The best for your horse July 2014 Part 6! TRACK TO HACK Consolidating the Basics AUSTRALIAN MINIATURE PONIES EMBRYO TRANSFER What you need to know AU$4.95 ISSN 2200-3754 Show Jumping with JEN HAMILTON more inside...
Brought to you by... by Dr Gillian Rickard, BVSc (Hons) equinedentalvets.com.au committed to advancing horse health Embryo Transfer Watch the video at: www.equinedentalvets.com Whether it is to allow a competitive mare to continue performing, achieving multiple foals from one mare in a season or to ensure valuable genetics are not lost if a mare can no longer carry a foal, breeders and veterinarians are recognising the advantages of embryo transfer. In this article, Dr Gillian Rickard from the Illawarra Equine Centre explains the importance of working with an expert team, and the process and factors that play a role in the success of this specialised breeding technique. Embryo transfer (ET) is a procedure where a fertilised egg is removed from the donor mare and put into a recipient mare, who carries the pregnancy to full term and gives birth to a foal which she considers her own. The main reason for doing this is so the donor mare does not have to carry a foal. Originally, the main candidates for ET were older mares who could no longer get or stay pregnant due to uterine problems or who had musculo-skeletal issues which would make carrying a foal or giving birth extremely difficult. As ET has become more successful breeders have recognised the huge advantages of ET. Advantages of embryo transfer Competition mares can produce progeny with minimal time out of work. The ability to get multiple foals out of a single mare in a season. The mare that is unable to carry a foal, but whose genetics or performance makes her progeny valuable. Mares that foal late in the season can still produce a foal for the year through embryo transfer but, by not carrying it themselves, can then make an early entry into the next breeding season. Equine Dental Vets an organisation committed to advancing horse health Our group is made up of Equine Dental veterinarians from across the globe and we have over 300 members right here in Australia. Most of our members provide afterhours and emergency care for all equine health issues and using our dedicated search on our website you can find the Equine dental vets nearest you at the touch of a button. This is particularly useful if you are away from home, for example when travelling to shows and competitions. We are proud to provide you this healthcare information in partnership with Horses and People magazine. Page 12 HORSES and PEOPLE Phone: 07 5467 9796 admin@horsesandpeople.com.au
It is very exciting to retrieve an embryo from a donor mare, but implanting it into a suitable recipient mare is crucial to success. The process The first step is for the donor mare to be inseminated either naturally, with chilled or with frozen semen. Knowing the time of ovulation is very important, so the mare should be scanned throughout her cycle. She should also be monitored and managed for fluid during her cycle and following insemination. The cleaner and healthier the mare s uterus is, the healthier the embryo will be and its chance of sticking in the recipient mare greatly improved. Generally, the flush date is 7 to 8 days postovulation. The earlier day is chosen if the mare is young and the semen fresh or chilled, and the later time if the mare is older and the semen frozen or if previous attempts have been successful on a particular day. Day of flush relates to the size of the embryo and, surprisingly, smaller, younger embryos are less fragile than larger, older ones. If you flush too early, however, the embryo may not yet be released into the uterus and so will be missed. Another possibility is if, at that time, there is no embryo, which will be because the mare has failed to conceive (for various reasons). www.horsesandpeople.com.au HORSES and PEOPLE Page 13
The flush For the flush, the donor mare is put in the crush, lightly sedated, her tail wrapped and her perineum cleaned thoroughly. A Foley type balloon-tipped catheter is passed through the cervix and inflated, which locks the catheter in the uterus. The catheter is attached via y tubing to the pre-warmed embryo flush medium and a filter cup, which will catch the embryo. The fluid flows into the uterus and inflates it. With the help of rectal ultrasound, it is established that the fluid is up both uterine horns. A gentle massage of the uterus encourages the fluid around the uterus and then the fluid is allowed to flow out passing through the filter cup. Between flushes the cup is disconnected and the contents checked for an embryo under microscope. If one is found in the first flush and the mare hasn t had a double ovulation - and hence a chance for a second embryo - then the catheter is removed and the mare can go back out. If, however, the embryo is not there on the first flush, the practitioner will use several more bags of flush to try to retrieve an embryo. The first step in the embryo transfer process is for the donor mare to be inseminated either naturally, with chilled or with frozen semen.. The transfer If an embryo is recovered, it is given a grading based on its size, shape and developmental stage. Whilst the grading is subjective, it does help with predicting the likelihood that the recipient mare will hold the pregnancy. Grade 1 is best and grade 4 is very unlikely to survive. The embryo is washed to remove debris or micro-organisms, more washes occur if the flush fluid was dirty, suggestive that the donor mare s uterus was not healthy and, therefore, capable of adversely affecting the embryo. The catheter is attached via y tubing to the pre-warmed embryo flush medium and a filter cup, which will catch the embryo.. The recipient mare is prepared for the transfer. First, a rectal examination and ultrasound establish her uterus is quiet and fluid-free, she has a clear CL (corpus luteum) and a tight cervix - all of which indicate that her progesterone level is suitable for pregnancy. Then she is cleaned with a thorough surgical scrub of her perineum, sedated and given drugs which, depending on the practitioner s preference, may include an anti-inflammatory, antibiotics and hormones. Page 14 HORSES and PEOPLE Phone: 07 5467 9796 admin@horsesandpeople.com.au
Between flushes the cup is disconnected and the contents checked for an embryo under microscope. Beware of Tooth Fairies Qualified & Experienced Licensed Regulated Insured Continually updated skills and knowledge Choose wisely Get the facts: www.horsesandpeople.com.au HORSES and PEOPLE Page 15
The embryo is drawn up into a straw in a fluid bubble and the straw is put into a transfer gun, which is in a sterile plastic sleeve. The gun is passed through the vagina to the cervix where the sleeve is pulled back. The gun is manipulated through the cervix into the uterus with as least disturbance to the cervix or uterus as possible. This is the hardest part of the whole procedure. Then the embryo is pushed out of the straw and the gun gently withdrawn. Embryo transfer s success is multi-factorial and includes the recipient mare s reproductive health, the day of ovulation and stress levels, as well as the quality of her management throughout the pregnancy. The recipient mare It is very exciting to retrieve an embryo, but implanting it into a suitable recipient mare is crucial to success. The general preference in Australia and at Illawarra Equine Centre is to use Standardbred mares aged between three and 10 years. We try to choose nice types, good size, calm temperaments and catchable, with perfect uterus and vulva conformation. The mares are very well managed year round. They are all wormed regularly, have their feet and teeth attended to, and are caught and tied up most days as they are scanned routinely every second day to follow their cycle. When a donor mare is close to insemination, the recipient herd is checked to find two mares that will ovulate preferably 1-2 days after the donor mare. These mares cycles are followed to determine the day of ovulation and their uteruses are checked for fluid as there should be none at time of implantation - that s why there are always two mares prepared as a back-up is necessary or the embryo will not survive. Following the transfer of the embryo, the recipient mare is managed as best as possible to minimise stress. She is kept in the same paddock with her buddies and fed the same. This month s contributor to the health feature from Equine Dental Vets Gillian Rickard, BVSc (Hons) BEd (Hons) Gill has been involved with horses since she was seven years old and has bred, ridden and competed them ever since. Gill represented Australia in Dressage on a palomino mare called Peaches and Cream at the first WEG in Stockholm, 1990. Originally a school teacher, then a professional rider and coach, and then, more recently, went back to university to become a veterinarian, so she could combine years of horse experience with science to help keep horses happy, healthy and productive. Her professional interests are reproduction, dentistry and preventative health - especially for pleasure and sport horses - all of which she carries out at Illawarra Equine Centre near Berry, NSW. Gill currently competes an Andalusian stallion Grandioso in dressage and still gives dressage lessons when time allows. For more information, visit www.illawarraequinecentre.com.au. Page 16 HORSES and PEOPLE Phone: 07 5467 9796 admin@horsesandpeople.com.au
Equine Dental Vets Qualified & Experienced Licensed Regulated Insured Continually updated skills and knowledge Above: Image of a seven-day-old embryo flushed at the Illawarra Equine Centre. Pregnancy test Five days after the transfer we perform the first pregnancy test. It is always tremendously satisfying to see that round black circle on the ultrasound screen and to make an equally happy phone call to the client. Further pregnancy tests are performed until 45 days when the recipient mare generally goes home to her new owners. We encourage owners to treat the recipient mare as well as they would their own broodmares - regular worming, dentals, vaccinations, foot care and good handling will all be necessary to ensure a healthy foal is the outcome. Success Whilst ET has progressed in its success rate, the factors affecting success should be considered by every mare owner before embarking on what is an expensive program. The most important factors are: The donor mare s age - younger being better than older - her uterine health, fertility and time of season all play a big part. The stallion s fertility and quality of semen whether it is fresh, chilled or frozen. The recipient mare s reproductive health, the day of ovulation, stress levels and quality of management throughout the pregnancy. The expertise needed for insemination, post-breeding follow-up, flush, transfer and recipient mare management. Weighing up your options There are often easier ways to get a foal, but if your mare factors make embryo transfer the best option and your breeding budget allows it, then my recommendation is to go into it knowing that, while success is not guaranteed, if you follow the advice of an experienced ET veterinarian, you have a better chance to get your dream foal. and Real vets who really care about horses Get the facts: www.horsesandpeople.com.au HORSES and PEOPLE Page 17