A nurse mare is a lactating horse brought in to feed and raise a foal that isn’t her own. The practice exists because some mares die during foaling, reject their newborns, or can’t produce enough milk. In the Thoroughbred racing industry, nurse mares also step in when a valuable broodmare needs to be re-bred quickly and her own foal would delay that timeline.
Why Nurse Mares Are Needed
Foals depend on their mother’s milk for the first several months of life, and the first milk (colostrum) delivered within hours of birth carries antibodies essential to a newborn’s immune system. When a mare dies during or shortly after delivery, the foal faces an immediate survival crisis. Rejection is another common trigger: some first-time mothers refuse to let their foals nurse, and repeated attempts to intervene don’t always work.
The Merck Veterinary Manual states plainly that a nurse mare is the best option for the overall care of an orphan foal. Alternatives like cow’s milk, goat’s milk, or commercial milk replacers can keep a foal alive, but they come with digestive risks including diarrhea, constipation, and colic. Goat’s milk is higher in fat and energy, which makes it easier to digest than cow’s milk, but it carries a higher chance of constipation and metabolic problems. None of these substitutes replicate the social learning a foal gets from being raised by another horse.
Where Nurse Mares Come From
Nurse mare providers maintain herds of mares that are bred specifically to produce milk. A mare must give birth to begin lactating, which means every nurse mare has her own biological foal. When a client needs a nurse mare, the provider selects a mare whose temperament fits the job. Providers look for mares that stay relatively calm when separated from their own foal and readily accept a stranger’s offspring. Not every mare has this disposition, so selection over time shapes these herds toward calmer, more accepting animals.
This is also the part of the industry that draws the most criticism. It’s a tragic irony, as one equine publication put it, that a business created to save valuable foals makes orphans out of others. The nurse mare’s biological foal is removed so the mare can be shipped to the client, and that foal then needs to be raised by hand or placed with a rescue organization. For years, this wasn’t something people in the industry spoke about openly. Practices have improved over time, with more rescue networks dedicated to raising these so-called “nurse mare foals,” but the fundamental tension remains.
How a Foal Is Grafted to a New Mare
Getting a nurse mare to accept a foal she didn’t give birth to requires a careful introduction process called grafting. The goal is to trick the mare’s senses into recognizing the foal as her own, or at least to build enough tolerance that she allows nursing.
According to the University of Illinois College of Veterinary Medicine, the process starts by covering the orphan foal in the mare’s scent. Handlers rub the foal with a towel soaked in the mare’s sweat or drape her halter over the foal. This increases the chance the mare will accept the newcomer. When both animals are ready, the mare is restrained while a handler carefully presents the foal’s nose, ribs, flank, and tail for the mare to sniff and inspect. The introduction is slow and controlled. Some mares accept a new foal within hours; others take days of repeated, supervised contact before they’ll allow nursing without restraint.
Success isn’t guaranteed. Some mares never fully bond with a grafted foal and will kick or bite if left unsupervised. In those cases, handlers may need to restrain the mare for every feeding session until the foal is old enough to wean.
Induced Lactation as an Alternative
Veterinary science now offers another option: inducing lactation in a mare that hasn’t recently given birth. This eliminates the need to breed a nurse mare and produce an unwanted foal. The process uses a combination of hormones that mimic late pregnancy, triggering the mare’s body to begin producing milk.
A protocol developed by equine researchers involves treating a mare with progesterone and estrogen for one to two weeks, combined with a medication that stimulates the hormone prolactin. The shorter version of the protocol takes about a week. Once treatment ends, the mare’s udder is milked to stimulate continued production, and within days she can begin nursing a foal. The medication is continued for several days after the foal is introduced to maintain milk supply during the critical bonding period.
Induced lactation doesn’t work in every mare, and the volume of milk produced can be lower than what a naturally foaling mare delivers. But for operations that want to avoid the ethical costs of the traditional nurse mare system, it’s a meaningful option.
Raising a Foal Without a Mare
When no nurse mare is available and induced lactation isn’t practical, foals can be raised on milk replacer. This is labor-intensive. Newborn foals nurse roughly every 30 minutes in their first days of life, which means someone needs to be feeding them around the clock. Commercial equine milk replacers are formulated to approximate mare’s milk, but the feeding schedule alone makes hand-rearing a serious commitment.
Some veterinary clinics have developed automated feeding devices to solve the scheduling problem. One system, designed by a Texas equine hospital, dispenses small amounts of milk replacer at regular intervals so the foal can feed frequently without the formula spoiling in warm weather. These devices help when a caretaker can’t be present every half hour, but they don’t replace the behavioral development a foal gets from being raised by an adult horse. Hand-raised foals that grow up without equine contact often develop social problems: they may not understand normal horse body language, can become overly attached to humans, or show aggression toward other horses later in life.
The Bigger Picture
The nurse mare industry sits at an uncomfortable intersection of animal welfare and economic reality. Thoroughbred breeding alone produces dozens of orphaned or rejected foals each year, and the need for immediate, reliable milk sources isn’t going away. At the same time, the traditional model of breeding mares solely to produce milk, then discarding their foals, has pushed both rescue organizations and veterinary researchers to develop better alternatives.
Induced lactation protocols continue to be refined, automated feeders are becoming more accessible, and rescue networks for nurse mare foals have expanded significantly over the past two decades. The practice is evolving, but for now, live nurse mares remain the gold standard when a foal loses its mother and needs both nutrition and the social education that only another horse can provide.