In the last 20 years there have been massive advances in the use of assisted reproductive technologies in horses.

Some of these have quickly become established practice but there are also many new technologies on the horizon that may become commonplace in future.

Assisted reproduction in horses is not new, artificial insemination (AI) was probably first carried out in horses over 2000 years ago and I believe the first documented attempt at chilling equine semen was in1776! However the horse breeding world has been pretty slow to adopt these techniques and it is really only over the last 20 or 30 years that we have seen an explosion in their use.

This coincided with the development of ultrasound for the monitoring of the mare's oestrus cycle and the development of techniques to control and reliably predict ovulation in the mare. Prior to that, even on Thoroughbred studs, ovulation could only be predicted by teasing the mare and making a manual assessment of when the mare was about to ovulate. Even with experienced operators, accuracy was limited and in part explains why previously stallions could only cover about 40-50 mares a season and now many Thoroughbred stallions cover well over 100 mares each year all by natural covering.

Ultrasound is probably the single biggest contributor to the development of new techniques, none of which would be possible without the ability to monitor accurately the mares reproductive cycle.

Once a successful pregnancy has been established hopefully the mare will carry the foetus successfully to term. Again thanks to ultrasound it is possible to monitor mares in late pregnancy looking for problems in the placenta.

Modern ultrasounds allow accurate assessment and measurement of combined utero-placental thickness. The thickness is compared to a series of normal values allowing problems such as placentitis to be identified and treated, enabling many affected mares to carry a healthy foal to term rather than giving birth to a premature and often weak or non-viable foal.

AI allows many more mares to be mated to a single stallion, the mare can be thousands of miles away and by using frozen semen even deceased stallions are still successful sires! Stallion semen is very susceptible to damage during freezing and thawing compared to other domestic species and the semen has to be mixed with what's called a cryoprotectant before freezing. A whole range of new cryoprotectants are now being developed without glycerol; this coupled with new techniques for centrifuging and separating out semen fractions allows a far greater percentage of stallions to have semen successfully frozen.

Having identified when the mare is going to ovulate, inseminated her with good quality semen and then treated any uterine problems we hopefully get successful fertilisation of the egg and development of an embryo. This all occurs in the oviduct and the embryo passes into the uterus at about six days of gestation.

Normally it would go on to develop from here but in the last 20 years improved embryo transfer techniques have been developed allowing the embryo to be non-surgically removed from one 'donor' mare and placed into a suitably synchronised recipient mare. This allows the donor mare to still go back to competing or breed several foals in a year with minimal risk to herself.

We have inseminated one mare three times in the last two seasons using three different stallions. From the three inseminations we recovered five embryos and achieved five pregnancies. The first three foals were born last spring and two more are due any day now. Had we not used embryo transfer the mare could have only produced a maximum of two foals and her owner could not have continued to ride her favourite horse!

Methods have now been developed to cool and transport embryos in a similar method to semen and then ship the embryo for up to 24 hours before transfer into a suitable recipient. You still need a skilled operator to flush the mare and prepare the embryo for shipping but pregnancy rates above 80% are now regularly achieved with embryos shipped for up to 24 hours. Embryo transfer opens up a whole new range of fertility treatments that are all really in the development stage at the moment.

Oocyte transfer harvests eggs rather than embryos from the donor mare and then transplants the unfertilised egg into another mare. In the majority of cases the donor mare is prepared as for a normal mating but immediately prior to ovulation the eggs are harvested and transferred into a recipient mare whose own oocytes have been removed. Pregnancies have even been obtained by the emergency harvesting of eggs from the ovaries of mares that have died or been euthanased.

Another relatively new procedure is the harvesting of semen as an emergency procedure from recently deceased or castrated stallions. Mature spermatozoa are stored in the epididymus and these can be successfully flushed and frozen. Although visually the semen does not look as viable as that from natural collections, fertile semen can be recovered and frozen.

Liverpool University are currently doing a study into ICSI (intracytoplasmic sperm injection). With ICSI mature eggs are harvested from the mare and then after preparation in the laboratory an individual sperm is beheaded and the head injected straight into the egg using micro manipulation techniques. At this stage Liverpool are producing and growing embryos in the laboratory and hope to achieve pregnancies by non surgical transfer this year.

The most futuristic technique is probably cloning. Since the birth of Dolly the sheep many animal species have been successfully cloned. The biggest company looking at cloning in horses is Viagen in the US. If you have $155,000 burning a hole in your pocket they will happily offer to clone your favourite horse for you! Whilst this may sound ridiculous they have already produced over 50 cloned foals and some of these are stallions produced from geldings intended for breeding in the future.

Breeding horses has always been about creating the horse of your dreams. Whilst many of these techniques may seem far fetched they are all being used by someone somewhere in the world attempting to breed their dream horse right now!