As breeding and foaling season approaches, it is important for horse owners and managers to understand the normal progression of foaling to ensure positive outcomes for all involved.

In horses, foaling — also called parturition — is the culmination of a gestational period that typically lasts approximately 320-380 days with an average of 338-345 days, although individual variation is considerable. Factors such as fetal maturity, nutrition, mare age and environmental conditions can play a role in length of gestation. Many managers will use 335 days (11 months) after the date of last breeding as a predictor to determine when to begin watching a mare more closely for signs of foaling. Due to the economic value of horses, precise understanding of parturition physiology and risk factors for complications is essential for those involved with breeding.

Prior to foaling you will need to work with your veterinarian to ensure your mare has received the proper protocol of vaccines to aid in passive transfer of immunity to the foal via the mare’s milk. Recommended vaccinations typically include tetanus toxoid, encephalomyelitis, West Nile virus, influenza and rhinopneumonitis with some variation depending upon specific situations. It is also recommended that mares are dewormed every two to three months throughout the pregnancy but read the labels to determine the if the anthelmintic of your choice is safe for use during pregnancy.

Your mare should be moved to the foaling location no later than a month prior to her expected due date and moved into the specific foaling area approximately a week before. If foaling in a confined space, straw in stalls, green grass in paddocks or large particle bedding is favored over small particle bedding such as shavings as it can hold additional bacteria and stick to the foal potentially increasing disease transmission. The week prior to foaling is a great time to bathe your mare, wash her udder and perineal area and remove any Caslick’s sutures if they were required.

Multiple changes will begin to occur in the mare indicating that she is getting closer to foaling. The mare will develop an udder, commonly referred to as bagging up, approximately two to four weeks prior to foaling, although maiden mares may not be as consistent with this symptom as aged mares. Calcium concentrations in mammary secretions will increase one to two days prior to foaling. Research has shown that mares with calcium concentrations less than 200 ppm have a less than 1% chance of foaling within 24 hours, but those with calcium concentrations higher than 200 ppm have a 97% of foaling within 72 hrs. These levels are easily detected with a do-it-yourself calcium concentration kit. Mares will also “wax” or build up a yellow honey-like substance on their teats one to four days before foaling. The abdomen will drop and the upper tailhead muscles can relax about a month prior, with the external genitalia and musculature under the tailhead becoming soft 12 to 24 hours prior to foaling. During the final hours before foaling, mares exhibit distinct behavioral changes including increased restlessness, frequent lying down and standing up, tail flagging, yawning and changes in locomotion patterns. Such behaviors can help predict the onset of foaling, although individual variability limits sensitivity.

Parturition is typically divided into three stages.

• Stage I - Uterine contractions and cervical dilation: During Stage I, contractions will move the foal through the cervix and into the birth canal, potentially exposing the fetal membranes. Stage I will end when the allantoic sac breaks and releases the allantoic fluid.

• Stage II – Fetal expulsion: Stage II and its duration are critical. This stage moves quickly (15-20 minutes after the mare’s water breaks). If this stage takes longer than 30-40 minutes, emergency intervention is recommended. Normal presentation of the foal is front feet first, one slightly ahead of the other with hooves pointed down. The nose, head, neck, shoulders and hindquarters should closely follow. If you notice any deviation from a normal presentation, call your veterinarian immediately. As the foal emerges completely, the inner sac usually breaks. If the sac does not break on its own, remove the sac from the foal and remove any debris from the nose and mouth. If your foal is having difficulty breathing, rub the foal vigorously with a towel. If possible, allow the foal to lie quietly behind the mare for 10 to 25 minutes until the remaining blood from the placenta is transferred. Then crush the navel cord and separate it about 1 inch from the body and dip in an antiseptic like chlorohexidine. The use of antiseptics is encouraged to assist in drying the umbilical stump to prevent infections.

• Stage III – Placental expulsion: Stage III begins after the delivery of the foal and ends when the placenta is expelled. This process can take one to three hours. If the placenta is not delivered, medical attention is necessary as a retained placenta can lead to serious infection or laminitis. Once the placenta is delivered, check for any missing pieces or abnormalities.

Within 30 minutes of birth, the foal should begin attempting to stand and nurse. This time frame can be very frustrating to watch as it can take some foals a while to figure out; however, most foals will nurse successfully within three hours of birth. This first milk or colostrum contains valuable antibodies and delivers passive immunity to the foal. If colostrum has been delayed longer than eight hours, it decreases the foal’s ability to fight off infection. Studies of foal gut colonization following birth highlight the importance of early feeding and maternal contact in establishing healthy microbial communities, which are crucial for immune development. Many horse owners will choose to have the foal’s immunity (IgG levels) tested within 12-24 hours of birth and give plasma as an added precaution. Foals should pass their first bowel movement (meconium) in eight to 12 hours. It is important to keep a watchful eye on your mare and foal for the first 48 hours but only intervene if necessary to reduce stress and allow time for adequate bonding. Healthy mares and foals can be turned out into a larger paddock after two days and integrated back into a herd of other mares and foals within the week.

Foaling is a complex physiological process that requires attention to preparation, observation and timely intervention to ensure the health of both the mare and foal. While there are instances where medical attention is required, many foals are delivered without emergency or requiring major intervention. If you are expecting a foal and are unsure of your ability to manage their needs adequately, discuss your options with your veterinarian.