Loch Leven Equine Practice

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- The Procedure

Breeding a foal is a wonderful experience but for those of you that have not been involved in this before there are some important things to consider before we get started.

Firstly do you have a suitable mare? While it is not impossible to get older maiden mares in foal, it is well known that success rates are higher in younger mares.
If you are not sure about your mare then we can come out and examine her and her reproductive tract to give you a better idea of your chances. Mares should be in good body condition - not too fat and not too thin, be free of worms and in general be sound and healthy.

All mares should also be tested for Equine Viral Arteritis (EVA ) and Contagious Equine Metritis (CEM) which are pathogens that can cause abortion.

Secondly is there a particular stallion that you would like a foal from, in what form will you be able to obtain semen from him (i.e. natural mating or artificial insemination). How many days noticed do you need to give the owner of the stallion to order the semen?
It is vital to have all of this information prior to beginning the process as perfect timing is essential in breeding and any interruptions may negatively affect our success rate.
Other Basic questions that you may like to ask the stud include - does he have good fertility, are there any dates where he may be competing and therefore not available to get semen, has he been tested for EVA and CEM and what is their policy if the mare does not become pregnant?

Thirdly you need to consider what you will do with your mare once she is pregnant and approaches foaling. Pregnancy lasts for approximately 340 days +/- 3 weeks (11months) and she will need a close eye and good management through this time to make sure everything is running smoothly. It is also best to start thinking about where you will be foaling her down. Will it be at your house or at a professional stud that is experienced with foaling mares? Mares need constant monitoring up to and throughout the birthing process and so a stable with lighting and some knowledge of what to expect is vital.

Once you have considered all of these points, have a stallion lined up and are happy to get started then call the office and arrange a time for us to come and see your mare.



Pre insemination

This first visit should be once your mare has started cycling regularly after her transitional period. Here, in Scotland, this may not be until March or April. At this first visit we will do a thorough ultrasonographic and physical examination to determine what phase of the cycle she is in, and assess her for any abnormalities that may impact on our success.

If the mare is in dioestrus and has no abnormalities that need to be treated then we may give her a prostaglandin injection to shorten the time it takes her to come into oestrus. Once injected we will want to scan her every couple of days to monitor the development of the follicles so that we can accurately predict the time of ovulation and therefore have her inseminated at the right time.

To assist in the precise timing of ovulation we may administer drugs such as ‘Ovuplant’ or ‘Chorulon’. Semen needs several hours in the uterus to capacitate (become fertile) and can last at least 48 hours in the uterus (fresh or chilled semen, frozen semen does not last as long). The oocyte will degenerate within 8-12 hours of ovulation. Therefore insemination should ideally occur within the 48 hours before ovulation. Conception rates fall markedly if animals are inseminated more than six hours post ovulation.

For frozen semen, mares will need to be scanned every six hours for the two days up to the point of ovulation as the frozen semen does not last very long in the mare and therefore the timing needs to be very precise.

Due to this frequent scanning programme mares must be liveried at the clinic is frozen semen is being used.

Post insemination

Following insemination we will scan the mare again to make sure that she has ovulated and to ensure that she has no fluid in her uterus. Temporary inflammation of the uterus following natural service or artificial insemination is a normal phenomenon and normal mares will clear this inflammation from their uterus within 12 hours of insemination.

Unfortunately some mares, more commonly older mares, do not have this ability to clear it and the presence of this inflammatory debris will set off a vicious cycle of fluid accumulation and inflammation. It is not known whether this inability is mechanical or physiological but either way veterinary intervention is required. To treat this we use sterile fluid to lavage the uterus and physically drain the inflammatory fluid away. We also place antibiotics into the uterus itself to help prevent infections and administer Oxytocin which causes the uterus to contract and push the fluid out. Thankfully in mares fertilisation of the egg occurs in the oviduct and not in the body of the uterus. The embryo stays in the oviduct for 4-5 days giving us plenty of time to correct the inflammation in the uterus before the embryo arrives.

It is due to this inflammatory reaction that, counter-intuitively, conception rates are highest when there is only one insemination per cycle. Repeat mating’s increase the likelihood of the embryo entering an infected uterine environment. This point highlights the importance of the vets role in accurately predicting the time of ovulation. Also, semen from any given stallion is limited in quantity, so stallion owners are much happier when they only need to give one dose per cycle.

Pregnancy diagnosis

The first pregnancy scan will be 14-16 days after the day she ovulated. This timing allows the detection of pregnancy and easy management of twins if they are present. If the mare is not pregnant this timing also allows us to catch the next cycle in time as she will be due to enter the oestrus phase in the next couple of days.

The next scans will be at 25-30 days. At this time a heart beat will be present in the foetus if it is developing normally. At around day 35 of pregnancy the endometrial cups on the uterine lining begin to produce a hormone called PMSG whose function is to help maintain pregnancy. After this has taken place the mare is less likely to lose the embryo.

A final scan is then performed after this higher risk time at around 45 days. This is the ‘industry standard’ day for payment of service fees, which are usually on a no foal – no fee or free return basis but will vary from stud to stud.


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Loch Leven Equine Practice
South Kilduff Farm
Kinross KY13 0PN
Tel: 01577 840022