When a mare becomes pregnant, owners should discuss their mare's individual nutritional and exercise needs with their veterinarian. Typically, the first four months of a mare's pregnancy are not that demanding. At five, seven, and nine months of pregnancy, it is recommended mares in the US should receive a rhinopneumonitis (Equine Herpes virus) vaccine to help prevent abortion.
At 30 days before giving birth, veterinarians recommend that mares in North America receive a standard five-way vaccine for rhinopneumonitis, influenza, tetanus, Eastern encephalomyelitis, and Western encephalomyelitis, as well as a West Nile virus vaccination. This ensures the mare has a good colostral antibody concentration when the foal is born. Additionally, the mare should be dewormed at this time.
Owners should also watch for any dental, digestive, or parasitic problems. During the last trimester, a mare's nutritional intake should increase by about 20 percent.
Owners should make sure she is actually eating all she is given and that she is eating quality feed that provides adequate essential vitamins and minerals. A vitamin/mineral supplement is generally necessary to meet all of her needs, and she may require pellet feed as well as hay.
A mare's gestation length ranges from 335 to 340 days, so an owner can calculate the date they think the foal is due by determining the breeding date and adding 340 days. About two to three weeks prior to parturition or foaling, mares should "bag up" - have obvious mammary development. If this happens earlier, there could be a problem with the pregnancy and a veterinarian should be called to check it out.
"A common cause of abortion is placentitis, or inflammation of the placenta," said Dr Ahmed Tibary, a large animal theriogenologist (reproduction specialist) and professor at Washington State University.
"We can diagnose this condition during episodes of premature lactation or 'bagging,' and there are some good treatments available to save these pregnancies.
"Suspicion should also arise anytime during pregnancy when a mare begins to display signs of colic. Even with mild cases, a veterinarian should be called immediately. The earlier a problem is detected and resolved, the better the prognosis is for the foal and mare.
Most mares foal in darkness, so foaling monitors and cameras can save many sleepless nights for owners.
There are several important ways for owners to be involved in the birth process and several things they should avoid.
"Eighty-six percent of foals are born between 7pm and 7am. so foaling is usually a night-time event," said Dr. Siddra Hines, a WSU equine medicine resident. "The most common birth time for horses is between 10pm and 11pm."
Some owners attach alarms to their mare's halter, or install cameras in the foaling area or stall so they can keep a watchful eye and make sure they don't miss out on the birth.
"The first stage or initial sign of foaling can resemble signs of mild colic, but shouldn't last longer than four hours before the foal starts to come out," Dr Hines said.
"Once stage two begins, the foal should be born and on the ground in about 15 to 20 minutes. If it takes longer than that, the foal is probably stuck, which is a serious medical emergency that is life-threatening to the mare and foal. The veterinarian needs to be called immediately if the owner has any suspicion that the mare is having trouble giving birth.
Once the second stage of foaling begins, the foal should be born and on the ground in about 15-20 minutes.
"The third stage is the passing of the placenta, which should occur within three hours after birth," she said.
"Whoever is there attending the birth should not try to pull the placenta out because it could tear, impairing the ability of the placenta to pass on its own. When the placenta does come out, it should be saved for the veterinarian to look over to make sure the entire placenta is there and normal. Any portion left behind constitutes another medical emergency because it can cause the mare to develop a uterine infection and endotoxemia, which can become life-threatening.
"Even if an owner happens to miss the birth, the placenta should be able to be found on the ground and saved for the veterinarian. Generally veterinarians perform a physical exam on the mare and foal about 18-24 hours after birth. If the owner suspects any problems or that the mare has a retained placenta, a veterinarian should be called as soon as possible to treat any infections that can quickly develop.
"Immediately after the foal is born, some people may think they should cut the umbilical cord, but it is important to let it tear naturally," Dr Hines said.
"If it is cut, uncontrolled bleeding can occur, but if it tears by itself, there is minimal bleeding that will stop on its own.
"To help prevent infection, owners can dip the foal's umbilicus or navel in a disinfectant solution within the first hour after birth and several more times within the first 48 hours. One good disinfectant is a 0.5 percent chlorhexidine solution. A strong solution of betadine or iodine should not be used because tissue damage may result, which can predispose the area to infection.
An owner or veterinarian can also take the foal's vital signs, make sure it is getting enough colostrum or first milk, and that it is standing, nursing, and displaying normal behavior. "Foals should roll upright in about five minutes, have a suckle reflex within five to ten minutes and actually suckle within about two hours after they are standing," Dr Hines said.
"They should also stand within 30 minutes to an hour, and pass meconium (or the first faeces) within 12 hours after birth. Generally, neonatal foals nurse multiple times per hour, and consume almost a quarter of their body weight a day in milk. They should be bright and inquisitive, but should also try to run away and hide behind their mother when a person comes into their stall."
The foal should ingest 2-3 litres of good quality colostrum within the first six hours after birth.
A mare postpartum should be bonding with her foal, eating and drinking, and not acting overtly painful or colicky. An owner or veterinarian should check her vital signs, that her mammary glands are clean, and that she is producing enough milk. The foal should ingest 2-3 litres of good quality colostrum within the first six hours after birth. If this does not occur, the foal will suffer from "failure of passive transfer," or FPT, which is a lack of antibodies in the blood important for protecting the foal against many types of infection.
"A veterinarian should come out within 18-24 hours after birth to examine the foal and do a blood test to ensure that the foal received adequate colostrum," Dr Hines said.
"A veterinarian can administer plasma if the foal has failure of passive transfer. Some people think that powdered colostrum from a store can suffice, but it won't provide the antibodies that a foal needs. Plasma is the only product that can effectively treat failure of passive transfer and it is administered intravenously by the veterinarian.
"Have the veterinarian come out earlier, however, if there are any problems, such as if the foal isn't nursing, standing, or is not behaving normally," she said.
"Things can go wrong very quickly with foals, so it is best to get veterinary help as soon as any problems arise.
"Owners can be involved in the postpartum process, but need to be careful not to get between the mare and foal," Dr Hines said.
It is essential to provide the mare with exercise and access to a paddock after the birth.
"Mare behavior can change dramatically after foaling, even if she was the nicest mare in the world. They can naturally get aggressive to protect the foal and might hurt a person, herself, or the foal trying to protect it.
"It is also important to remember not to lift a foal with your arms under its abdomen if you think it needs help," she said. "This can cause a ruptured bladder, which can be apparent if you see the foal posturing to urinate and it can't. Eventually the abdomen will become distended. Foals should urinate every time they get up to nurse."
If the mare and foal are doing well the first day or so postpartum, it is essential to provide the mare with exercise and access to a paddock to help her uterus shrink and eliminate fluids. Her nutrient requirements increase even more while she is lactating, so she should also be fed quality feed and supplements to provide adequate nutrition for her and the foal.
Broodmares can come back into heat within a couple of weeks postpartum. If an owner of a broodmare that has just given birth is planning to rebreed her, a veterinarian should perform a pre-breeding soundness exam to ensure she is ready to conceive again.