Care of the Expectant Mare
Care of the expectant mare
If you are expecting your mare to foal this year, it is important to plan well in advance. The vast majority of mares (even maiden) foal without difficulty and produce a healthy foal. You do not need to worry about the event, but you should be well prepared!
Pregnant mares should be separated from other horses on the farm to limit transmission of diseases that potentially could have a detrimental effect on pregnancy. Exercise should be encouraged during early to mid-pregnancy, and grazing generally provides adequate exercise in most cases. Stress should be avoided as much as possible. Routine dental care and foot care should be provided as needed, but we generally recommend that annual dental examinations and procedures be performed after the mare has foaled and before she is put back into foal to avoid the stress related to these procedures and to avoid sedation while pregnant. Pregnant mares should be transported only when necessary. The mare should be moved to the foaling stud at least 10-14 days prior to the calculated foaling date, to minimise stress close to the time and to allow her to acclimatise. This will also expose the mare to any pathogens present in the new environment and give her time to build up antibodies, which will be passed on to the new born via the colostrum.
Nutrition and feeding management
Pregnant mares should consume enough nutrients to both maintain their own body weight throughout the pregnancy and guarantee the foetus development.
The pregnant mare feeding’s programme should be divided into three separate stages, each of which characterised by markedly different nutrient requirements. Stage one is early pregnancy, from conception through the first five-seven months of gestation. At this stage in pregnancy, unless she is lactating, the mare can be fed essentially the same as if she were not pregnant at all. The foetus, in fact, grows very slowly during this time (0.2 pound/day), therefore it is just necessary to meet the mare’s nutrient requirements for maintenance. An ideal diet may comprise of pasture alone with the addition of a vitamin and mineral supplement (e.g. Stud Balancer) to balance nutrient shortfalls in the pasture. Obviously if pasture is poor or scarce, additional hay or chaff should be fed a rate of at least 1-1.5% bodyweight per day or ad libitum if hay quality is average to poor. Starting from the 6th month it is advised to gradually increase the nutrient requirements, in order to prepare the mare to the higher necessities required during the last phase of pregnancy. Stage two encompasses the last trimester of pregnancy, which is from around seven months of pregnancy through foaling. At this stage the foetus begins to grow rapidly (1 pound/day). Additional energy in the form of concentrate feed (e.g Stud Mix or Stud Cubes) may be required to meet the demands of the unborn foal and provide reserves to prepare the mare for lactation. Grain intake should be increased gradually during the last few weeks of pregnancy so that the mare is consuming nearly the amount that’s she will require for milk production at the time that she foals. A rapid increase in grain should be avoided at foaling time because this may lead to colic or laminitis-associated issues. Stage three is lactation, which generally lasts five or six months after foaling. Mares in early lactation may require up to 8 kg of grain per day depending upon the type and quality of forage they are consuming, but some mares can be successful milkers on good pasture and a vitamin and mineral supplement alone. The aim should be to use the best quality forage and keep grain levels down to avoid potential digestive upset. The grain portion can be administered in the form of a complete mixed feed to ensure balanced and convenient nutrition.
*The most common mistakes made in feeding broodmares are overfeeding during early pregnancy and underfeeding during lactation!*
Brood mares should be up to date with tetanus and equine influenza vaccinations prior to conceiving. A booster is then given 4 to 6 weeks before the due date, which will result in an increase concentration of antibodies being transferred to the foal via the colostrum.
Vaccination against Rhinopneumonitis caused by Equine Herpesvirus Type 1 (EHV-1) is particularly important for the pregnant mare since infection can result in abortion. EHV-1 is highly contagious, with transmission usually occurring through the respiratory route. Exposure to horses shedding the virus, or reactivation of the latent virus with the stress of pregnancy can result in infection; the virus can cross the placenta and cause the foal to be aborted. Abortion can occur from 2 weeks to several months after infection. Abortion usually occurs in late pregnancy but can occur as early as the 4th month of pregnancy. If a mare is infected during late pregnancy, her foal may be stillborn or born alive, but die within a few days of birth. It is recommended that mares be vaccinated against EHV-1 in the 5th, 7th and 9th month of her pregnancy. In higher risk situations where your mare will have exposure to non-vaccinated horses or horses that travel, it is recommended that the first EHV-1,4 immunisation be given at 3 months.
Routine deworming of the pregnant mare throughout gestation will decrease the exposure of the new born foal to parasites. Therefore, your mare should be dewormed regularly, according to the individual requirements of the farm or yard and monitored by periodic faecal examinations to determine parasitic egg levels, with the last treatment occurring 4-6 weeks before her due date. Of particular relevance is the nematode Strongyloides Westeri, which can cause diarrhoea, usually in the first weeks of life. Most serious infections arise via milk from previously infected mares. Therefore, it is advised to worm the mare with Ivermectin just before foaling (24-12 hours) to prevent lactogenic transmission, unless the mare has been recently treated with a macrocyclic lactone product.
Early in gestation, some mares require a Caslicks operation to partially suture together the lips of the vulva. Caslicks are used to prevent problems in mares that have abnormal vulva conformation. Mares that have a Caslicks must have the lips of the vulva opened at least 30-15 days prior to foaling. If the Caslicks is not opened, there is the possibility of oblique tears to the vulva or vagina which are difficult to repair and may result in a deformity that leads to uterine infection.