How long is a horse pregnant before it gives birth? For the average mare, the gestation period is about 340 days. There are 14 days of variance that may occur within that time, so the actual length of pregnancy can be in a range of 326-354 days. Some mares have been known to extend the gestation period for up to 370 days, though there may be an error in the pregnancy documentation in that extended timeframe.
This means the average length of time for a pregnancy with a mare is about 11 months.
Horses that are pregnant can seem to be difficult at times, but if you work on making the process easier on yourself, the 11-month gestation period will go easier for the mare as well. You’ll then be able to set the foundation of care needed for the foal once it arrives.
Here are the steps that can help you be able to properly take care of a pregnant mare effectively.
#1. You’ll want to improve your paddock if necessary.
A pregnant mare will need to have access to shelter, water, and adequate fencing at all times of day. Although the mare can be in the general population of a ranch or farm, it is usually better to keep the mare in the dedicated paddock for the first months of the pregnancy.
#2. There may be feed and exercise changes that need to happen.
The health of the mare will be an integral component to the development of a healthy foal. When mares do not have adequate feed, water, and other various nutrients, then the risk of an aborted pregnancy climbs exponentially. Yet too much feed without enough exercise can also be detrimental to the health of the foal. Overweight mares have a higher risk of giving birth to a foal with angular leg deformities.
#3. Coordination with the local veterinarian needs to happen for vaccination.
A pregnant mare should receive a vaccination at 5 months, 7 months, and 9 months for what is commonly referred to as “rhino.” Rhino is short for rhinovirus, which is a variation of the herpes virus. Not only can it cause flu-like symptoms in horses, but it can also create an upper respiratory disease that can mimic the symptoms of pneumonia. Pregnant mares may also have their foal spontaneously abort due to an infection of this virus.
#4. There are other health issues which require attention as well.
Depending on the location of a pregnant mare, the attending veterinarian may also which to worm the horse about 1 month before foaling. Vaccinations against the West Nile Virus, rabies, and botulism may also be recommended. The goal with the vaccination series is to make sure the foal has the necessary immune cells to fight off a potential infection immediately after birth.
#5. Remember the rules about trickle feeding.
Pregnant mares like to munch on roughage throughout the day. This means there must be adequate feed to allow for the trickle feeding process. It must be available at all times. If there isn’t pasture availability for some reason, then feed hay to reduce the possibility of colic, gut ulcers, and other digestive issues which may try to present themselves.
#6. Pregnant mares can be ridden, but with alterations.
If the pregnant mare is a riding horse, then lightly riding on a regular basis can be good for her health. The riding can take place nearly up until the time she foals. Riding horses have reduced behavioral issues when they are able to get their blood circulation rates up, so lunging, walking, or other physical activities are alternatives to riding if prefer.
#7. Pregnant mares may need assistance with body changes.
Mares who have not foaled before may be unaccustomed to the changes that occur during the pregnancy. By giving her underbelly some extra attention, the mare will be less likely to kick at her foal for being in her boundaries when all it is trying to do is get some food. Mares that receive plenty of attention throughout a pregnancy also tend to reflect that attention to their foal after it is born.
#8. Mares need less space when the foaling date approaches.
About 4 weeks before she foals, a pregnant mare should be moved into a smaller yard. She should still have space where she can get some exercise, either from her owner or on her own, but also has an added level of shelter and protection. Predatory animals are attracted to pregnant mares at this stage, so reinforced fencing is a good idea as well. The goal here is to not irritate the mare in such a way that she feels the need to kick or be aggressive. This could harm the developing foal.
#9. There are physical changes that will take place about 14 days before a mare foals.
When there are about 14 days left in the pregnancy, you can physically see the foal move from a hanging position to one along the mare’s flank. Her udder will begin to increase as well, especially if this is a mare’s first pregnancy. The udder will also become waxy just before birth as the milk comes in. Try to restrict movement so the antibodies in the milk can be passed along to the foal after birth. Otherwise the foal may need more extensive veterinarian care in order to survive.
#10. Most pregnant mares will foal in the early morning.
After the 11 months have passed, a pregnant mare will deliver a foal in the early morning hours, between 1-5am, in most circumstances. Mares tend to get nervous if there are other horses or people present, which can cause them to stop pushing. Don’t be that person with a camera flash that interrupts the process! Once the foal begins to crown, the delivery process only takes about 20 minutes to complete.
#11. Some deliveries do not go as planned.
In a standard foaling, the horse will present with its front hooves in front and the nose resting on top. A veterinarian needs to be present if the foal presents in any other way to preserve the life of the mare and the foal. If the birthing process takes longer than 20 minutes, then a veterinarian should be present as well.
#12. The mare must pass along the entire placental membrane.
If any part of the placental membrane remains with the mare after the foaling is complete, then the risks of a severe infection, including blood poisoning, are quite high. This issue presents itself as a rapid fever, with colic symptoms, that may extend for several days.
#13. The foal will begin to try moving almost immediately after birth.
It only takes a couple of hours for a foal to try to make it to its feet. This is the same amount of time it should take for the foal to begin the nursing process. The mare and foal should be kept under regular supervision during this time to make sure their health is ensured. Those observing the horses during this time should also look for the meconium, or tar-like black manure, which is what the foal will pass after birth. Sometimes it can be retained, which can lead to health issues and colic symptoms. A veterinarian may need to give the foal an enema in order to initiate the bowel movement.
#14. A foal should also be able to drink and urinate.
This doesn’t always happen right away. Some foals need about 24 hours to begin the normal body processes. If this doesn’t happen by the end of the first full day for the foal, then a veterinarian should be consulted to see if there is a health issue which needs to be addressed.
#15. The mare and her foal can be moved back to the larger paddock after 72 hours.
This is under the assumption that the foal and mare are completely healthy. You’ll want to move them to the larger yard so they can get some exercise. The smaller yard will still be adequate if the development process is not occurring as you or your veterinarian would like.
#16. Foal movement restriction might also be necessary.
Leg issues with foals can be quite common. This includes tendon development which causes the foal to walk on its heels or fetlocks. As the foal grows stronger, the issue will resolve on its own, but some movement restriction may be necessary. Foals that walk on their toes could require splinting to prevent ligament or tendon damage that may affect how they walk for the rest of their lives.
Horses may be pregnant for 11 months to bring a foal to full-term, but that doesn’t mean the mare will want to be inactive during that period of time By following these steps, any horse owner can help to provide their mare with the care it needs so that the foaling process can go as smoothly as possible.