Preparation of your Mare for Foaling

Once your mare is in foal, preparation begins for foaling several months ahead of her due date. Typically, equine pregnancy ranges from 330-345 days. Length of the equine pregnancy is extremely variable, although many mares will have a similar gestational length in subsequent pregnancies. Mares can go significantly over their due date and produce a healthy foal; however less than 330 days is considered premature. Mares who have previously experienced complications or had a premature foal are deemed high risk.

Pregnant mares should have a consistent and low stress environment and good access to pasture. Body condition should be monitored throughout pregnancy and kept as moderate to moderately well. Body condition can become more difficult to assess in late term pregnancy when the abdomen changes shape with the weight of the foal and foetal fluids, especially in mares who have had several foals. It is not unusual to see rib, so close inspection of key areas for fat deposition is essential (crest, shoulder, croup and head of the tail). Overfeeding and obesity may lead to metabolic and orthopaedic issues and can make delivery more difficult.

Most of the growth of the foetus occurs in the last trimester, and so until this point your mare’s energy intake can be kept in line with what is normal for her, unless her body condition is changing. Most of her diet should be fresh pasture or forage, but throughout pregnancy a fortified pelleted feed, designed for pregnant mares and balanced with appropriate energy, vitamins, and minerals, should be included. Pasture alone may be lacking in certain essential minerals for both mare and foal. Changes in routine and diet should be implemented gradually over one or two weeks. Mares should be in a positive energy balance at foaling, allowing for the high metabolic demands of this. Free access to fresh water should be always available. 

Pregnant mares should not be mixed with young stock or new arrivals due to the risk of infectious diseases, including Equine Herpes Virus. Mares who are up to date with vaccinations should receive a tetanus and strangles booster (2 in 1) 4-6 weeks prior to foaling to enhance colostral immunity, and additionally a Salmonella booster at this time. If your mare is not already vaccinated, or you are unsure of her vaccination history, you should speak to your veterinarian early in her pregnancy to formulate a plan. Equine Herpes Virus 1 and 4 vaccines can be given to help protect from herpesvirus mediated abortions, and severe illness in neonatal foals. These are given as a single shot at 5,7 and 9 months of gestation. Rotavirus vaccination can be given to help protect your foal from diarrhoea caused by rotavirus. This is given at 8, 9 and 10 months of gestation for the primary course, and one shot a month before foaling in subsequent pregnancies.

Check if your mare has a caslick in place, as this should be removed prior to foaling to avoid tearing of the vulva and allow easier delivery of the foal. The caslick should be removed approximately two weeks before foaling.

Throughout your mare’s pregnancy, vaginal discharge is an important sign to be aware of. It can be a symptom of infections of the genital tract and placenta or may be a sign of abortion or premature delivery. Always call your veterinarian for investigation. They may wish to perform a physical exam of your mare and an ultrasound examination of the reproductive tract or abdomen.

Udder development usually occurs 2-4 weeks prior to foaling. It is possible to detect impending parturition by measuring milk calcium if you can easily collect mammary secretions. pH of mammary secretions can also be used to predict parturition. Maiden mares may have limited udder development or secretion prior to foaling. Premature udder development or running of milk may be linked to a placentitis or impending abortion. This should be investigated by your veterinarian. Teats usually become engorged approximately 4-6 days prior to foaling, and mares will ‘wax’, where a yellowish substance appears at the tips 1-4 days prior to foaling. Relaxation of the tail head and lengthening of the vulva can also be observed.

It is not uncommon for late term mares to develop a ventral oedema, which is pitting fluid under the abdomen. This usually extends from the udder towards the most dependent point of the abdomen. This can put mares at a higher risk of pre-pubic tendon rupture or abdominal wall hernias, so it is worth consulting your veterinarian.

Mares should be moved to their foaling location at least one month prior to their due date. This is to develop colostral antibodies that are suited to the specific infectious challenges the foal will face when born. Foals do not receive antibodies across the placenta from the mare, so are dependent on colostrum for immunity at birth.

Ideally the mare should foal down in a stall or small yard, and it should be sufficiently large to allow the mare to get up, lie down and move around during foaling. As a rough guideline, a size of 3.5 x 5 metres is considered adequate. Straw bedding is preferable to shavings as the small size of shavings may stick to the wet foal, contaminate the reproductive tract, and can harbour bacteria such as Klebsiella species.

In stables, appropriate drainage is necessary to avoid the floor becoming excessively slippery with the expulsion of foetal fluids. Bedding should be removed, and walls sprayed with a disinfectant solution such as chlorohexidine after foaling, if another mare is to foal down in this box. If a small paddock is being utilised for foaling, the fencing should not allow the foal to slip underneath and become separated from the mare. This can be highly stressful for both mare and foal and deprive the foal of milk/colostrum.

If you are foaling down at home, consider the use of a foaling alarm and cameras to help you monitor the mare. Ensure that you have a foaling kit ready to go, including veterinarian phone number, long waterproof gloves, umbilical clamp, disinfectant, towels, a bin bag for the placenta, scissors to break open membranes, if necessary, a flashlight/ light source, a watch, sterile lubricant, and foaling chains if you are trained in how to use these. Also ensure that you have an emergency plan in place, including transport, in case of dystocia, premature placental separation (red bag), post foaling complications or a neonatal emergency.

Written by Dr Emma Saric