Embryo Transfer

Embryo Transfer at Tomlinson Equine

Emma Tomlinson became fascinated in Embryo Transfer in her latter years at Vet school when she spent time in Argentina with some vets over there. She visited Dr Fernando Rieras Embryo Centre, Dona Pilar, and when arriving home in 2002  Beaufort Embryo Transfer was born. In 2018 we decided to merge our two companies into one and we now offer all reproduction and performance vet work under the name Tomlinson Equine. 

Tomlinson Equine has been an established leader in Equine Breeding since starting out, specialising in Embryo Transfer. We are proud to be one of two specialist transfer centres in the UK, boasting high success rates and a very high quality of service for all broodmares, stallions and foals. We believe the success of Tomlinson Equine is due to our team always striving for further improvement, development and continually being on top of new advancing techniques being introduced into the reproduction industry.

Equine Embryo Transfer (ET) is growingly popular across all disciplines. Seen in British Eventing, British Dressage, Polo, British Showjumping, British Breeding and Showing, although Equine Embryo Transfer is not limited to these equine sports. 

To compliment our Embryo Transfer we also offer the option to receive Chilled Transported Embryos this is where an embryo, flushed out of your mare by a suitably competent reproduction vet, is transported to Tomlinson Equine on the day of the flushing and transferred into a perfectly synchronised, suitable recipient mare. In order for this route to be successful both vets need to be able to communicate with each other directly.

A service many may not think possible is Embryo Freezing. Tomlinson Equine has been successfully freezing embryos for a number of years.  This process allows embryos to be collected (by the same process of non-surgical uterine flushing) and instead of being transferred into a recipient mare, the embryo is frozen and can be stored.

What is Equine Embryo Transfer?

Equine Embryo Transfer (ET) is the collection of an embryo (usually 8 days old) from the uterus of a genetically desirable mare (the Donor) and it is transferred into the uterus of a reproductively competent mare (the Recipient) which then carries the pregnancy to term and nurtures the foal until weaning.  The resulting foal’s genetics are derived from the donor mare and stallion (exactly the same as natural breeding); the recipient merely takes the foal from embryo stage, through pregnancy and birth to weaning and has no genetic influence on the foal. 

Why choose Embryo Transfer?

Embryo Transfer (ET) allows one to breed from a high class proven competing mare without interrupting her competition schedule.  Embryo Transfer also allows a breeder to produce more than one foal from a mare in any one breeding season; these multiple offspring can be by the same or differing stallions.   Embryo Transfer is also used to overcome some uterine based infertility, and is also used in mares that are considered too old to carry a pregnancy themselves or too valuable to undergo the risks of pregnancy and foaling.

With many Breeders opting for Embryo Transfer it is important for those who are looking into it to understand its fundamental principles. Embryo Transfer favours breeding from superior quality mares, which in turn improves the standard of British bred Sport Horses.

There are many advantages of this increasingly popular breeding technique are numerous and include: –

  • The ability to breed from a top performing mare while she is competing.  Embryos can be flushed from a mare whilst she is training & competing. At Tomlinson Equine we offer walk in and residential Embryo Transfer, providing you with options to keep your breeding program as flexible as possible to fit around your mare. 
  • Obtaining multiple foals in a single breeding season from a valuable and proven dam. This allows you to use more than one stallion on your mare in the breeding season, and also maximising breeding potential.
  • Avoiding the risks of pregnancy and foaling in a priceless mare.
  • Overcoming uterine based infertility. Embyro Transfer allows you to breed with a top quality mare who may have had difficulty carrying in the past.

The process and how to start

All mares must be booked in with us before they arrive at the centre.  This involves the completion of a Booking Form and returning it to the office with a deposit on the admission fee.   

Before a mare arrives at the centre, she must have negative results for CEM, EVA, EIA and Strangles Blood.  These are routine reproductive tests, and samples can be taken by your vet and sent to the lab for testing.  Results usually take around 3-4 days to come back from the lab (depending on the lab used).   We advise that samples are taken around 14 days before the mare is intended to arrive at the centre.  Please take note of specific health requirements for all horses coming to the centre.

2. Admission & Insemination

Once the mare arrives at the centre her cycle is closely monitored by routine ultrasound scanning of her ovaries and uterus so the insemination can be carried out at the optimum time.  If a mare is only coming for a walk in flush, she will be monitored by your own (reproductively competent) vet, who will need to liaise closely with us about the mare’s cycle in order that we can synchronise recipients accordingly.  

3. Flushing  

Around 8 days post ovulation, the mare undergoes a non-surgical uterine flushing.   The donor mare is usually lightly sedated during the flushing; she stands very comfortably and happily during the process.  The flushing medium passes through a very fine filter and the resulting fluid is examined under a microscope for the presence of an embryo.  The donor mare is not signed off the embryo transfer program until post-flushing scans have confirmed that the uterus is in a good condition and she is coming back into season / cycling correctly.   Some donors remain at the centre for further embryo transfer cycles, or the donor mare can leave the centre when she has been reproductively signed off by a vet.

4. Transfer

Embryos are handled in a very clean and sterile way. The embryo is washed and transferred into a small straw, which is then put into a transfer gun.  Using the transfer gun, the embryo is placed into the uterus of a suitably synchronized recipient mare.

5.  Pregnancy

The recipient mares are pregnancy checked initially at around 15 days then at regular intervals so we can monitor the progress of the pregnancy closely.  

6.  Leaving the centre

Once the recipient mare has been confirmed 42 days in foal, she is free to leave the centre and go home with the owner of the pregnancy she is carrying. Pregnant recipients are kept by the owner of the foal they are carrying until the foal is weaned, at which point the recipient mare returns to the centre.  Alternatively, recipient mares can remain at the centre on a longer term basis and stay with us to foal down.  

Chilled Transported Embryos

We also offer a Transported Chilled Equine Embryo service, where Tomlinson Equine accepts an embryo which has been flushed out of your mare by a suitably competent reproduction vet and is transported to Tomlinson Equine’s Centre on the day of the flushing and transferred into a perfectly synchronised, suitable recipient mare. 

Freezing Equine Embryo’s

This process has been used by breeders for a variety of different reasons and in many enables the genetics of a successfully well bred mare to live on through the embryo when a suitable stallion is found. Tomlinson Equine has extensive experience in freezing equine embryos. The process is the same as the above  (by the same process of non-surgical uterine flushing), however instead of being transferred into a recipient mare, the embryo is frozen and can be stored.