Pregnant mares.

Once the mare's pregnancy is confirmed, three hundred and forty-five days, plus or minus 25, is approximately the length of time that the mare will be pregnant.

Pregnant mares are somewhat unique in that although their gestation period lasts most of a year (11 months), it is only in the last three months of pregnancy that they should actually be treated as "pregnant mares."

The foal really begins a significant growth spurt in the last three months or so, in the last trimester. Until eight months, it's almost like a regular horse. Of course, there are always exceptions to this rule: mares with complicated pregnancies, such as repeated abortions, older mares, or those with specific health problems. It's certainly important to avoid stressing the mare as much as possible.

The first 30 days are truly critical; the embryo must be well attached, and the mare should not be doing any strenuous exercise, especially in the hot summer, until the pregnancy is more or less established. During this first month of pregnancy, she should only do light work as a special precaution. During these first 30 days, there is a 10 to 15 percent chance that the embryo will be reabsorbed. Stress, illness, uterine infection, hormonal abnormalities, the presence of twins, and other factors have been implicated in early embryo loss. Often, the cause remains undetermined.

Once this first month is over and the mare is happily pregnant, moderate exercise, such as brisk walking or riding, will help control her weight and maintain the muscle tone and strength needed for the last two months of pregnancy. When riding, there's no need to limit yourself to a gentle trot/walk session. Until approximately eight months of pregnancy, you can continue with normal training and even compete.

You might be tempted to pamper your pregnant mare by keeping her in a clean, warm stall with soft, fresh bedding at all times. Keep in mind, however, that horses don't exactly view life in the stall as a luxury. What they'll want and need is fresh air, movement, and grazing time with compatible pasture companions.

We must avoid any undue risk of injury or disease transmission by isolating broodmares from transient horse populations. We also don't have to worry too much about low temperatures during pregnancy, because horses are very resistant to cold. Just keep them dry and out of the wind; an open field with an artificial shelter or a forest is ideal.

To maintain her body condition, we feed the mare free-range pasture grass and high-quality forage, just as we did before pregnancy. This will provide a constant source of energy and keep her gastrointestinal tract functioning optimally, with an increase in energy as required by the progress of the pregnancy. In cold climates, we take into account the additional requirements needed to maintain body condition and adjust her ration accordingly.

Mares that are too thin at foaling will produce little milk and may also have a longer gestation period or give birth to underdeveloped foals. Mares that are too fat are prone to developing laminitis or difficulty giving birth, and may even produce lower-quality colostrum.

We have already mentioned that during the first seven or eight months of gestation, the fetus grows very slowly, so early pregnancy does not represent a major nutritional challenge for the mare. However, during the last three or four months of pregnancy, the unborn foal begins to grow and develop more rapidly.

During the last 90 days of pregnancy, the fetus gains almost 75% of its weight. This has a significant impact on the mare's nutritional requirements for protein, vitamins, and minerals. Winter, with its sometimes extreme weather, poses some nutritional challenges for pregnant mares because this is the transition period from mid- to late gestation.

The increased size of the fetus also takes up more space in the mare's body cavity, causing the mare to eat less hay or forage. This reduction in forage consumption, coupled with the increased nutritional demands of pregnancy, leads to the need for mares to supplement with a nutritionally balanced concentrated grain mix to meet total nutrient requirements. Even in situations where forage alone normally maintains mares in acceptable body condition, it is important that they receive quality concentrated supplements.

Mares that do not gain weight during the last trimester will use their own body energy reserves to support fetal growth. This puts the mare at a disadvantage after foaling, when she will need those body energy reserves for milk production. Proper nutritional management of the broodmare during late pregnancy will give her foal the best start in life.

In short, mares should be fed as many nutrients as possible in the form of good-quality hay and grass, and starting in the last trimester, supplemental grain should be provided as needed to maintain physical condition. We should also provide quality protein to ensure adequate intake of essential amino acids and supplements of copper, zinc, and vitamins. There are many commercial feeds for pregnant mares with quality minerals and protein, with those with a lower protein level ideal for mares receiving a little alfalfa, and products with 30% protein for mares consuming grass hay.

As with all animals, they should always have plenty of clean, fresh (not frozen) water . Keep in mind that pregnant mares require about 10 percent more water than non-pregnant mares.

And also, like all horses, free access to a salt block or loose salt.

Vaccinations should be administered before the mare is mated, avoiding vaccinations during the first few days of gestation. In general, vaccinations should be avoided until 30 days before foaling.

The stakes are high when a mare is pregnant. Talk to your veterinarian early on about a vaccination plan for your broodmare. Core vaccines have clearly demonstrated efficacy, safety, and a high level of benefit and low level of risk to justify their use in all horses.

Keeping the mare free of parasites is also essential for her health and well-being, and although most currently available antiparasitic agents are relatively safe for pregnant mares, we should avoid deworming from the last four weeks of pregnancy, as this could cause abortion.

Routine deworming of pregnant mares during pregnancy will reduce the newborn foal's exposure to parasites. Therefore, mares should be dewormed regularly, according to the schedule established by your veterinarian for your particular climate, with the final treatment given approximately 6 weeks before the foaling date.

Podiatry is important, and mares' hooves should not be neglected during pregnancy, even if they are not ridden. While pregnant mares generally don't have any special hoof needs, they will still require regular trimming.

As broodmares reach the final months of pregnancy, their weight increases, placing a heavy extra load on their hooves.

This stage of gestation also often coincides with late winter, when the base of the pasture is likely to be deep and muddy or hard and rough as the mud dries. Furthermore, allowing the hooves to become too long and overly large changes the angles of the tendons and bones, increasing stress. During labor, she could accidentally injure herself or the foal if her hooves are excessively long and uneven.

Dentistry is a commonly neglected area in broodmares. Regular dentistry is just as important, if not more so, for broodmares compared to any other horse, as they are expected to grow and produce a healthy foal.

At the end of pregnancy, the developing foal takes up a lot of space in the mare's abdomen, which means the mare's teeth and digestive system must be as efficient as possible to maintain weight and grow a healthy foal.

A general recommendation is that annual dental exams and procedures be performed before the mare is mated or after the mare gives birth to avoid the stress of the procedures, possible complications from infections, and sedation during pregnancy.

It is advisable to introduce the mare to the foaling environment 4–6 weeks before foaling to minimize stress around the time of foaling and allow her to acclimate. This will also expose the mare to any pathogens present in this new environment and give her time to develop antibodies. These antibodies will be transmitted to the newborn through colostrum and provide protection for the foal.

In the later stages of pregnancy, she may begin to appear irritable or restless, often coinciding with the foal's activity. During these times, if you closely observe the mare's flank area, you will often see the foal moving.

As mares approach foaling, a patch of swelling (edema) often develops from the udder forward along the underside of the belly. This results from the mare's circulatory system being interfered with by the heavy weight of the pregnancy, but it does not indicate a problem and resolves quickly after the mare foals. Often, the mare's hind legs also swell with the additional weight, but this, too, usually resolves quickly after foaling.

The appearance of the udder is important for estimating calving . A few weeks before she gives birth, her udders will fill with milk, which is usually noticeable. They usually begin to enlarge between 4 and 6 weeks before calving and gradually increase in size as calving approaches.

The color and character of the milk is a good indicator of the time until calving. Up to one or two days before calving, udder secretions are usually clear to honey-colored. A few drops can be milked onto your hand for examination. Typically, within the last 24 to 48 hours, the milk turns grayish and then white.

A tan waxy substance is often seen forming on the tips of the teats. It is true that most normal mares give birth within 24–48 hours of this wax forming. However, many mares never form wax, so it is not a reliable means of predicting foaling.

Another sign of impending labor is the softening of the ligaments around the head of the tail and the enlargement and swelling of the vulva. On the last day, we will also notice how the mare prefers to remain alone and separate from the herd.

Ultimately, the best way to predict foaling is to combine all of the above factors with experience. Even then, predicting when a mare will foal can be tricky. Most pregnancies and births are uncomplicated and require little human assistance, but isolated incidents do occur.

Finally, remember that throughout pregnancy, broodmares should be examined daily for any signs of lethargy, reduced appetite, vaginal discharge, and/or premature udder development, as these can be signs of infection and/or abortion. If any of these symptoms are observed, contact your veterinarian as soon as possible.