A horse’s pregnancy is a journey filled with changes and surprises. It’s not just about waiting—it’s about knowing what to expect. 

Each stage brings something new, from tiny movements to big preparations for birth. 

If you own a mare or simply love horses, understanding this process is important. Care, nutrition, and timing all play a role in a healthy pregnancy. 

So, how long does it take before a foal finally arrives? What signs should you watch for along the way? 

Let’s dive into the details and uncover the answers.

How Long Are Horses Pregnant? Key Takeaway

Horses are pregnant for 320 to 370 days, or about 11 months. The exact duration varies based on breed, health, and individual factors. Proper care, nutrition, and vet monitoring can impact the pregnancy length. Mares with good management often have smoother pregnancies and healthier foals.

Signs of Pregnancy in Mares

Recognizing pregnancy in a mare isn’t always easy, especially in the early stages. However, there are key signs that can indicate she is expecting.

1. Lack of heat cycles

• One of the earliest signs is the absence of regular heat cycles.
• A mare that typically shows heat every 21 days but suddenly stops may be pregnant.

2. Behavioral changes

• Some mares become calmer, while others may act more irritable.
• She may reject stallions if they attempt to mount her.

3. Physical changes

• Enlarged abdomen – Visible after several months as the foal grows.
• Udder development – The udder may begin to fill up in late pregnancy.
• Weight gain – Gradual increase, especially noticeable in the later stages.

4. Increased appetite

• A pregnant mare often eats more to support the growing foal.
• Some may experience a brief period of reduced appetite in early pregnancy.

5. Ultrasound confirmation

• A veterinarian can confirm pregnancy as early as 14-16 days with an ultrasound.
• This is the most reliable way to detect pregnancy.

6. Hormonal testing

• Blood or urine tests can confirm pregnancy after 45-100 days.
• Progesterone and Equine Chorionic Gonadotropin (eCG) levels are checked.

7. Fetal movement

• In later months, you may see or feel the foal moving inside the mare’s belly.

8. Changes in energy levels

• Some mares become more sluggish or less active.

How Long is a Horse Pregnant in Months?

A horse’s pregnancy lasts around 11 months or approximately 320 to 370 days, depending on factors like breed, health, and environment. 

The gestation period is divided into three trimesters, each playing a crucial role in the foal’s development. 

During the first trimester (0-3 months), the embryo implants and begins forming major structures. 

The second trimester (4-6 months) brings rapid fetal growth, with the foal developing recognizable features. 

In the third trimester (7-11 months), the foal gains significant weight, and the mare’s body prepares for birth. 

While most mares foal within this timeframe, some may carry longer, especially first-time mothers. 

Proper nutrition, veterinary care, and monitoring throughout these months ensure a healthy pregnancy and successful delivery.

Mare’s Gestation Stages

A mare’s pregnancy lasts around 11 months and is divided into three stages: the first, second, and third trimesters. 

Each stage brings significant changes as the foal develops inside the womb. 

Understanding these stages helps horse owners provide the right care at the right time.

First Trimester (0-3 months)

The first trimester is crucial for establishing a healthy pregnancy. 

In the first few weeks, the fertilized egg travels to the uterus and implants in the uterine wall. 

By day 16, a veterinarian can confirm pregnancy through ultrasound. During this stage, the embryo is very small, and there are few visible changes in the mare. 

However, hormonal shifts may cause mood changes, slight weight gain, or increased appetite. 

Proper nutrition and veterinary checkups are important to ensure the pregnancy remains viable.

Second Trimester (4-6 months)

During the second trimester, the foal begins to grow rapidly. 

By four months, the fetus develops recognizable features, including a head, legs, and tiny hooves. 

The mare may start showing a slight belly enlargement, but she remains active and can continue light exercise. 

At this stage, regular deworming and horse vaccinations are essential to keep both mare and foal healthy. 

Nutritional needs also increase, requiring a well-balanced diet rich in vitamins and minerals. This is a good time to monitor her weight and overall health closely.

Third Trimester (7-11 months)

The third trimester is when the most noticeable physical changes occur. The foal gains significant weight, and the mare’s belly expands visibly. 

By month nine, fetal movements may be seen or felt from the outside. The mare’s udder begins to fill with milk as foaling approaches. 

During the final weeks, she may become restless, spend more time lying down, and show signs of discomfort. 

Providing a safe, quiet environment is essential to prepare for birth. Regular vet visits ensure the foal is positioned correctly and the mare is healthy for delivery. 

Signs That a Mare is Close to Giving Birth

As a mare approaches foaling, her body undergoes noticeable changes. Recognizing these signs helps owners prepare for a safe delivery.

1. Udder development and waxing 

In the final weeks, the mare’s udder fills with milk. A few days before birth, a waxy coating may appear on her teats, known as “waxing up”, indicating that foaling is imminent.

2. Relaxation of the pelvic muscles 

The mare’s hindquarters and tailhead may appear softer or sunken as the pelvic ligaments relax in preparation for birth.

3. Swelling of the vulva 

The mare’s vulva may become swollen and elongated in the final days before foaling.

4. Increased restlessness 

As labor nears, the mare may become anxious, frequently shifting positions, pacing, or rolling.

5. Changes in appetite 

Some mares lose interest in food as foaling approaches, while others may continue eating normally.

6. Frequent urination and tail raising 

She may urinate more often and repeatedly lift her tail as contractions begin.

7. Sweating and increased body temperature 

Some mares sweat around the shoulders and flanks just before labor begins.

8. Dripping milk 

A clear sign of impending birth is milk dripping or streaming from the udder, usually within 12 to 24 hours of foaling.

9. Lying down and getting up frequently 

Mares may lie down and stand up repeatedly, trying to position the foal correctly.

10. Nesting behavior 

A mare may separate herself from other horses, paw at the ground, and become more protective of her space.

Interesting read: Caslick Procedure in Horses.

How to Care for a Pregnant Mare

Caring for a pregnant mare requires attention to her nutrition, health, and overall well-being. 

Proper management throughout the 11-month gestation period helps prevent complications and supports a healthy foal.

1. Provide proper nutrition 

A balanced diet is essential for the mare’s health and the foal’s development. 

During the early months, her regular feed may be sufficient, but as pregnancy progresses, she needs additional nutrients. 

These include protein, vitamins, and minerals like calcium and phosphorus. 

High-quality hay, grain, and supplements recommended by a vet help meet these needs.

2. Regular veterinary checkups 

Routine vet visits are crucial to monitor the mare’s progress. 

An ultrasound can confirm pregnancy early on, and vaccinations, deworming, and dental care should be maintained.

Booster shots, such as tetanus and equine herpesvirus (EHV-1) vaccines, help prevent complications.

3. Provide adequate exercise 

Moderate exercise is beneficial for keeping the mare fit and preventing excessive weight gain. 

Light riding or turnout in a safe pasture is ideal, but as foaling nears, exercise should be reduced.

4. Monitor weight and body condition 

An overweight or underweight mare may face complications during foaling. 

Adjusting her diet as pregnancy progresses ensures she maintains a healthy body condition without becoming too fat or too thin.

5. Ensure a safe and comfortable environment 

The mare should have access to a clean, dry, and spacious stall or pasture. 

As foaling approaches, move her to a quiet and familiar area where she feels safe and secure.

6. Watch for signs of health issues 

Mares can develop pregnancy-related complications such as placentitis (uterine infection) or colic. 

Any unusual behavior, discharge, lack of appetite, or discomfort should be reported to a vet immediately.

7. Prepare for foaling

As the due date nears, have a foaling kit ready with essential supplies like clean towels, a flashlight, iodine for the foal’s navel, and emergency contact numbers. 

Observing signs of impending birth, such as udder filling, waxing, and restlessness, ensures that assistance is available if needed.

Foaling Calculator

A foaling calculator helps estimate a mare’s due date based on her breeding date. 

Since a horse’s pregnancy lasts about 320 to 370 days (around 11 months), you can predict the foaling date by adding this range to the date she was bred.

How to calculate the due date

Find the breeding date – The day the mare was successfully bred.

Add 340 days – This is the average length of a horse’s pregnancy.

Adjust for variations – Some mares foal a bit earlier or later, so expect birth anytime between 320 and 370 days.

Example:

Breeding date: March 1, 2024

Estimated foaling date: February 4, 2025 (adding 340 days)

Possible range: January 15 – March 10, 2025

Complications During a Horse’s Pregnancy

Pregnancy in mares is usually smooth, but complications can occur. Some issues can put both the mare and foal at risk. 

Let’s look into some of the risks:

Placentitis

Placentitis is an infection of the placenta, often caused by bacteria entering through the cervix. It is one of the leading causes of pregnancy loss in mares. 

Symptoms include vaginal discharge, premature udder development, and early milk leakage. 

If untreated, it can lead to abortion or a weak foal at birth. Treatment involves antibiotics, anti-inflammatories, and hormone therapy to help maintain the pregnancy.

Placental insufficiency

Placental insufficiency happens when the placenta does not provide enough oxygen and nutrients to the growing foal. 

This can slow fetal development or lead to pregnancy loss. Causes include poor uterine health, infection, or a twin pregnancy. 

Mares with this condition may not show clear signs, making regular vet checkups essential. 

Treatment focuses on supporting the mare’s health with proper nutrition, medications, and rest.

Systemic infection of the mare

A serious infection in the mare’s body can affect the pregnancy. 

Conditions like equine viral arteritis (EVA), leptospirosis, or septicemia can lead to abortion or a weak foal. 

Symptoms depend on the infection but may include fever, weight loss, lethargy, or discharge. 

If a mare shows signs of illness, a vet should evaluate her immediately. 

Treatment varies but often includes antibiotics, supportive care, and isolation if the disease is contagious.

Metabolic disease

Mares with metabolic diseases, such as Equine Metabolic Syndrome (EMS) or Cushing’s Disease, face a higher risk of pregnancy complications. 

These conditions affect hormonal balance, weight management, and insulin regulation, which can impact fetal development. 

Symptoms may include excessive weight gain, laminitis, or poor coat condition. 

Managing metabolic disease requires a specialized diet, exercise, and medications to keep the mare stable throughout pregnancy.

Can You Ride a Pregnant Horse?

Yes, you can ride a pregnant horse, but with care. 

In the first six months, most mares can handle light riding. They can walk, trot, and even do light cantering. 

Strenuous activities should be avoided. If she was active before pregnancy, she can stay active.

As pregnancy progresses, riding should be reduced. By month seven, the foal is growing fast.

Extra weight can make the mare uncomfortable. Most owners stop riding in the last two months. Light walking is fine, but no hard work.

Always watch for signs of discomfort. If she seems tired or resists, stop. A vet can guide you on what’s best.

Related read: Can You Ride a Horse While Pregnant?

Conclusion

A mare’s pregnancy lasts about 11 months and requires careful monitoring. 

Each stage brings changes that affect her health and the foal’s development. Proper nutrition, exercise, and vet care help ensure a smooth pregnancy. 

Watch for signs of complications like placentitis or infections. As foaling nears, be prepared for labor by knowing the warning signs. 

Some mares give birth earlier or later than expected, so close observation is key. 

With the right care, your mare can have a safe pregnancy and deliver a strong, healthy foal. Stay informed, stay prepared, and give your mare the best care possible.