The COMPLETE Breeding Behavior Of Horses

As a horse owner or breeder, it’s quite important to understand the behavioral changes of a horse under the estrous cycle or during the mating process.

So, what is the breeding behavior or horses? When mares are in heat, they’re more receptive to the male stallions. The mare undergoes several behavioral changes like restlessness, hyperactivity, and frequent urination. Stallions exhibit similar behavior where they’re overly hyperactive and stay closer to the mare. Once satisfied, the two indulge in copulation. 

Next, let’s go over the mating behavior of mares, stallions, and geldings, with a quick discussion of the estrous cycle in mares as well.

Breeding Behavior of Horses in the Wild

Horses behave differently in their natural conditions as compared to the breeding farms. In the wild, horses live in herds where a dominant Stallion breeds the mares. The younger fillies and stallions are forced to make new bands.

In the breeding farmhouses, horses are paired and so we don’t get to see the stallions competing for the mares. Still, horses living together exhibit dominance and the caretaker of the farm will clearly know the boss stallion.

The Breeding Behavior of a Stallion

The classic breeding behavior is the flehmen response. This response refers to when a stallion lifts its nose into the air and curls his upper lip in a goofy smile, responding to a mare in heat.

During the breeding season, the stallions are often impatient, hyperactive and aggressive.  

They will tease the mares to check for the signs of readiness to mate while vocalization is also normal. The stallions will often bump into the mares, they will nudge them, smell or bite the mare’s body to make sure she’s ready to mate.

The Breeding Behavior of mares

During the breeding season, mares would cycle many times until they conceive. During the heat or estrus the mare is most receptive to the stallion because of ovulation and so show intense sexual behaviours.

The classic breeding behaviour of a mare in heat would be frequent urination, squatting or straddling posture, raising the tail and flashing the clitoris. Some mares would lay against the fence in the presence of a stallion to signal readiness.

The Breeding Behaviour of Geldings

Although castrated, some geldings still show stallion-like behaviours around mares. This is more common in horses that were gelded later in life. If given a chance, geldings show the classic breeding behavior referred to above as the Flehmen response to mares in heat and would try to mount the mare too.

Modern Horse Breeding 

Breeding in horses occurs mostly in controlled environments nowadays. The breeders will select and pair the perfect mare and stallion, however, artificial insemination is also common.

In the wild, stallions compete for the mares and only the most dominant one gets to breed the mares of the herd.

Puberty in Horses

Puberty is the time when colts and fillies start maturing sexually. Fillies can show signs of puberty at as young as 9 to 10 months of age, while most reach puberty at 12 to 15 months. Stallions hit puberty around 15 months and older.

Even though young fillies show readiness for mating, but their sexual tracts are not yet fully developed, and they cannot get pregnant.

Horses can breed and get pregnant by the age of 2. But It is best to breed a mare when she reaches the age of 3 or 4, while the same can be said for stallions.

The Estrus Cycle in Mares

The time when a mare is ovulating is called Estrus or heat. It is the period in which a mare is more likely to conceive if she mates. Mares go through multiple estrous cycles during springs and summers, the natural mating season of horses in the northern hemisphere.

Each cycle is roughly 21 days long, but it could be longer or shorter for different mares. After every estrous cycle, a mare enters the estrus or heat which typically lasts for 2 to 10 days. The cycle may repeat 3 to 4 times in a season until a mare gets pregnant.

Horses breed in the long summer days and though some mares cycle through winters too, most mares tend to be anestrous during winters.

What’s Foal Heat?

The first heat or estrus period that mares experience after giving birth is called foal heat. This heat period occurs generally after 6 to 9 days of foaling. It could start as early as five days after the birth or as late as 15 days after foaling.

Artificial Estrus Triggers

Estrus naturally happens in the spring and summer months, but breeders sometimes use artificial triggers to stimulate estrus in the short day-light days.

Sometimes breeders will keep the mare under artificial light in the barn to stimulate estrus to control the time of the year they will foal. 

Horse Courtship Behavior

It’s important to recognize the behavioral signs of mares in estrus, and how the stallions are responding to them. Some general signs are restlessness, hyperactivity, and aggressiveness. During this time, horses will be running around more than usual and will seem to have lost interest in eating or resting.

Some distinct behaviours are also displayed by stallions and mares in heat. The mares will frequently urinate, squat in the presence of the stallions and flash their vagina. While the stallions along with being aggressive, hyper, and restless will raise their nose and fold the upper lip backward when they see a mare.

Why do Horses Fall After Mating?

Some horses collapse after mating for the first time, and there are horses that fall every single time they breed. This is an interesting behavior, and vets don’t have much explanation about the phenomenon.

One scientific explanation could be that stress, excitement, and hormones make the animal a bundle of nerves and so to control its elevated heart rate, a horse lays down till its breathing and heart rate becomes normal. This can happen with dogs too when they mate for the first time.

This could also be because of an underlying medical condition or syncope.

Syncope in Horses

Syncope is a condition when a horse faints if the blood flow to the brain is insufficient, due to low arterial blood pressure. This is most likely a glitch in the cardiovascular system. And may lead to cardiac arrest.

Some stallions that are gelded late develop this problem as well, which might be related to their heart most of the times. Similarly, fainting after mating with a mare is also attributed to heart problems. It is interesting to know that having heart attacks while having sex is not uncommon in horses. 


Another reason for frequent fainting in horse could be sleep deprivation or an uncurable neurological sleep disorder known as narcolepsy. During this condition, the animals suffer sleep attacks, but this mostly happens when the horses are resting or are inactive for some time.


Horses breed seasonally, therefore, their breeding behavior can be observed during the long daylight months of spring and summers. Mares go through cycles of heat called estrus cycles and present themselves to the stallions. They copulate a few times until the mare conceives.

Normally in a wild setting, the dominant horse will breed all the mares in heat, while in a farm setup, mares and stallions are paired so there’s no competition between stallions.

Related Questions

How many times can a horse mate in a day?

At a farm, stallions can get an erection up to 18 times a day and can mate more than 2 to 3 times. However, in the wild, a stallion can mate much more than that. Though the number of sperms will go down per breeding when many mares are in the heat on a given day.

Do horses mate for life?

In the wild, the most dominant horse breeds all the mares in heat. When the mares and fillies are in estrus, they try to attract the stallions in the herd. In the wild, the horses form a harem and then form strong bonds. But they are not monogamous and may change their mates. However, in the feral condition’s, they usually do not mate with closely related horses.

How long do horses mate for?

Horses are long-day breeders; they mate only in the long days of summers and springs. The mares go through seasonal estrous cycles of 21 days followed by 3 to 7 days of estrus or heat. This mating behavior is a natural adaptation so the foals will be born in months when survival is easier.


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