Foaling Fundamentals: The Top 10 List By Patrick M. McCue, DVM, Ph.D.,
Diplomate American College of Theriogenologists
Gestation Length
of horses is approximately 340-345 days. The length of pregnancy is about 7-10 days longer for mares foaling out in the winter than for mares foaling out in the late Spring or Summer. Mares maintained under lights during the last few months of pregnancy will have a shorter length of gestation. One should factor in season and light exposure when calculating expected foaling dates. Pregnant mares should be vaccinated one month prior to the due date to increase antibody levels in the colostrum. Type of vaccine administered may depend on geographical location, potential exposure and management practices. If the mare has had a Caslick procedure performed, the sutured vulva should be opened approximately 2 weeks prior to the expected foaling date or earlier if needed.
Milk Calciumlevels increase as the time of foaling approaches.
Most mares foal within 48 hours of when milk calcium levels reach 200 ppm. Several commercial test kits are available to help predict when foaling will (or will not) occur.
Waxing of the Teats
Waxing of the Teats
is a sign that foaling will occur in most mares within 24 to 48 hours. However, not all mares wax up and the duration from the onset of waxing to foaling can be quite variable.
Stage 1 of Labor lasts for 1-4 hours. Signs of early labor in the mare include frequent episodes of lying down, looking at her
flanks, pawing at the ground and patchy sweating. The end of Stage 1 occurs when the mare 'breaks her water' or ruptures the outer placental membrane (chorioallantois) and releases allantoic fluid.
Stage 2 of Labor or active labor lasts 20 to 30 minutes. The first
structure visible at the vulva should be the amnion, a translucent gray membrane. The hallmark of premature separation of the placenta ('red bag') is the appearance of a thick, brick-red, velvety membrane
(the chorion) at the vulva during early labor. Red bag should be considered a medical emergency as the oxygen supply to the foal is compromised and veterinary help should be summoned immediately.
Establishment of an Airway and Stimulation of Breathing is the top priority when a foal has just been born. The amnion should be
removed from the nasal area if it did not break spontaneously during foaling. Respiration may be stimulated by briskly rubbing the newborn foal with a towel, tickling the inside of the nostrils with straw
or flexion and extension of the front limbs to stimulate stretch receptors.
Dip the Navel with a disinfectant soon after foaling to help prevent
bacterial infections and help seal the umbilical stump. Common disinfectants include dilute Nolvasan, Betadine and Iodine. It is
recommended that the navel be dipped 2-3 times per day for the first 2-3 days after birth.
Standing and Nursing by the foal should occur within approximately
1 hour and 2 hours, respectively, after birth. Ingestion of colostrum, which is rich in antibodies, is critical for early immune protection of
the foal. Ideally, a liter or more of good quality colostrum should be ingested by the foal within the first 6-12 hours of life. Antibody (IgG)
levels in the blood of the foal may be checked 24 to 36 hours after birth to determine if adequate transfer of colostral antibodies has occurred. However, if blood antibody levels are checked earlier (i.e.
at 12 hours), oral supplementation with frozen-thawed colostrum or a colostrum substitute can be administered if needed. Several commercial diagnostic tests are now available for measuring IgG
levels in foals to determine the success of passive antibody transfer. Evaluating antibody levels is a critical component of an optimal health
program for newborn foals.
Passage of the Placenta (Stage 3 of labor) should occur within 3
hours after foaling. Failure to pass the placenta could lead to severe medical conditions in the mare, such as peritonitis and laminitis (founder). Early
Mare and foal.
medical intervention can aid in stimulating passage of the placenta and prevention of subsequent complications.
Meconium or first feces should pass within approximately 3 hours after birth. An enema should be administered if a foal
strains to defecate without passing meconium. Commercial phosphate-based enemas (i.e. Fleet) are safe, effective and convenient. .
About the Author...
Patrick M. McCue, DVM, Ph.D., Equine Reproduction Specialist Associate Professor, College of Veterinary Medicine
and Biomedical Sciences, Colorado State University
