For many of us, the thought of having our very own foal from our own mare is a recurring dream – but what does it take for that to become reality? And is it something we should be considering, for both our mare’s sake and our own?


Breeding a foal can be risky – normally, everything goes to plan, and the foal arrives safely and healthily, and mother is also well and suffers no ill effects from this. However, when it goes wrong, it can really go wrong, and in the worst-case scenario we may lose both mare and foal. Thankfully, this is rare, but it is a risk that should be seriously considered before deciding to breed.

Other considerations should include:

    • Is the mare a good candidate to be bred from? Look objectively at her conformation and temperament. Often mares are put into foal due to lameness or other ridden issues, but if these are due to physical abnormalities then these may be passed on to their offspring.
    • What am I looking to breed? This will influence your choice of stallion, and whether you breed at all.
    • Am I in a position to have a mare and foal, both in terms of finances, and practicalities (e.g. yard set up, other youngstock etc.)?

Choosing a stallion
This is one of the fun parts! Try to choose a stallion that will complement your mare’s conformation and type. Looking at a stallion’s offspring already on the ground may give an idea of temperament.

Bear in mind health testing for certain genetic conditions – this is especially important in certain breeds. If you have any specific questions regarding these please ask one of our vets.


Natural cover is just that – natural! This limits the choice of stallions logistically to those within a travelable distance for the mare. Many competing stallions, for example, may not offer natural cover due to the increased injury risk and the potential for it to affect their focus when competing. Some studs will cover in hand once the mare is in season, and others will allow the stallion to run with the mare for a period of time (the latter is more common in native pony types).

Fresh/chilled artificial insemination – this is where semen is collected from the stallion, and then placed either straight into the mare’s uterus (fresh) or mixed with ‘extender’ (think a little packed lunchbox of nutrients to keep the semen alive in transit) and then posted out to your mare. Chilled semen opens the options for stallions to be used from across the whole of the UK and even most of Europe. Typically chilled semen has a lifespan of around 48 hours from collection (although this will vary from stallion to stallion), so we need to time things carefully to ensure it arrives in time for the mare to be inseminated with it before she ovulates, but not so far in advance that the semen has died!

Frozen AI – this is the most tricky and time consuming, as once frozen semen has thawed it has a much shorter lifespan, and so we scan the mares ovaries much more frequently – normally every 6 hours – and then as soon as she has ovulated the semen is thawed and inseminated via a different type of AI catheter that allows the semen to be placed as close to the ovulating ovary as possible. As this technique requires much more scanning, and the access to a temperature-controlled water bath, liquid nitrogen tank etc., this is typically performed in the clinic rather than on yard. The plus points of frozen AI over chilled include an increased choice of stallions – including those who are deceased – and a lack of restriction on postage, for example over weekends/bank holidays/postal strikes (nightmare!).


Embryo transfer is becoming more established within the UK and involves flushing an embryo from one mare and implanting it into a recipient mare. This is a useful technique for mares who are currently competing or cannot carry a foal themselves for health reasons. This is not something we currently offer at Oakhill (yet), but we can advise you on those who can help if this is something you are considering.

A newer emerging technique is one called ‘ovum pick-up’ where eggs are collected directly from the mare’s ovary, and ‘intra-cytoplasmic sperm injection’, where these eggs are injected with sperm. Once these develop into embryos they can be frozen, stored, and then placed into recipient mares when required. This technique is still in its infancy in this country but is likely to become more common in years to come.


If you choose to breed your mare by AI, then she will typically be scanned to assess where she is at within the oestrous cycle, and to check for any abnormalities that may reduce her ability to conceive and carry a foal. If she is not in season, then she may receive an injection to help bring her into season.

On subsequent scans, the size of any follicles on her ovaries will be measured, and her uterus assessed for oedema. Once we are happy there is a large enough follicle that looks like it will ovulate shortly, along with sufficient uterine oedema, then the semen can be ordered. In some cases, drugs to induce ovulation may be given.

As soon as the semen arrives, it is placed into the mare’s uterus, and the following day she may be scanned to check she has ovulated (if she hasn’t, it might be that more semen needs ordering!), and to check for fluid within the uterus, which can result due to the mare having an inflammatory reaction to semen/extender. If this happens, she may be ‘washed out’ with fluid, and/or antibiotics, to remove any dead semen and inflammatory fluid – but don’t worry, any swimmers that are winners will have reached the oviducts leading to the ovaries by this point and will be safe from us washing them out.

Then comes the long wait for pregnancy scanning – we typically recommend this to be performed 15/16 days after ovulation, as this enables us to check for twins. Unfortunately, twin pregnancies are very risky for mares, and so if there are two embryos, scanning at this point enables us to reduce one embryo, leaving hopefully just the one embryo. If she is in foal at this point, then we check again at 28-35 days to check that the foal is developing normally and by this point its heartbeat should be visible! Further scanning can be performed if there are any concerns after this stage.

It is important to remember that not all mares will become pregnant first time, just the same as with people, and sometimes it can take multiple attempts and further interventions and treatments may be necessary.

If you would like to discuss breeding your mare, please give us a call and ask to speak to Rob, Pete or Sarah