The Science of Horse Racing: Foaling the Future

The early months of a new year bring on a slew of special photos, the earliest portraits of the Thoroughbreds we come to know and love.

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Daily, we will see newborn horses pictured in the straw with their dams and smile at the videos of hours-old babies taking their first steps on spindly, uncertain legs. In the days that follow, dams and foals will dot paddocks across the country, an eternal example of the continuity of life. The youngest of Thoroughbreds will race across the grass and stop for a snack as their mothers go about the business of teaching them to be horses.

As we celebrate this new season of life, let’s look at the process of foaling and how our favorite racehorses went from safe inside a broodmare’s womb to taking their first steps toward greatness.

The Process Begins

She has been in foal for months. Her owners agonized over the choice of stallion for this year and her veterinarian and carers made sure she was physically ready to breed. Her vaccines have been updated and her heat cycles, the days each month when she is the most fertile, have been regulated. They sent her to another farm to visit that stallion and hoped that the cover is successful. She returned to her home and then had a veterinarian scan her to check that she was in foal. The ultrasound showed that their mare is pregnant and now, these many months later, her foal is due soon.

A horse’s pregnancy, or gestation, lasts about 340 days, around eleven months. In the weeks leading up to foaling, a mare’s udder, which has two teats, will start to fill with milk in anticipation of the baby to come. This phenomenon is called ‘bagging up,’ as the hormone progesterone, which kept the developing foal safe inside her womb, gives way to prolactin, a signal that the mare’s body is preparing for delivery. In the days immediately before giving birth, white waxy build-up on the teats is a signal at the mare is producing colostrum, the nutrient- and antibody-rich milk that a newborn foal needs in the hours immediately after birth.

Additionally, as the mare’s body prepares for foaling, the muscles in their hindquarters will relax. Hormones like relaxin prompt the ligaments over her pelvis and those under her tail to change, giving her backside a dropped appearance. Her humans will wrap her tail to help keep the area clean for the foal to come. In her stall, the mare will move her bedding around as if she were creating a nest and then pace or appear uncomfortable. These actions signal the start of labor.

In a roomy stall with plenty of space for the mother to labor and give birth, the months of waiting are almost over, but the process of bringing that new life into the world is just beginning.

The First Stage

In the first stage of labor, a mare will go from standing to lying down and back several times, possibly to help reposition the foal within her birth canal. She will look at her abdomen, much as a horse might do during colic, and even bite at the area, a sign that contractions are growing more intense and more painful. In her stall, as her handlers monitor her progress, she might urinate more frequently as the foal puts pressure on her bladder. Over the hour or so, the white membranes surrounding the foal will become more visible as he moves through the birth canal, putting pressure on them. When those membranes rupture and releases the allantoic fluid, it is a signal that the new foal will arrive within minutes.

Though they will be close by, her human helpers try to stay out of the way. They will check to make sure that nothing is amiss, monitoring her via a closed-circuit television system and then checking her in person. If the bag that peeks out of her birth canal is red rather than white, that means the placenta is coming out with the foal, a situation that requires veterinary assistance. The humans will check that the foal is presenting in the right position for a smooth birth; if the foal is not in the right position, a veterinarian will need to intercede.

As soon as the membranes rupture, her labor accelerates. First, one tiny hoof appears, then a second, and then the nose will peek through. Then the foal starts to emerge almost as if diving headfirst out of the mare. The head, neck, shoulders, and hindquarters appear quickly as the mare pushes the foal out. Finally, this new life is greeting the world still wrapped somewhat in the membrane that kept him safe in the mare’s uterus and attached to the mother via the umbilical cord.

Soon, the cord will separate spontaneously, and the foal is now functioning on his own. As the mare begins to clean her baby, the placenta is delivered. The birthing process is now complete as the focus turns to caring for both mare and foal.

A New Life Emerges

In addition to being covered in the allantoic fluid that he swam in throughout the months of development, a foal is born with an eponychium, or a capsule of white layers of soft keratin surrounding each hoof. These layers look like fingers, hence the nickname “fairy fingers,” and are designed to prevent the foal’s sharp hooves from piercing the mare’s uterus during pregnancy.

Within the first hour or so after birth, the foal should find his feet, standing and even walking relatively quickly, as a prey animal like a horse should do. This will wear the eponychium off the foal’s hooves as he finds his feet and starts to run. Within the first day or so after birth, the “fairy fingers” will be shed completely and the new foal will be trotting and galloping like an old pro. Any delays in these milestones means a visit from the veterinarian as well.

Soon, this new life is suckling at his dam’s teats, taking in the colostrum he needs to start building his immune system. Human helpers will handle the foal as well so that the new horse will understand that these two-legged creatures are friends, not foes. They will dip the umbilicus, where the cord separated from the foal’s body, in tamed iodine to help it heal. As mother and baby bond, their carers will make sure the foal urinates and passes meconium, that first bowel movement, within the first 8-12 hours of birth.

The Joys of This Season

From now until weaning around four to six months, mare and foal are inseparable, mother teaching her baby what he needs to know to be a horse. Along the way, these moments are captured in photographs or videos, mementos of those earliest days of this special foal’s life.

As you scroll through your social media feeds and smile at the photos of new foals lying in straw, think about the process that your favorite mare went through to be here with her baby. She had humans nearby when she was paired with the stallion chosen for her and more helpers watching closely as her foal pushed his way out of his dam’s body. Marvel at the long months turned to quick hours as this baby becomes a part of the sport we love, the hopes of many a breeder, caregiver, and fan centered on those tiny hooves finding their footing in their new world.