How Long is a Horse Pregnant ?

How Long is a Horse Pregnant ?

Regularly, we see on the net people who are worried because their mare, however full, round as a balloon has happily exceeded the 11 months of gestation and does not decide to foal.

What should we think ?

In some cases, the date of the fertilizing mating is not known for sure. It is indeed quite possible when a mare is loose with a stallion, that a return to heat goes unnoticed and that in fact the mare was not impregnated at the cycle where it was thought to be, but only at the following cycle.

In other cases, however, the date of the fertile mating is perfectly clear.

We can therefore calculate the theoretical date of birth by taking 11 months of gestation : mating on 15 May gives birth on 15 April of the following year.

In fact, the average gestation period is 335 days. But depending on the mares, the years and the direction of the wind, the normal duration can vary between 320 and 360 days. So we have an artistic blur of 40 days, which is exceptional compared to other animal species.

In addition, it should be noted that the gestation period influences the length of the gestation period.

A full term mare in July will foal on average 20 days earlier than a full term mare in April, as if she wanted to hurry up so that her foal could grow up before the bad season!

Well, that's not a very scientific remark but you have to admit that it does sound like that !

In short, the length of gestation allows us to predict the time of foaling with the reliability of a 5-day weather forecast, the confidence index is dangerously close to zero.

To know when the foaling will take place, it is therefore necessary to rely on the observation of the mare :

- The elongation of the vulva and relaxation of the ligaments is more or less visible 10 days before foaling.

- The development of the udder between 1 and 4 weeks before foaling is a fairly good criterion. Note that you have a window of several weeks.

- You can follow the evolution of the milk by taking a few millilitres per day at a fixed time and observing its appearance and measuring the calcium level with a test strip.

Transparent and very liquid milk. You can wait for :

Grey milk, a little sticky. It will be soon.

White and viscous milk. Foaling in the next few hours.

Anyway, I already know when the foaling will take place : it's exactly during the 10 minutes when you will have left the stable to go and have a hot coffee !

horse and foal

Gestation and foaling

The gestation period is 11 months, the diagnosis being made by ultrasound on the 14th day. ¾ of mares foal at night and preferably in the summer months. As a general rule, the mare gives birth to one foal but it can happen (this represents less than 20% of mares) that a mare gives birth to two foals. This type of pregnancy, known as "twin gestation", is not without risk. There is no way of predicting the exact moment of foaling.

However, there are a few warning signs : swollen udders, beaded milk, the mare becomes anxious, nervous and seeks isolation.

The mare usually foals standing up, but may do so lying down. Expulsion takes place fairly quickly : 5 to 30 minutes. The birth begins with the loss of amniotic fluid. In a normal foaling, the head and forelegs appear first. This is followed by the neck, body and hind legs. The cord breaks at discharge. If the rupture has not occurred, the mare chews the cord and cuts it. If blood is still flowing, the cord should be squeezed for one minute. It is then soaked in 2% tincture of iodine twice a day for 4 days.

Daily examination of the navel of the foal allows for the early detection of an infection or an abnormality (persistence of the umbilical canal: urine comes out through the navel).

After expulsion, the foal is freed from the envelope that surrounded it in the mother's womb (the amnion) by licking and the airways, which are clogged with fluid, must be cleared by holding the head downwards. Breathing can be stimulated by stimulating the nostrils, pulling on the tongue and rubbing the ribs. This is followed by a recognition session between the mother and the cub via sniffing and licking.

After a maximum of 3 hours, the foal should be able to stand up and suckle. The placenta is normally expelled 3 hours after foaling. If it is not expelled after this time, you should call the vet to have it removed. Do not attempt to remove it yourself, as this may damage the female's reproductive system.

Look for the following signs :

  • If it is lively, alert
  • Its posture
  • Its temperature (around 38°C)
  • If he urinates normally
  • If he is having normal bowel movements (the non expulsion of the first stools, or "meconium", which are the excrements accumulated during the foetal life, can be dangerous for the foal. In the event of a problem, you should call the vet)
  • Its navel
  • Its breathing


  • There are too many people around the stall
  • remove the amnio from the foal (unless the envelope is not torn and the mother does not care for it)
  • help the foal to stand up : let him manage on his own. If, after 2h30/3h, the foal is not standing up and does not head, then you must intervene.


At birth, the foal has no immunity. It will draw its immunity from the mother's first milk (colostrum) during the first 12 hours of life. It is therefore important that the foal can stand up and suckle quickly (if this is not the case, human intervention is essential). Lactation is at its peak in the third month. At this time, the mare gives 4.5 to 6.5 pounds of milk per day and per 220 pounds of weight (a 880 pounds mare will therefore give 17 to 30 pounds of milk per day). Weaning takes place in the 6th month.

Pregnancy in horses : what happens during pregnancy ?

A horse's gestation period lasts eleven months. A pregnant mare's nutritional requirements increase as she approaches foaling. Your horse's diet must be complete and its habits maintained to avoid stress.

The horse's gestation, a delicate natural process

During the eleven months of a horse's gestation period, the foal embryo it carries evolves from about 10 centimetres to more than 1 metre at term, and from 2 pounds at around 4 months to nearly 110 pounds at term. This implies adequate feeding and care to accompany your animal.

The gestation of the horse in stages

Gestation of the horse, the first months

During the first part of the gestation period, the future foal carried by the mare passes from the embryonic stage to the foetal stage. All of the foal's major organs begin to form during this first part of the gestation period : After one month, the cells of the future hooves and eyes are already differentiated, while the foetus is still only one centimetre long and weighs only one gram. From the second month onwards, the placenta is formed and the foetus is properly connected to its mother. Its development can begin in earnest. From forty-five days onwards, sexual differentiation is complete and the genitals of the foetus can be distinguished.

Gestation of the horse, developments between 2 and 6 months

From the second month of the horse's gestation, the foal's growth really begins. It measures between 5 and 7 centimetres and weighs less than 20 g. Its organs grow rapidly. The hooves are formed, as are the external genitalia and eyeballs. Between 4 and 5 months, the foetus weighs about 4.5 pounds and measures 30 centimetres. The umbilical cord is well formed and ensures that the future foal receives proper nutrition and its skeleton begins to form. At 6 months, the foal has doubled in size, is 50 centimetres long and weighs about 11 pounds. The coat and mane begin to appear.

Gestation of the horse, the last months

From the 7th month onwards, the development of the future foal accelerates. Its weight increases from 10 kilos to about 110 pounds and its height increases from 60 centimetres to almost 1.10 metres when the mare gives birth. The internal organs, including the spleen and adrenal glands, are forming, the hair covers the whole body and the mane is well formed. The foal is ready to be born.

Pregnancy of the horse, the care to be given

Throughout the pregnancy period, the mare must be fed correctly so that the foal is not too small when it reaches term. Her diet must be complete, while maintaining her daily intake of forage. This is a period when the mare tends to be stressed, so it is best not to disrupt her habits too much, especially by letting her go out to pasture with her usual companions. About a month before the foal is born, she should be taken to her foaling ground to get used to her new environment.

Pregnant horses, some advice

A pregnant mare needs special daily attention to protect her, especially from insects. Advice should be sought from a veterinarian regarding treatments such as deworming and vaccinations.

By Luisina Giovannini

I created Horse Placenta with the aim of showing all the beauty of this incredible animal which is the horse. I hope you have enjoyed reading this article. I invite you to continue reading to find out more.

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