With the support of partner studs we are now pleased to be able to offer our clients an embryo flushing service. Embryo transfer (ET) is in essence a pathway for surrogate pregnancy.

What is embryo flushing?

This is a procedure where the pregnancy is non-surgically flushed from your mare between day 7-9 following ovulation so she does not carry her own pregnancy.

The flush is performed at our hospital as an outpatient procedure. It does not usually take longer than an hour and so only light sedation (if any) is required. Any embryo that is present is collected in a small filter. This filter is searched under a microscope. If any embryo is identified it then needs to go through a small processing procedure known as washing. Once the embryo has been prepared it can then be shipped. The donor mare (the one that has been flushed) recieves a prostaglandin injection, this brings her into season again straight away in order to prevent any infection being introduced as a result of the procedure. She will have one further scan a few days after the flush in order to ensure her reproductive tract has recovered from the procedure as expected. 
The embryo is shipped to our partner stud where it is transferred into a recipient mare.
Once pregnancy is confirmed you will lease the recipient mare carrying your pregnancy until the foal is weaned. There is no way to confirm pregnancy prior to performing the flush, so the flush is performed each time the mare is bred and declared positive or negative at the time.

When should embryo transfer be considered?

This technique is an attractive repro solution for sports horse breeding. It enables mares to breed at an age rather than waiting until they are retired.

What are the benefits of embryo transfers?

• This option means breeding can be facilitated when your mare is younger and therefore more likely to be reproductively successful.
• There is minimal impact on available competition time as your mare does not have to carry the pregnancy or nurse the foal.
• This technique facilitates the option of more than one pregnancy per mare, per year and maximises the potential for horses of high genetic value 
• Mares with health conditions preventing them from holding pregnancies can still have offspring

What are the success rates for equine embryo transfer?

Our positive flush rate is similar to the mare's normal conception rate, around 60%. Once an embryo is retrieved, it has an 80% chance of being successfully transferred into the recipient mare (first positive pregnancy test usually around 4 days after transfer). This figure is comparable in embryos that are transferred immediately and those that are shipped same day via a transported embryo service as provided by us. 

Where does the equine embryo transfer take place?

Embryo transfer is performed at RVC only but is done within an hour and the owner is welcome to be present. The reason it can only be done at RVC is due to access to facilities to ensure if an embryo is retrieved it can be treated and processed for transfer in the cleanest way possible with the least risk of harm.

Can I supply my own recipient mare to carry the pregnancy?

Unlike many other species, synchronising the donor and the recipient mare together to ensure a successful transfer is very challenging and often requires a minimum of 3 potential recipients to be lined up. This means we only work with partner commercial studs that lease out recipient mares from a professional herd to avoid any last minute panic when a recipient is suddenly no longer available or suitable. In the future we hope to be able to offer an in-house transfer programme where embryos can be frozen and stored, which will allow us to use clients' own recipient mares. 

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