the procedure will be done. We generally do our transfers exactly 7 days after the donor ovulates; day 7 embryos are large enough to easily find, and still small enough to survive the manipulations required to perform the transfer.
If you have access to your own mares, they can be synchronized with the use of various hormones to ovulate near the same time as the donor; this is a good option, and generally less expensive than option 2. Option 2 is to buy or lease a mare that is at the right stage of her reproductive cycle from a facility that keeps and maintains recipient mares.
If you choose to synchronize your own mares, we set you up on a schedule where you give the donor mare and recipient mares an oral dose of a progestin compound daily for 10 days, and on the 10th day you give each mare a dose of a prostaglandin. If they respond as planned, they should all come into heat between 3-5 days after the injection is given, and ovulate from 7-10 days post injection.
In summary, embryo transfer is now an affordable and attractive method to produce foals, and one that you might want to consider. If interested, please contact Rustebakke Veterinary Service for more details at 509-758-0955, or e-mail us at clinic@rvsvet.com.
Although this may seem unnatural, there are many good reasons in animal reproduction for doing this. It enables a breeder to reproduce a valuable animal without putting them out of commission for the months it takes to go through a pregnancy and raise the baby. It allows many otherwise infertile or sub fertile individuals to produce a pregnancy, and delegate the hard work of actually maintaining the pregnancy and raising the foal to another individual. It allows a mare with health or lameness issues to produce another foal without putting the mare through the stress of pregnancy. It also allows us to produce several foals in one breeding season from one valuable mare. My first experience in doing ET was to do exactly that; we produced 9 foals in one year from one mare. Additionally, it is a much safer way to produce a foal from a mare that you could not bear to lose. Pregnancy is actually one of the most dangerous things we ask our animals to go through; embryo transfer allows us to produce foals from valuable animals without putting them through the danger of pregnancy.
Over the past few years, ET has evolved from a technically difficult and complicated procedure, to a procedure that can be reliably offered in a clinical setting. Costs have gone down to where it is affordable to most horsemen. Success rates with fertile mares and stallions can be within a few percentage points of natural breeding, or conventional artificial insemination.
The ET process begins like any other pregnancy. The donor mare should have a breeding soundness evaluation to evaluate her ability to ovulate and produce a fertilized embryo; if she has fertility issues, they should be addressed prior to breeding. She needs to be monitored during her cycle and bred as close to ovulation as possible to increases the odds of pregnancy, as in any other managed breeding.
The embryo is then flushed out with a special fluid using a balloon catheter inserted into the uterus about 7 days after ovulation; the embryo is washed and processed in a different medium, then inserted into a “recipient” mare’s uterus through a special pipette.
The tricky part of ET is having a recipient mare available at the proper time; the recipient mare needs to be synchronized with the donor. Best results are achieved when the recipient mare has ovulated within the narrow window between 1 day before the recipient mare, to 2 days after.
The majority of work for the veterinarian performing the procedure is in determining the time of ovulation of the donor and recipient mares. The donor mare and the recipient mares need to be examined with ultrasound daily near the time of ovulation to determine exactly when they ovulate; this determines which mare will be suitable as a donor, and on what day the procedure will be done. We generally do our transfers exactly 7 days after the donor ovulates; day 7 embryos are large enough to easily find, and still small enough to survive the manipulations required to perform the transfer.
If you have access to your own mares, they can be synchronized with the use of various hormones to ovulate near the same time as the donor; this is a good option, and generally less expensive than option 2. Option 2 is to buy or lease a mare that is at the right stage of her reproductive cycle from a facility that keeps and maintains recipient mares.
If you choose to synchronize your own mares, we set you up on a schedule where you give the donor mare and recipient mares an oral dose of a progestin compound daily for 10 days, and on the 10th day you give each mare a dose of a prostaglandin. If they respond as planned, they should all come into heat between 3-5 days after the injection is given, and ovulate from 7-10 days post injection.
In summary, embryo transfer is now an affordable and attractive method to produce foals, and one that you might want to consider. If interested, please contact Rustebakke Veterinary Service for more details at 509-758-0955, or e-mail us at clinic@rvsvet.com.
