01622 813700 SignVideo

Reproductive Medicine

We have been running an artificial insemination service here for more than 16 years. Over this time we have identified there are many key factors that require careful consideration before breeding from your mare. More information is available on this website regarding all aspects of equine breeding.

We recommend that all potential AI mares should have a detailed 'pre-breeding check'. We offer a 'Pre-Breeding Package' which includes:

  • a thorough gynaecological assessment
  • ultrasonography of the reproductive tract
  • a blood test for equine viral arteritis (EVA)
  • a clitoral swab for contagious equine metritis (CEM).

The cost of this pre-breeding package is £165 (incl VAT) . This includes laboratory fees but does not include any call out fee which is dependent on area. All mares and stallions involved in our AI programme will need to be confirmed free of venereal infection (CEM and EVA) by routine bloods and swabs taken after 1st January 2021, before being accepted for breeding purposes.

AI package fees include the cost of routine veterinary examinations and ultrasound scans during the mare's oestrus period; a 14-16 day pregnancy scan and 28-30 day heart beat scan (which must be performed at the clinic).  Any procedures that are not considered routine would be discussed with the owner. Please be aware these procedures would incur extra cost, such as treatment for a uterine infection.

We prefer and strongly recommend for mares to be kept at the hospital for their oestrus period. This enables us to monitor the mare closely with frequent examinations if necessary, in addition to providing a safe and clean location for the procedures to be performed.  AI with chilled semen can be performed at home depending on the nature of the mare and facilities available.  Please call BELL to discuss the costs for the package in this situation.  With frozen semen, due to the nature of the semen storage and handling, the mare MUST be brought to the clinic during her oestrus cycle.

AI CHILLED SEMEN PACKAGE                    £395 (incl VAT)

  • Grass livery (5 days included)
  • Endometrial swab and smear (to check for endometritis)
  • All routine gynaecological examinations, including ultrasound examinations
  • Induction of ovulation
  • Routine breeding medications - Oxytocin / Deslorelin / Estrumate (as required)
  • Semen ordering and handling (not including shipping fees)
  • Semen evaluation and insemination
  • Post ovulation check
  • One uterine lavage post insemination (if required)
  • 14-16 day pregnancy scan at Bell Equine
  • 28-30 day heart beat scan at Bell Equine

AI FROZEN SEMEN PACKAGE                    £495 (incl VAT)

  • Grass livery (5 days included) & 1 night stabling
  • Endometrial swab and smear (to check for endometritis)
  • All routine gynaecological examinations, including ultrasound examinations
  • Induction of ovulation
  • Routine breeding medications - Oxytocin / Deslorelin / Estrumate (as required)
  • Semen ordering and handling (does not include shipping fees)
  • Preparation, handling and thawing of frozen semen
  • Semen evaluation and insemination
  • Post ovulation check
  • One uterine lavage post ovulation (if required)
  • 14-16 day pregnancy scan at Bell Equine 
  • 28-30 day heart beat scan at Bell Equine


If your mare does not conceive on the first cycle, the second cycle is available at the below reduced costs:

  • repeat chilled semen package -  £335 (incl VAT)
  • repeat frozen semen package - £435 (incl VAT)


  • Any visit fees for work performed away from the clinic
  • Pre-insemination health tests (EVA, CEM - see above for the 'Pre-breeding Package')
  • Semen importation / shipping fees and the potential cost of returning any unused semen at the end of the season
  • Treatment for endometritis - this could add up to £100+ to the final bill, depending on treatment required
  • Repeated uterine lavage
  • Caslicks's procedure
  • Sedation
  • Twinning
  • Extra nights of boarding (more than 5 days) or stabling rather than grass livery

N.B. For both frozen and chilled inseminations, mares which are at higher risk of twins are recommended to have TWO scans between 14-18 days.

‚ÄčAll stallion semen must have full original paperwork confirming it is disease free before it will be accepted at the hospital. Mares cannot be inseminated until this paperwork is available and in order.


Frozen semen can be stored here at the clinic whilst the mare is undergo AI or during the course of the season (1st April - 1st September). However, once the mare is confirmed 60 days in foal, charges of £25 (incl VAT) per month will be made for any remaining doses of semen.

Clients are required to make other storage arrangements by 1st September as any other semen remaining in storage at the hospital will be charged at this rate.

Frozen semen stored at the clinic is done so at the mare owner's own risk, who is also responsible for the insurance of the semen.

Payment terms:

Our full terms and conditions of business can be found here.

Our terms require for all in-patients admited to the hospital, a hospital deposit or to provide credit card details on arrival to confirm intent to pay for treatment. 


If you have any questions relating to our AI services, or regarding any aspect of equine breeding, please do not hesitate to contact any of the team at BELL EQUINE who are involved in our equine breeding programme on 01622 813700.

There are several important factors that anyone contemplating breeding should consider:

  • Is your mare suitable for breeding? Traits such as conformation and temperament are highly heritable and should be important considerations when selecting a mare. Mares with serious conformational faults or temperament issues are not ideal candidates. Mares considered suitable would have shown a high quality of performance during their competing career and have an amenable and reliable temperament.

  • Is your mare in good health? Health, body condition, vaccination and worming status can play an important role in the fertility of your mare.

  • How old is your mare? Mares should ideally be bred before 12 years of age. After this, fertility rates reduce significantly and there may be more problems with your mare maintaining the pregnancy and foaling.
  • Has the mare bred before? If yes, have you seen previous foals of the mare? Did she foal with any problems? These questions should be asked if buying a broodmare with the intention of further breeding.
  • Where do I foal the mare? Consideration must also be given to the facilities required. You will need a large foaling box, ideally with foaling cameras available, a 'nursery' field that is suitably fenced and good quality pasture.  Turnout with a similarly aged mare and foal is recommended.
  • Can I afford it? Stud fees and AI charges, in addition to livery, routine and unexpected veterinary bills can add up to a substantial sum and there is no guarantee that a healthy foal will be produced or if that foal will mature into a quality horse. So careful thought is required from the outset.

Mare Reproductive Cycle - General Information

Most mares have a 21 day oestrous cycle. This is divided into:

  • Oestrus (average 5 - 7 days)
  • Dioestrus (14 - 16 days).

The cycles begin at puberty (approximately 18 - 24 months) and continue throughout the mare’s life.

The mare is receptive to the stallion and is said to be ‘in season’. Typical signs of oestrus include:

  • Adopting a urinating stance with the tail raised and passing small squirts of urine
  • Opening and closing the vulval lips. This is known as ‘winking’

During this time one or more follicles within the ovaries increase in size and rupture to release an egg (ovulation). The mare normally ovulates approximately 24 hours before the end of oestrus. The exact timing of ovulation can only be determined by performing repeated ultrasound scans of the ovaries. The maturation of the follicle can be monitored by the vet by successive rectal ultrasound examinations.

The mare is no longer receptive and may behave aggressively towards the stallion. She is likely to put her ears back, swish her tail and may squeal or lash out.

Control of the oestrous cycle:

Mares have a seasonal breeding period which is influenced by factors such as daylight length, temperature and nutrition. 

Environmental and other effects (e.g. nutrition, lameness, worming etc) can exert a significant effect on the mares' reproductive cycle, especially during the ‘transitional period’. The transitional period is the period between winter anoestrous (when the mare does not cycle) and the onset of cyclic activity in the spring. The transition period also occurs in autumn when mares cease cycling and return to winter anoestrous. There are exceptions to this rule, as some mares (up to 30%) will cycle all year round.

The production of hormones that trigger the mare to start cycling is controlled by daylight. Therefore, the natural breeding season in the mare is strongest from May until August, when the days are longest and the weather is warmest.

During the spring months i.e. Feb-April the weather can be very variable and daylight hours are still relatively short. This in turn creates very variable oestrous activity in the mare, with one or more of the following scenarios often occurring:

  • No oestrous behaviour seen
  • Erratic and often confusing signs of oestrus behaviour
  • Oestrous behaviour seen, but no dominant follicle growing and hence no ovulation
  • Long or unpredictable length of cycle

During this period it is often difficult to predict when the mare will ovulate and thus determine the precise time to cover a mare. Because it is not cost effective to use stallions or stored semen during this unpredictable period, it is often wise to artificially manipulate the mare to encourage normal cycling and shorten the transitional period as much as possible. This can be done in a number of ways:

  • Artificially increasing daylight - Studied have shown that increasing daylight to 14-16 hours (natural plus artificial) daily for a minimum of 8-10 weeks can induce normal cycling.
  • Progestogens - progesterone treatment suppresses the release of luteinising hormone (LH) during administration. This allows LH to build up which is stored. When progesterone treatment is stopped, a huge surge in LH induces a strong oestrous which usually results in ovulation. ReguMate® (Altrenogest) given orally once daily for 10-15 days is commonly used during the transitional period. Mares come into season 4-7 days and ovulation occurs 7-12 days after treatment has stopped. We also use progesterone releasing devices which we place in the vagina for 10-12 days. These drugs are shown to encourage ovulation and result in more successful insemination.

Gestation Length

The gestation (pregnancy) length is 11 months (340 days) but considerable variation occurs with a range of 320 – 360 days, and sometimes even longer.

The choice of stallion should be made after consideration of the following factors:

  • Conformation, temperament and size
  • Soundness and freedom from hereditary conditions (observation of their offspring is very useful)
  • Performance records during his working career
  • Temperament (ideally calm and kind)
  • Fertility record - this should be available from the stud manager, however precise fertility results are often unknown
  • Type of semen available - fresh, frozen or chilled? This can have a direct impact on the management, costs and success of a breeding your mare
  • Cost and terms of the stud fee
  • Availability of semen - some stallions are competing through the spring / summer and therefore unavailable for semen collection at certain times

Health status:

  • Due to our increasing concern of the spread of infectious diseases, we can ONLY accept semen from a stallion for AI which has been tested for CEM, EVA & EIA after the 1st January. We therefore request this certification arrives with the semen at the clinic, otherwise we will be unable to proceed with insemination.  This is already mandatory for all EU / foreign stallions, and we will also be requesting this for UK stallions.

The Horserace Betting Levy Board (HBLB) publishes 'codes of practice' for pre-breeding tests annually.

The risk of infectious diseases, including venereal and exotic diseases, has never been higher for the UK horse population, making it extremely important to perform routine pre-breeding tests. 

Different studs / AI centres / veterinary clinics will specify which tests they require before breeding, so it is important to contact them well in advance of breeding to discuss the tests they will require and when they need to be carried out.

Requirements for mares coming into Bell Equine Veterinary Clinic for AI

  • A clitoral swab for CEM, Klebsiella pneumoniae and Psedomonas aeroginosa
  • Blood sample for EVA
  • Up to date influenza and tetanus vaccinations are recommended.


Any of the following possible requirements could be requested if using studs or other AI facilities:


  • Equine influenza and tetanus. All horses should be up to date with influenza and tetanus vaccinations. You may be asked to produce an up to date copy of your vaccinations with your passport.
  • Clitoral swabs are taken for CEM, Klebsiella pneumoniae and Pseudomonas aeroginosa after January 1st of the current year. This is carried out by the vet and can be performed at any stage of the reproductive cycle. Swabs sent for culture will required a week for the results to return, however, PCR testing is now available with results returned within 48 hours (although this is more expensive than culture).  A CEM certificate will be produced and should accompany the mare to the stud / AI centre.
  • Endometrial swab for bacterial infection. This is taken by passing a guarded swab through the mare’s cervix into the uterus. This must be performed when the mare is in oestus and the cervix is relaxed and open. The swab usually takes 24-48hrs to process. A second swab is also used to collect cytology from the mare's uterus. The slide is examined for the presence of increased numbers of neutrophils which is indicative of inflammation of the endometrium known as endometritis. These swabs can be performed in the preceding oestrus cycle before breeding or at the beginning of oestrus so that the mare can be covered in the same oestrus if the results are satisfactory. Most studs prefer to perform the swab on their own premises once the mare has arrived, but an increasing number of studs are requesting this before admission of the mare. It is therefore very important to check with the stud / AI centre or veterinary clinic first.
  • Blood sample for Equine Viral Arteritis Virus (EVA) after January 1st of the current year with a negative result. This test takes 24-48 hrs to process once it has reached the lab. This result should also accompany the mare to the stud.
  • Blood test for Equine Infectious Anaemia (EIA) – a “Coggins Test”. EIA is a notifiable disease and had not been seen in the UK since 1976. However, two confirmed cases in the UK early in 2010, has resulted in extra vigilance for this virus. Some studs may request this test to be performed before accepting a mare for breeding. 
  • A recent addition to testing is a negative blood test result for “Strangles” (Strep equi). This needs to be taken within 28 days of the mare going to stud / AI centres. If the blood test returns borderline / positive, please contact BELL EQUINE for further advice. 


  • Equine influenza virus and tetanus. All horses should be up to date with influenza and tetanus vaccinations. You may be asked to produce an up to date copy of your vaccinations with your passport.
  • A certificate for Contagious Equine Metritis (CEM) testing in the current breeding season according to HBLB protocols is required. Two sets of swabs taken at least 7 days apart; swabs are taken from the urethra, urethral fossa, penile sheath and pre-ejaculatory fluid where possible.
  • A negative blood tests for EVA and EIA.
  • Swab or blood sample for Strep Equi (strangles).

The vet is usually consulted at several stages of the breeding programme, for example:

  • gynaecological examinations during oestrus
  • pregnancy diagnosis and regular checks throughout gestation
  • pre-foaling vaccination
  • post-foaling checks


Pre-breeding checks:

The purpose of the examination is to assess any problems that could affect the mare’s ability to conceive or carry the foal to full term. Ideally the checks should be made early in the season so any problems can be detected and treated.


The vet will requested the following information:

  • name
  • age
  • breed
  • previous breeding history
  • previous foaling history
  • health problems such as lameness, colic, cushings
  • vaccination and worming status
  • body condition

Gynaecological examination:

This includes:

  • visual inspection and assessment of the vulva, vagina and cervix
  • rectal palpation and ultrasonographic examination of the uterus and ovaries. Ultrasonographic examinations can reveal the presence of abnormal amounts of fluid within the uterus and endometrial cysts, which can be mistaken for an embryo if not identified pre-breeding
  • collecting swabs for CEM culture / PCR from the clitorus 
  • performing an endometrial swab for culture and cytology 


If purpose-built stocks are not available the mare should be examined in a stable. She must be adequately restrained by a competent handler and it is helpful if her tail is bandaged. The vet will require:

  • a bucket of clean, warm water
  • an assistant to hold the tail out of the way
  • a power supply for the scanner

Sometimes it is necessary to apply a twitch or sedate the mare for the examination.

Assessment of the vulva:

The vulva is checked for any signs of discharge. The vulval lips should be almost vertical and meet together in the midline, forming a firm seal. If the vulva slopes forwards, the seal is easily broken and air may be sucked into the vagina as the mare moves. Aspiration of air and contamination by faeces can lead to inflammation of the vagina, cervix and the lining of the uterus with resultant infertility.

If the vulval conformation is poor, a Caslick’s operation may be carried out. This involves suturing the upper part of the vulval lips together under local anaesthetic. This must then be opened before the mare foals or she will tear during foaling. Ideally this should be done by the vet 1 - 2 weeks prior to foaling.

Treatment of endometritis:

When labatory results show a mare is suffering from endometritis, she is likely to be treated with infusions of sterile saline and antibiotics into the uterus for a period of 3 - 5 days. A mare with endometritis will have reduced conception rates or may suffer from early embryonic loss, so it is important to identify and treat these mares before covering.

A second swab and smear must be taken early in the following oestrus. If the treatment has been successful and there is no evidence of endometritis, the mare can be covered / inseminated.

Endometrial biopsy:

If the mare fails to conceive, or the swabs and smears reveal persistent or recurrent infection or inflammation, an endometrial biopsy may be taken. This can be done at any stage of the cycle but is easiest during oestrus.

Biopsy forceps are passed through the cervix and a small piece of endometrium is removed and sent to a laboratory for histology (examination of the tissue under the microscope). This reveals the extent of any inflammatory or degenerative changes in the endometrium. Treatment can then be recommended and a prognosis for successful breeding given. A second biopsy is taken approximately one month later to assess the results of treatment.

Endometrial endoscopy:

Examination of the endometrium with an endoscope can provide the vet with valuable information such as the presence of cysts and damage sustained during previous pregnancies. The normal endometrium is smooth and pink in appearance. An inflamed endometrium may appear very haemorrhagic and have adhesions which obstruct the passage of the endoscope. Occasionally foreign bodies can be found using this procedure.

Contagious Equine Metritis (CEM):

CEM caused by Tayorella equigenitalis is a notifiable disease in the UK. Any occurrence must be reported to the Divisional Veterinary Manager of DEFRA.

Clinical signs:

Most stallions carrying the disease show no outward signs. Mares may have a grey, mucoid vulval discharge or they can also be symptomless carriers of the disease.


The disease is transmitted:

  • during mating, including artificial insemination
  • during teasing,
  • by poor hygiene standards when handling mare


Diagnosis is confirmed by culture or PCR when a swab is taken from :

The Mare:

  • the clitoris - the fossa and sinuses
  • a specific endometrial swab during oestrus (NB some stallions studs request this as routine)

The Stallion:

  • from the urethra, urethral fossa, penile sheath and pre-ejaculatory fluid if possible.

The swabs must be sent to an approved laboratory.


Stallions are treated by thorough cleaning of the penis with an approved antiseptic solution and application of an antibiotic ointment for 5-7 days following removal of all accumulated smegma. 

Stallions require three sets of negative swabs taken at intervals of at least seven days before they can be confirmed free of infection. In addition, the first three mares mated or inseminated by the stallion should have clitoral swabs taken three times at intervals of at least seven days, starting two days after mating or insemination. These must be negative.

Mares are treated with intrauterine infusions of antibiotics in addition to thorough cleaning of the clitoral region and topical antibiotic treatment. With stubborn infections that are difficult to clear, surgical removal of the clitoris may be performed. 

Freedom from infection in mares is confirmed by three negative clitoral swabs taken at intervals of at least seven days and three negative endometrial swabs taken during successive oestrous periods.


If a case is confirmed, there is a Code of Practice published by the Horserace Betting Levy Board (HBLB) that must be strictly adhered to. This includes:

  • Stopping all breeding activity immediately
  • Isolation and swabbing of infected horses
  • Swabbing of at risk contacts
  • Notification of the relevant breeders association
  • Notification of owners of mares who have left the premises, are booked to the stallion or have been inseminated with semen
  • Testing of stored semen
  • Foaling of pregnant mares that have been exposed to the infection in isolation. The placenta must be burned and both filly and colt foals swabbed

Breeding should not be resumed until the premises are confirmed as free from the disease.


The disease can be prevented by strict adherence to the recommendations for swabbing in the HBLB Code of Practice. The swabs should be taken from mares and stallions after 1st January of the year in which breeding activity is planned. Additional swabs are taken from stallions in the middle of the breeding season.

Equine Viral Arteritis (EVA):

EVA is also a notifiable disease in the UK. The highly contagious virus is common worldwide including mainland Europe.


  • Aerosol spread - direct contact with droplets from the respiratory tract e.g. coughing or snorting
  • Infected semen - during natural covering and Artificial Insemination
  • Contact with aborted fetus and placenta of infected mares

Clinical signs:

  • Fever, depression, lethargy
  • Stiff movement
  • Nasal discharge
  • Conjunctivitis ('pink eye')
  • Swelling around the eye, lower legs and reproductive tract
  • Abortions


  • Serology - blood samples to look for antibodies to the virus
  • Virus detection tests - nasopharyngeal swab, urine, semen and aborted material. In the case of abortion, the foetus and placenta are sent to the lab


There is no effective treatment for EVA.


Establish freedom of infection before breeding - routine blood test taken at pre-breeding exam.

Equine Infection Anaemia (EIA):

EIA is sometimes referred to as 'swamp fever' and is notifiable. It is common worldwide, including Europe. There were two confirmed cases in January 2010 in Wiltshire UK after importation from Romania and Belgium.


  • Insect vectors such as biting flies (horse flies and stable flies)
  • Bodily fluids - saliva, nasal secretions, faeces, semen, blood and milk
  • Contamination of equipment with blood or other bodily secretions
  • From mare to foal via the placenta, or colostrum or milk in new-born foals

Clinical signs:

  • Recurring fever
  • Anaemia
  • Oedema
  • Emaciation
  • Death


Infected horses are euthanised on welfare grounds and also to protect the rest of the horse population from infection under government notifiable disease regulations.


No vaccine is available therefore control is based on establishment of freedom of infection. Serology is performed on blood samples taken at pre-breeding exams.

Equine Herpesvirus (EHV):

EHV is a common virus that affects horse populations worldwide. Two forms of the disease exist; EHV-1, which causes respiratory disease, abortions and paralysis; and EHV-4, which usually causes respiratory disease only but can cause abortions.


  • Aerosol droplets from the respiratory tract e.g. coughing and snorting
  • Contact with aborted foetus, foetal fluids and membranes
  • Foals born from infected mares are highly contagious and shed the virus in the environment
  • Indirect transmission from the environment as the virus can survive for several weeks
  • Horses commonly act as carriers and shed the infection without showing any clinical signs

Clinical signs:

  • Develop 2 weeks to months after infection
  • Mild fever, coughing and nasal discharge
  • Foals that are infected in the uterus from the mare are usually born with weakness, jaundice, difficulty breathing and neurological signs. They usually die within 3 weeks
  • Abortions
  • Paralysis - incoordination of the hind limbs, urinary incontinence and in severe cases lying down and unable to stand (recumbancy)


  • Virus isolation is performed on nasopharyngeal swabs and blood samples
  • Aborted foetus - detailed samples are collected by the vet from the aborted foetus and placenta


No specific treatment for EHV. Rest, intensive care and nursing are necessary to minimize secondary bacterial infections.


Management practices that reduce viral spread:

  • New horses should be isolated for 3-4 weeks before mixing with resident horses
  • Pregnant mares should be kept together in small fixed groups according to their stage of gestation. No mixing of pregnant mares with weanlings, yearlings or any horses in training that are high risk carriers
  • Stressing mares in late pregnancy should be avoided, to minimize the activation of latent carriers
  • Isolate affected horses and seek veterinary advice

Vaccinations are available and widely used in the UK. Non-pregnant horses can be given a primary course of 2 injections 4 - 6 weeks apart with boosters every 6 months. Pregnant mares are vaccinated with an EHV vaccine at 5, 7 and 9th month of gestation.

Pregnancy diagnosis in the mare:

There are a number of procedures used to confirm that a mare is in foal. It is best to talk to your vet to decide which would be the most accurate and safe for your mare.

Ultrasound Scanning:

This is the most commonly used method for pregnancy diagnosis and the assessment of early foetal growth. The first scan is performed on day 14 -15 after ovulation (16 - 17 post covering).

It is the most reliable method of detecting twin pregnancies. Two scans are required between 14 - 18 days following ovulation if the mare has double ovulated. The most successful time to remove a twin is during this time. Twins identified after this stage are unlikely to survive.

A heart beat scan is then recommended at 28 - 30 days following ovulation. We can also check there is no twin that has developed during this time.

A final scan is then recommended between 45 - 60 days. At 60 days it may be possible to perform foetal sexing if you wish to know the gender of the foal.

Rectal palpation:

If ultrasound is unavailable or the mare is mid-pregnancy, a rectal palpation can be performed. The vet assesses the tone, size and position of the uterus which changes as the pregnancy advances. The foal may be felt from around mid-pregnancy. The vet may inspect the cervix which is usually whiter and much more tightly closed that the cervix of a non-pregnant mare. The rectal findings during early pregnancy are not always conclusive and cannot eliminate the possibility of twin conceptuses.

Blood tests:

Equine chorionic gonadotrophin (eCG)-
From days 45-90, a blood sample may be taken and tested for the presence of eCG. This is produced by structures called endometrial cups which form when foetal cells invade the endometrium. The test is approximately 90% accurate. Occasionally a mare produces a false negative result, but inaccuracies more commonly involve false positives. This is because eCG continues to be produced if the foetus dies.

Oestrone sulphate-
Oestrone sulphate is produced by the foetus and can be detected in the serum of pregnant mares from day 120. The levels fall in the last few weeks of pregnancy.

Urine tests-
Oestrogens produced by the placenta and the foetus are present in the mare’s urine from 150 days to full term, but the current testing kits available are not always deemed reliable.

Once the pregnant mare is back at home, she will still require:

  • routine daily inspection
  • checking of her teats and perineum (to check for vulval discharge)
  • annual vaccination against influenza and tetanus
  • regular farriery - every 6 - 8 weeks
  • dental care- every 6 -12 months


Worm throughout pregnancy as usual, but it it important to check the wormer is licenced for broodmares. We would also recommend worming during the foaling period, either in the week before or after. Wormers that are safe to use are: Equest, Eqvalan, Strongid P, Panacur,  Panacur guard and Equimax. Please see our advice for worming broodmares and youngstock here, or call the clinic on 01622 813700 and speak to any of our vets for guidance.


  • Influenza and tetanus booster 3-6 weeks before foaling gives the foal maximum protection until 4-6 months of age
  • Equine Herpes Virus (EHV1-4) vaccinations are given in the 5th, 7th and 9th months of gestation. This is highly recommended for broodmares at large studs
  • Rotavirus vaccinations can protect foals from diarrhoea. These are optional vaccinations that are given in the 8th, 9th and 10th months of pregnancy - this is also recommended for broodmares foaling at large studs


The most important part of pregnancy from a nutritional point of view is the last 3 months when the foal is growing most rapidly. During this time the foal will gain 60-65% of his total birth weight.
At 9 months of pregnancy the mare’s energy demands increase by 10%.
At 11 months of pregnancy the mare’s energy demands increase by 20%.
As the foal increases in size, the mare’s appetite will reduce as it takes up more room in her abdomen. This is when concentrates need to be increased to make up the increasing energy requirements and reduced appetite. Energy is also required for colostrum and milk production. If the mare is not fed to meet these demands, she will draw energy from her body reserves which will lead to her losing condition and reducing her fertility for future breeding.
General feeding rules to follow are:

  • Pregnant mares should be maintained at a moderate body condition of (condition score 2.5 - 3)
  • Overweight mares should be put on a weight reduction programme during the first 90 days to reduce the risk of early embryonic death
  • Ad lib forage at all times during pregnancy
  • First 8 months of pregnancy - mares can maintain themselves on good pasture and good quality hay. Minimal supplementary feed needed. If pasture is particularly poor then a broodmare ration can be fed
  • Last 3 months supplement with a stud mix. This has increased energy and protein content, and is supplemented with vitamins and minerals. This can also be fed throughout lactation.



This depends on many factors such as the size, age, condition and fitness of the mare and the weight of the rider. Strenuous exercise should be discontinued from the 6th month of gestation. The brood mare should be turned out each day.

Pregnancy failure can be divided into two categories:

  1. Early Embryonic Loss
  2. Abortions


Death of the conceptus 15-50 days after ovulation has been estimated to be 5-24%.

Maternal factors:

  • Endocrine - low progesterone production. This can be due to failure of maternal-foetal recognition or deficiencies in ovarian progesterone production
  • Oviduct environment - improper timing of insemination so the ovulated egg and sperm do not meet at the correct place.
  • Uterine environment - endometritis, fibrosis, intraluminal fluid accumulation, large endometrial cysts. Any problem with the previous pregnancy such as a difficult birth or retained placenta can adversely affect the uterine environment in a subsequent pregnancy
  • Mare age - age related degeneration of the uterus and viability of the oocyte
  • Foal Heat mating - pregnancies established at the foal heat have a reduced viability and reduced conception rates
  • Twin pregnancies

Embryonic factors:

  • Genetic factors e.g. chromosomal abnormalities.
  • Small size, morphological defects.

Environmental factors:

  • Stress reduces progesterone production
  • Malnutrition of the mare and over or underfeeding in the period after mating can adversely affect her fertility
  • Any illness resulting in a high temperature or prolonged colic


Early embryonic loss may be predicted from the appearance on the ultrasound scan. The signs include:

  • An embryonic vesicle that is smaller than expected for its age
  • A vesicle with no embryo visible after the time when it should be seen
  • An embryo that is smaller than expected for its dates


Abortion is defined as the delivery of a dead foetus less than 320 days into gestation i.e. termination of pregnancy before the foal can survive outside the uterus. The overall rate of abortion in the horse population varies from 5-15%. If abortion occurs before 4 months the abortion is rarely noticed as the foetus is too small. Abortions can be caused by infectious or non-infectious factors.


  • Equine Herpes Virus (EHV) - usually abort late pregnancy i.e. over 7 months. Mare shows no symptoms. Can cause abortion ‘storms’ leading to in contact mares also aborting in same stage of pregnancy.
  • Equine Viral Arteritis (EVA) - usually abort in early pregnancy i.e. less than 3 months. Mares are usually sick and show symptoms of infection.
  • Placentitis (infection of the placenta) - bacterial or fungal infections of the placenta. This is the most common cause of abortions. Common infections are Pseudomonas Aeruginosa, Streptococcus Zooepidemicus, E.Coli, and Aspergillus Fumigatus.
  • Systemic infections/toxaemia.
  • Equine Infectious Anaemia (EIA)- abortions occur in last half of gestation. Low incidence rate.


  • TWINS - see below
  • Progesterone deficiency
  • Umbilical cord abnormalities, e.g. strangulated or twisted cord
  • Stressed mare
  • Malnutrition
  • Uterine torsion

What should I do if my mare aborts?

  1. Isolate mare - she may be infectious and may be a risk to other mares that are in foal
  2. Retain the aborted foetus and placenta (afterbirth) for the vet to examine

What will the vet do?

  • Take a history - the vet will ask a number of questions relating to the mare’s reproductive history e.g. stage of pregnancy, vaccination status, number of in-foal mares on the premises, health of mare, previous foaling history, clinical signs of mare before or after mare aborted, general feeding and management of mare. This will give clues to the reason for the abortion and will also be needed to forward to the lab with samples of the aborted foetus.
  • Examination of mare - full clinical exam will determine whether the mare is sick and requires treatment. Internal exam will be carried out to check for uterine tears, retained placenta, endometritis and presence of a second foal (twins).
  • Examination of aborted foetus and placenta - the appearance of the fetus and placenta can provide vital clues to the cause of the abortion e.g. fungal infections produce white plaques within the placenta, EHV infections produce jaundiced foetus with necrotic spots within the liver. Full examination of the placenta will ensure that there is no retained placenta still present within the uterus. Retained placenta is commonly seen in cases of abortion.
  • Submit samples to the diagnostic laboratory- the vet may decide to send the entire foetus and placenta to the lab, or may take a number of samples of the fetus including stomach and stomach contents, liver, lung, kidney, spleen, adrenal gland, placenta and uterine fluid.

The results of these examinations and tests will be vital, not only in diagnosing the cause of the abortion, but for recommending the correct treatment for the mare, risk assessment of other mares on the premises and also predicting the breeding future of the affected mare.


Twins are highly undesirable in the mare. If twins are not identified and treated in early pregnancy the usual outcome is abortion in late gestation. Nearly all twin pregnancies result from double ovulations. These may occur close together or several days apart within a single oestrous period. The incidence of double ovulations differs between breeds and increases with the age of the mare. Thoroughbred mares are reported to have a 15 – 25 % occurrence of double ovulations with a 15% incidence of twins.

Twinning is a serious source of loss to the breeding industry. Various reports suggest that between 53 and 73% of affected mares will abort and of all the mares with twin pregnancies, only 16-25% of mares will give birth to single or twin foals.
The cause of embryonic loss is the inability of the endometrium to provide adequate nutrition for both embryos. Twins located in the same horn are likely to die earlier in the pregnancy because the vesicles are in contact with each other rather than with the lining of the uterus and their nutrition is reduced.

Complications that can also arise with late term abortion or attempted delivery of twins include dystocia (difficulty giving birth), retained placenta, metritis and of course death of the twins. If twins are successfully delivered, they are usually underweight and require a great deal of intensive care. It is common for one or both of them to die within a few days of birth. Those that survive are less likely to achieve a high level of performance than single foals.

Diagnosis and treatment of twins:

Before day 35 of gestation-
Twinning is diagnosed by routine ultrasound examination per rectum. The best time to diagnose twins is at day 14-16 of gestation. At this stage, the conceptuses have not attached to the uterine wall and are also still small enough to manipulate. Usually the smaller of the conceptuses is gently moved away from the larger conceptus to the tip of the uterine horn, and is then squeezed between the ultrasound probe and endometrium until a ‘pop’ is felt. This can be a complicated procedure and should only be carried out by a vet. With experience, success rates can be as high as 90%. After day 17, the conceptuses attach to the endometrium, making it much more difficult to separate and crush one of the twins. Manual crushing of the twins becomes progressively less successful the longer the pregnancy is allowed to continue. Twins can be successfully squeezed up to 35 days gestation.

After day 35 of gestation-
Manual squeezing of one twin is impossible after day 35 and two options are available:

Very experienced stud vets may attempt to eliminate one of them by guiding a sterile needle through the wall of the vagina and into the foetal sac under ultrasound guidance.
Prostaglandin injections to abort both twins may be required after day 35. Around 35 - 40 days, endometrial cups have developed and are producing progesterone to maintain the pregnancy. Therefore, prostaglandin will cause abortion but will not remove these endometrial cups; hence the mare will still think she is pregnant even though the twins have been aborted. The mare will then not come back into season until the following breeding season.

Two pregnancy scans at days 14 - 16 then again at days 25 - 30 are imperative to successfully diagnose and treat twins without significant complications.

Abdominal wall hernias or prepubic tendon ruptures:

In late pregnancy the body wall is occasionally weakened by the combined weight of the foetus plus the membranes and placental fluids to the extent that it can tear. The muscle itself may tear or the prepubic tendon, which attaches them to the front of the pelvis. The signs include an area of oedema (swelling) up to 10-15cm thick extending along the ventral midline in front of the udder. The mare is often uncomfortable; she may show signs of colic and resent the area being touched. The udder may appear to have moved forwards.

The treatment is restricted exercise and non-steroidal anti-inflammatory drugs. A well-padded abdominal support bandage may be applied. Some mares are able to foal unassisted, but the abdominal wall is often too weak to push the foal out. An assisted delivery or caesarean section is likely to be required, so the birth should be supervised. It may be possible to repair the defect surgically, but this can very difficult. Further pregnancy puts the welfare of the mare at risk.

Early lactation (running milk):

Mares that run milk earlier than 2 weeks prior to foaling are classed as at risk. If this is observed a vet should be contacted immediately for further advice.

Premature lactation can be associated with impending abortion or placentitis and so the mare should be checked by the vet who may decide to examine the foal and placenta by ultrasonography. Measuring the combined thickness of the utero-placenta can identify a placentitis.  We can also measure the foals heart rate can determine whether the foal is distressed.

A more common complication of premature lactation is the loss of colostrum, which is vital for passive transfer of antibodies to the foal. During the first 12 hrs of life, the foal will absorb antibodies from the mare's colostrum, which will provide active immunity against infections as the foal matures. Loss of this colostrum can be severely detrimental to the foal.

What to do if your mare runs milk early:

  • Phone the vet for advice
  • Collect the colostrum in a bucket/container and freeze. This can be defrosted and carefully fed to the foal after birth
  • Make arrangements for alternative colostrum source - the vet will advise
  • After the foal is born, try to ensure adequate colostrum
  • Test the foal at 24 hrs old for IgG - this is a quick and simple blood test that the vet will take at the yard and will determine whether the foal has received enough colostrum

Lack of mammary gland enlargement and lack of milk:

Mammary gland development becomes apparent during the last month of gestation, especially in the last 2 weeks. A waxy yellow secretion will develop on the end of the teats 1-4 days before foaling. This is known as 'waxing up'. Maiden mares may not show mammary development until after foaling. If your mare is 1 week before foaling and has no evidence of any udder development then your vet should be contacted and preparations made for an alternative milk and colostrum supply in case no milk is produced. If the mare has already foaled and has no milk, the vet may give injections of oxytocin, which may stimulate milk let down.


Mastitis is an uncommon condition in a mare. It is characterized by a hard, enlarged, painful and hot udder. The mare may also show hind limb lameness and may have a high temperature, which may make her dull and inappetent.

Treatment includes intramammary and systemic antibiotics, regular milking of the mare's udder, hot packing the udder and pain killers.

Foaling box:

The mare should be moved to a foaling stud or a foaling box 4 - 6 weeks before she is due to foal. This gives her time to settle and ensures that the mare can build immunity to disease producing organisms in the new environment. She will produce protective antibodies, which are passed onto the foal in the colostrum.

The foaling box should be a minimum size of 3m x 3m (10ft x 10ft), ideally 5m x 5m (16ft x 16ft). The stable must be in a quiet, warm area; a temperature of 25 degrees Celcius is ideal. A clean, deep bed of good quality straw should be provided. Shavings are not thought to be as good as they can block the nostrils of a new-born foal and can cause problems for the recently foaled mare too. A power point and a means of providing a sick foal with warmth should be available. CCTV camera is very useful or if not a window so that the mare can be observed.  

Removal of Caslicks:

If the mare is stitched at the time of breeding this must be opened in preparation for foaling. This is done 1-2 weeks before foaling under local anaesthetic.

Basic Foaling equipment:

  • Clean towels ready to dry the foal
  • Lubrication if there is a problem foaling (lubigel)
  • Disinfectant (e.g. dilute iodine solution) to dip the foal's navel in immediately after birth
  • Thermometer
  • Access to hot water
  • Clean protective clothing including wellingtons
  • A tail bandage for the mare
  • Gloves
  • Scissors

Notify your vet:

Make sure that your vet knows that you have a mare expecting a foal and when it is due so that should you require some assistance they can be prepared for any eventuality. If you are uncertain about any part of the foaling process call your vet for help or advice before the foaling date.


Mammary development:

The udder of the mare begins to enlarge approximately 4 - 6 weeks before foaling. Most of the development takes place in the last two weeks when both the udder and the ventral abdomen can become oedematous. Drops of dried colostrum accumulate as waxy deposits on the teats 1-4 days before foaling, which are sometimes called candles.

These signs should not be taken as a reliable indication that foaling is imminent. Some mares show very little change until the last few hours while others run milk for days or weeks before foaling.

Change in mammary secretions:

The composition of the mammary secretions changes as the mare approaches parturition (foaling). If there is a particular need to know when foaling is imminent, the secretions can be tested, however these tests are still fairly unreliable. Milk strip test kits are available for measuring the electrolyte concentrations in the mammary secretions and may provide a guide to the maturity of the foetus and its readiness for birth.

Vulval relaxation:

Shortly before birth, the vulva lengthens and appears slightly swollen. Softening of the rump and tail head muscles can also be seen.

As foaling gets more imminent the mare may separate herself from the rest of the herd, act more nervous and go off her food. This usually indicates that the mare will foal within 24 hours.

As the foaling date approaches, the mare should be kept under close observation including at night. The observer should be familiar with the course of a normal foaling and call the vet if a problem occurs. At BELL EQUINE we use closed circuit cameras so the mare can be watched without being disturbed. Special foaling alarms are also available.

First stage labour:

During first stage of labour, the mare experiences discomfort from uterine contractions. The mare will exhibit signs very similar to colic including:

  • restlessness
  • sweating
  • pawing the ground
  • looking round at the flanks
  • lying down and getting up again and rolling - this is very important in helping the foal to reposition it self
  • milk may leak from the teats

The periods of discomfort are separated by periods of calm. Maiden mares may roll or become quite distressed. The length of first stage labour is extremely variable but usually ranges from 30 minutes to 4 hours!

Second stage labour:

Second stage labour lasts for an average of 20 minutes. It is usually a very rapid, explosive event once the mare lies down and begins abdominal contractions. It begins when the placenta ruptures and a large quantity of clear, pale yellowish fluid is released. This is the allantoic fluid. Most mares then lie on their sides and begin to strain. If the mare has a sutured vulva (following a caslick's procedure), which has not already been opened, it is vital that it is cut at this stage.

After 5-10 minutes, a white membrane called the amnion appears between the vulval lips. In a normal foaling the front feet are delivered first, closely followed by the muzzle. The mare continues to strain vigorously until the foal’s hips have been delivered.  She will then stop straining but stay lying down for up to 20 minutes. Do not disturb her especially for the first few minutes after foaling as blood is still passing from the placenta to the foal. It is quite normal for the foal’s hind limbs to remain inside the vagina and unless the amnion is obstructing the foal’s nostrils no interference is necessary. The umbilical cord breaks when the mare stands or the foal struggles to its feet.

Third stage labour:

The placenta is normally expelled within an hour of the foal being born. The mare may go down again and experience 'colicky' pain as it is delivered. If the placenta has not been delivered within two hours, notify your vet.

Induction of parturition

Mares are rarely induced to foal as the normal gestation period varies from 320-360 days. The foal matures in the last 2-3 days of gestation and there is no 100% reliable method of determining if this has occurred. Artificial induction before foetal maturation takes place considerably decreases the foal’s survival chances.

The procedure may be considered in:

  • mares with prepubic tendon rupture
  • cases where foaling problems are anticipated
  • cases where the mare or foal is considered to be at risk if the pregnancy continues

Complications of induction include:

  • the birth of weak or premature foals
  • premature placental separation. A thick red membrane (the allantochorion) appears at the vulval lips instead of the white amnion
  • foaling difficulties
  • retained placental membranes

Foaling Emergencies:

The majority of mares will foal unassisted without any difficulties. However, there are a number of situations in which immediate attention is required:

  • red Bag Presentation
  • recto-vaginal injury - foals leg through anus
  • dystocia
  • uterine inertia
  • vaginal laceration and herniation of intestine

Following the safe delivery of a foal the following checks should be made:

The foal:

Most foals are on their feet within an hour of birth. The foal should search for the teats and suck vigorously within 2 hours of birth. Most foals then suck 5-7 times per hour in the first few days. Veterinary attention should be sought if:

  • the foal gives any immediate cause for concern
  • it is not standing within 2 hours
  • it shows little or no inclination to suck within the first couple of hours following birth

The importance of colostrum:

Colostrum is the thick, yellow liquid in the udder when the foal is born. It contains antibodies that provide protection against infection and must be sucked by the foal within the first few hours of life. If the mare runs milk prior to foaling this essential protection is lost. Arrangements must be made to protect the foal in other ways. Contact your vet for advice.

Veterinary check - 24 hours Post Foaling Check:

A veterinary check of the new-born foal and mare is recommended. Any problems and weaknesses can then be dealt with at once. Things the vet may check include:


  • that the foal has a strong suck reflex, full tummy and is feeding well
  • IgG levels via a blood test - this is vital if there are any concerns that the foal may not have received adequate colostrum
  • the umbilicus and dip with dilute iodine solution
  • identify dummy foal
  • identify any congenital flexural or angular limb deformities
  • identify any other congenital problems e.g. cleft palate, congenital cataracts
  • identify any umbilical or scrotal hernias
  • the vet may choose to give the foal a tetanus antitoxin and antibiotic injectiona
  • a ‘fleet’ foal enema may be given to ensure meconium has been passed


  • check the udder to make sure the mare has plenty of milk
  • check the placenta to make sure all is passed intact
  • check the vulva and vagina for tears that may require suturing
  • check the mare is not bleeding

In Summary:

Arrival of the foal should follow 3 rules:

  • Within 1 hour: foal should stand
  • Within 2 hours: foal should suckle
  • Within 3 hours: placenta should be passed

There are a number of possible post foaling complications which require immediate veterinary attention. These include:

Retained Placenta:

The placenta should be passed intact between 30 minutes and 3 hours after the foal is delivered. If the placenta has not been passed by 2-3 hours then it is retained and is classed as a true equine emergency. Please call your vet immediately. The incidence of retained placenta in the mare is reported to be 2-10%, but can commonly occur as a consequence of:

  • Dystocia- difficulties delivering the foal
  • Twins
  • If the mare has a caesarian section


It is imperative that 100% of the placenta is removed. Even a small retained piece can result in serious complications. Bacterial multiplication within the uterus can quickly lead to septicaemia and endotoxaemia with a potentially fatal result. Severe laminitis is a possible sequel. Treatment is carried out by the vet. No attempt should be made to manually pull the placenta. This can result in serious complications such as uterine prolapse and tearing of the uterine arteries.

What the owner can do:

  • tie the hanging placenta into a ball just above the hocks - this prevents them from becoming torn and contaminated
  • gentle walking exercise may be helpful

What the vet will do:

  • Oxytocin injections will be given - this stimulates uterine contractions
  • the uterus can be infused with fluid - this often promotes expulsion of the membranes, together with any uterine contaminants
  • manual removal may be attempted by a vet who will take great care not to tear the placenta and leave a piece inside the mare

If the mare retains her membranes longer than six hours, urgent veterinary treatment is required. If she develops a temperature and becomes obviously ill she may need to be hospitalised. The uterus is flushed at regular intervals, intravenous fluids are administered, oxytocin, antibiotics and anti-endotoxic drugs are given and prophylactic laminitis treatment may be given.

Remember to note the time that the mare foals. If the placenta is passed, lay it out on the floor and check it is fully intact- call the vet if you are at all unsure.

Prolapse of the uterus:

This is uncommon but more likely to occur if the mare had problems giving birth, uterine trauma or if the membranes are retained. It tends to occur within the first few hours after birth. Uterine prolapse can be potentially life threatening if complicated by rupture of the large uterine arteries, if the prolapsed uterus becomes contaminated, infected and ischaemic leading to shock, septicaemia and death. This is a true equine emergency and your vet should be called immediately.

Treatment is focused on stopping the mare from straining with sedatives, epidural or sometimes general anaesthesia. The uterus is held up to prevent further traction, is cleaned, any bleeding vessels are clamped and any uterine tears are sutured. The uterus is then replaced if possible and fluid will be instilled into the uterus to ensure the tips of the horns are everted. Antibiotics and oxytocin will be given for a number of days.

Uterine tears:

These are more likely to occur if there are foaling problems and the delivery has to be assisted. Occasionally they can occur during an apparently normal delivery due to a foetal foot perforating the uterus.

Rupture of a major vessel:

The incidence of severe haemorrhage from rupture of a uterine artery increases with the age of the mare. Haemorrhage is usually internal so no evidence of bleeding from the vagina is seen. The mare often sweats and shows signs of extreme pain or colic. The mucous membranes quickly become pale and the condition is often fatal. Treatment can be attempted but if often unsuccessful.

Vaginal Haemorrhage:

May be caused by vaginal or cervical tears, trauma, forceful removal of retained placenta or varicose veins. Mild bleeding does not usually require treatment.

Rupture of the caecum:

This may occur due to the high abdominal pressures experienced during foaling.

Colon Torsion:

The most common cause of colic in the first 2 months after foaling is a displaced and / or twisted large colon. This occurs as uterine involution is taken place and more room is suddenly available in the abdomen that the foal previously occupied. The large intestines float around in the new available space and often displace or twist. The mare will present with sudden onset, severe unrelenting colic which is not improved with painkillers. Immediate veterinary attention, rapid diagnosis and immediate surgery are essential if the mare is to survive. Fatality is as high as 72%.