How long is a mare pregnant?

Mares, which are female horses, have a gestation period of approximately 11 months, or 340 days, on average. However, this can vary slightly depending on several factors such as breed, age, and environment.

Length of gestation

The length of gestation can vary between breeds, with some breeds having longer or shorter gestation periods than others. For example, draft horse breeds, such as Clydesdales or Percherons, tend to have longer gestation periods than light horse breeds, such as Thoroughbreds or Arabians.

The age of the mare can also affect the length of gestation. Older mares, particularly those over the age of 15, may have longer gestation periods than younger mares. This is believed to be due to changes in the mare’s reproductive system with age, which can slow down the development of the fetus.

Environmental factors can also play a role in the length of gestation. Mares that are kept in stressful or unfamiliar environments may have shorter gestation periods than those that are kept in calm and familiar surroundings. Additionally, mares that are undernourished or have other health problems may have shorter gestation periods or may give birth to smaller foals.

It is important to note that while the average gestation period for mares is 11 months, it is not uncommon for mares to give birth anywhere from 320 to 370 days after conception. Mares that are pregnant with multiple foals, such as twins, may also have shorter gestation periods, as the added weight and pressure can trigger labor earlier.

It is essential to monitor the mare closely during pregnancy to ensure that she is healthy and that the foal is developing properly. This includes regular veterinary checkups, proper nutrition, and appropriate exercise. Mares that are experiencing complications during pregnancy, such as placentitis or dystocia, may require additional medical care and may need to give birth earlier than expected.


In conclusion, the gestation period for mares is approximately 11 months, but can vary slightly based on factors such as breed, age, and environment. Close monitoring and proper care during pregnancy are essential to ensure the health of both the mare and the foal.

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