The Mare During Pregnancy

18th October 2017

The Mare During Pregnancy


The aim is to increase the level of nutrition in the last 3 months of pregnancy. A brood mare should not be allowed to become too thin or too fat. The diet for the last stages of pregnancy should be a proprietary brood mare diet; this will include the correct balance of minerals and nutrients for foal development. Follow the manufacturer’s guidelines initially then feed by eye resulting in a gradual increase in weight prior to foaling. If your mare is getting too fat on a brood mare diet then please call for more specific advice for your individual circumstances.


It is usual to remove the mare’s shoes when foaling becomes imminent, to lessen the damaged caused if the mare stands on the foal. Some mares may become foot-sore without shoes; take veterinary or your farrier’s advice. It is important to maintain hoof health with regular trims.


Ideally your mare should be following a worming program recommended by your vet. In the last month before foaling your mare should be wormed with an ivermectin based product, such as Eqvalan or Bimectin. This is because some worms can cross the mares’ uterus and others can also cross into the mares milk and infect the foal. Foals will also eat the mares dung as a normal process during the first few months of life so good mare worming is essential.


1. Influenza and tetanus vaccination status should be up to date (i.e. FT1, FT2 between 21 and 92 days later, FT3 between 150 and 215 days later, then annual boosters). The mare should be given a booster vaccination within the last month of pregnancy, to boost the level of flu and tetanus antibodies in the colostrum for the foal.

2. Vaccination to reduce the risk of abortion caused by Equine Herpes Virus 1 (EHV1) can be performed at 5, 7 and 9 months of pregnancy. Mares at risk of EHV1 abortion are those at yards where horses are coming and going and thus may bring in infection or mares who will be in contact with yearlings and young horses.

3. Vaccination to increase the foal’s colostrum derived immunity to diarrhoea caused by Rotavirus infection can be performed at 7, 9 and 10 months of pregnancy.

Swabs and Blood Samples

If your mare is going to foal down or to be covered after foaling at a stud, there may be requirements to have her swabbed for Contagious Equine Metritis (CEM) and to have a blood sample taken to test for Equine Viral Arteritis (EVA). These can be taken prior to foaling; it is essential to check with the stud what is required.

Caslick’s Vulvoplasty

Some mares require their vulva to be stitched (Caslicked) in order for them to conceive, this is because air and bacteria are sucked into the vagina as a result of a poor vulval seal. Prior to foaling it is essentially that the Caslicks is reversed in order to prevent tearing of the vulva and anus as the foal is born. This is typically done when the mare starts to show significant signs of mammary gland development. Some mares such as maiden mares give little warning of imminent foaling as such it is better to have the Caslicks reversed sooner rather than
leaving it to the last minute. In order to plan the best time to perform this task please contact the practice and discuss this with your usual vet, it can usually be tied in with one of the other pre-foaling visits.

Stable and Paddock Preparation

Once your mare is in foal it is important that the last few months of the pregnancy are well planned. The length of pregnancy in mares is highly variable (330 to 370 days), a rule of thumb is that the due date is 11 months plus 1 week from the last covering date. Mares can be foaled out in a paddock, particularly if the weather is likely to be good at the time of foaling. Most mares foal at night and as such a stable environment may be preferable as this allows ease of observation. If the mare is to foal in a paddock then a suitable stable should be available in the event of a complication.

The stable should be secure and as clean as possible with a comfortable straw bed. Good lighting and clean water should be available. Ideally a small well fenced nursery paddock, close to the stable should be provided for turn out during the first few days and weeks of the foal’s life. The paddock should be clean and level, without any hazards, and preferably rested prior to foaling.

Ideally mares should be moved to their foaling site at least a month before foaling. This will minimise any stress and will allow the mare’s immune system to respond to any pathogens in the new environment. Hopefully this new specific immunity will be passed on to the foal in the colostrum.

Mare Monitoring

Most mares foal without complication; however, it is important that they are monitored regularly as the foaling becomes imminent. Mares prefer to foal when all is quiet, as such it is important that the checks do not disturb them. The stable can be fitted with a low wattage light bulb that can be left on. Small cameras are available so that foaling mares can be observed from a distance and sweat alarms can be used to indicate an imminent labour. In high-risk mares with complications, the milk secretions can be monitored to more accurately identify when labour is likely to begin.

Signs of Impending Foaling

The mare herself will start to show signs impending foaling. These may occur several weeks before foaling or may start much closer. The signs include development of the udder, swelling in front of the udder, slackening of the pelvic ligaments resulting in hollowing and softening of the quarters, lengthening and relaxation of the vulva, changes in temperament and the production of wax on the teats. The “waxing-up” of the mare is one of the last signs to occur.

Colostrum Wastage

During the last month of pregnancy the udder produces the first milk, colostrum, this is rich in antibodies that protect the foal from infection. Prior to foaling some mares drip or run milk and as a result lose the valuable colostrum, once lost it is not replaced. If this occurs 200ml volumes can be milked from the mare and frozen, this stored colostrum can be thawed in warm water (not microwaved) and bottle-fed to the foal in the first 6 hours after foaling.

The Three Stages of Labour

While a mare is foaling, it is better to minimise interference and to only respond when there is a problem. There are three stages of labour. The first stage is when the foal is getting into the correct position to be born, this may take several hours. During this time the mare may become restless, sweat, look at her flanks and get up and down. The second stage of labour begins with the passing and breaking of the water bag, it ends with the complete birth of the foal. Ideally mares should foal lying down. The second stage of labour involves the forceful uterine and abdominal contractions required to give birth to the foal, typically the mare will be lying on her side.

Once the foal’s head has been passed it may be necessary to clean any membranes from the nostrils. The average length of the second stage is 17 minutes, if after this length of time when forceful expulsive efforts have been made and the foal has not been produced veterinary assistance should be sought. The third stage of labour involves the passing of the placenta. Once the mare stands after foaling the placenta should be knotted at the level of the hocks to prevent the mare from standing on it. The placenta is usually passed within one hour, if it is not passed within three hours veterinary assistance will be required. The placenta should be kept for your vet to examine.

The First Few Hours of the Foal’s Life

Once the foal has been born, if all is well, the mare will usually lie quietly on her side or siting on her chest for a few minutes. During this time the foal’s hind legs will probably still be in the birth canal and the foal’s umbilicus will still be attached to the placenta, as much blood from the placenta, as possible will be retained by the foal. The umbilicus will break at a natural weak point when the mare stands; it should not be cut or clamped. Once the cord has broken it should be treated with a 0.5% chlorhexidine solution or liberally sprayed with antibiotic spray. After a few minutes the foal can be pulled, on its back by the front legs, under the mare’s nose for her to lick. It is essential that the mare-foal bond be firmly established in the first few hours after foaling, thus minimal interference is recommended.

Foals generally stand within the first 30 to 60 minutes and very quickly hunt for the milk bar. The first suckle is usually observed within 2 hours. With minimal interference the foal may need gentle steering in the direction of the udder. Some mares may need to be restrained to allow the foal to suckle for the first time. If the foal does not suckle within 4 hours veterinary advice should be sought, the best time for absorption of colostrum is in the first 12 hours. The best time for a veterinary surgeon to check that the mare and foal are healthy is between 12 and 18 hours after foaling.

The first faeces, the meconium, are usually seen within 6 hours of foaling. Impaction of the meconium is the most common cause of colic in new-born, particularly colt, foals. The first urination is usually observed around 8 hours after foaling. It is important to try to observe and record the normal bodily functions and behaviour of the foal, as this will help the vet with the diagnosis of a problem, if one arises.

If there are any problems during the foaling, involving the passage of the placenta or with the foal once it has been born please contact your vet sooner rather than latter, even if it is just for reassurance.


Post-foaling Vet Check of Mare and Foal

As long as there are no complications associated with the foaling the ideal time for the vet to check the foal is between 12 and 18 hours of age. There will be a full clinical examination of both mare and foal. Advice will be given on any congenital problems, such as limb deviations and navel hernias.

It is possible for the vet to check that the foal has obtained enough colostrum, to protect it from infection, by collecting a blood sample and measuring the IgG level. This is usually performed at the initial foal check. To assist in the prevention of tetanus foals are given a tetanus anti-toxin, this is not a vaccine.

Examination of the placenta is important to check firstly that it is complete and also to look for abnormalities that may indicate problems with either mare or foal.

Future Mare Management

After foaling it is important to observe the mare for signs of a problem. Signs may include mild colic, off colour, off food and a temperature.

If your mare is to be covered again this season, the first heat after foaling is important. This is the time that the reproductive tract can be re-checked for post-foaling trauma and a uterine swab can be taken to ensure she is free from bacterial or fungal infections after foaling. This further post-foaling check is usually carried out 7 days after foaling. If infection is present the mare can be treated at this stage with a view to covering her at the next heat. Also, if the mare was stitched (Caslicked) for the pregnancy then ideally, she should be re-stitched.

The time to the next heat can be reduced by short cycling the mare with a prostaglandin injection, typically given 20 days after foaling.

Future Foal Management

It is usual to allow the mare and foal out in a small nursery paddock the day after foaling, as long as the foal is strong enough, the weather is good and your vet feels that it is appropriate. The first few weeks of the foal’s life are very important, every effort should be made to detect signs of illness or problems as early as possible. Limb conformational defects should be dealt with under veterinary supervision as promptly as appropriate. Regular farriery will be required for both mare and foal.


The foal will initially obtain most of its nutrition from the dam’s milk. It will start to pick at hard feed and grass mimicking its mother. At this stage it may be appropriate to provide a proprietary creep feed or use a suitable mineral supplement.


The foal should be wormed at monthly intervals from 1 month of age preferably using an ivermectin product such as Eqvalan or Bimectin. At 6 months of age the foal can be given a wormer to include tapeworm and then be slotted into your standard worming program. Pasture management, including picking up of droppings is important to minimise the worm challenge to the foal.


Foals can be vaccinated for tetanus from 3 months of age and influenza from 5 months of age. It is usual to combine the 2 vaccines and give both between the 5th and 7th month of age. If the foal has a wound or foot abscess before it has been fully vaccinated for tetanus it is advisable that a second injection of tetanus anti-toxin be administered. Foals can also be vaccinated for EHV1,4 from 5 months of age, if necessary.

Foal Heat Diarrhoea

A point to note is that the majority of foals will have a bout of mild diarrhoea around the time of the mare’s first heat. This is associated with physiological changes in the foal’s digestive system. As long as the foal does not go off the suck or become dehydrated, then the only treatment required is to keep the foal’s rear clean. It may be necessary to apply baby oil to the skin to prevent scalding. If in doubt then please contact the practice for advice. Administering oral pro-biotic preparations in the first few days of the foal’s life can reduce the degree of “foal heat scours”.