When Do Horses Go Into Heat & What Age Do They Stop Cycling?

Last Updated on February 22, 2022 by Allison Price

We chose to replace an old broodmare by a young prospect. We need to know when our new horse will enter heat and be old enough for breeding, and how long will our older mare continue to cycle.

Horses usually have their first heat cycle at two years of age and then stop cycling at twenty-years. The average horse’s estrus cycle is three weeks long and can be affected by factors such as age, location and the time of year. Horses are unique and may have a different cycle from those set by the standards.

Horse owners are often unaware of mare heat cycles. If you want to breed horses, you will need to be familiar with horses’ estrus cycles.

When Do Horses Go Into Heat & What Age Do They Stop Cycling

Horses experience heat cycles

It can be hard to manage a mare in heat, especially if they have stallion companions. You can recognize signs the mare is feeling this way and help you manage this natural cycle.

First heat for fillies

A filly is most likely to become heat in her first year. It depends on many factors, including the season. Horses don’t usually go into breeding season during winter months, unlike humans. Their breeding season usually begins in April.

The filly’s proximity to other horses, especially mares in or about to enter heat, is another factor. Another reason for heat earlier than usual is stallions. However, a season can cause a filly to enter a first heat later.

Estrus cycle length

The estrus cycle lasts three weeks for mares. They can stay in heat for as short as 2 days, or as long as 10 days. They will remain in heat until the days start to get shorter, which is usually around September.

This cycle can vary depending on where you live. The cycling time will be shorter in the northerly hemisphere, and shorter in the southerly hemisphere. It may take longer in the middle of the globe.

Why breeders should care about the length of heat cycles

Because of the way birthdays are listed in horse registries, it is important to know your mares’ breeding cycles. The eleven-month gestation period for mares is 11 months. All foals born in the Northern Hemisphere on January 1st of each year are considered to be born.

Your foal will be considered one-year old if it is born on January 1, 2021 if it was born in May 2020. Your mare should have her foal as soon as possible. Understanding a mare’s estrus cycle is crucial to ensure that your foal is born in the right time.

A few months can make all the difference in horse racing. Most tracks offer races for two-year olds during the fall season. Horses born later in the year could be matched with horses six to seven months older, or they may miss their entire two years-old season.

In many other disciplines, horses are judged by their age. For example, barrel racing futurities, dressage, jumping and dressage.

How to deal with mares during heat.

For those who are new to horse ownership, mares in heat can pose a problem. They can do a variety of things, some more than others. Most are easy to manage once you understand why they do it.

Mares that are in heat may urinate more frequently and stand differently. You may be able to see their vulva “winking” and they will lift their tails higher. As mentioned, this can get worse if there are stallions nearby. You may also exhibit other sexual behaviors.

Here are some things you should know.

Here are some things you should know about handling mares. The first is to never approach the mare from behind. It is not wise to approach a mare in heat from behind, even though it is common in all situations. Begin grooming at the neck and head, not the flanks. They will be more sensitive now.

In heat, mares may feel pain similar to what women feel during menstruation. The vet might suggest that you give the mare pain relief if this happens. Some are gentle enough for horses, and some are made specifically for horses.

What happens when a mare stops having heat cycles?

The final question is “When does a mare stop experiencing heat cycles?” The exact time will vary, just like older women. The age that is officially given is generally around twenty-five. Horses can live up 30 years so it’s not like menopause.

This will again depend on the individual. Some people may quit at age eighteen while others may continue to work later. Some horses may be older than others, sometimes even reaching twenty-two years. As a result, chances of a mare becoming pregnant from heat are less.

Talk to your vet and previous owners if you’re new to horse ownership. These people can help you understand what to expect and how best to handle it. If you want to avoid heat, the vet can discuss options and help you decide the best way to deal with the situation.

Is it possible to stop horses from getting into heat?

Why would anyone want to disrupt the mare’s cycle? There are many reasons to do this, just like there are for human females. It can be difficult to show a mare in heat, as we have discussed. There will be many horses, and some might be stallions.

It could also be dangerous for a mare to exhibit heat symptoms while trying to show. Horse and rider are both at risk. Some mares may not pay as much attention or be as circumspect as they should.

It could also be disastrous if the mare is being ridden by someone unfamiliar with horses. It is important to take care when a mare is in heat. However, not all horses have these issues.

There are several ways to avoid your mare going into heat. Some of these methods may not work, and others could cause problems for the mare’s reproductive health in the future. These are important if the mare is going for show work.


medication is the best option, since they are more reliable and easy to use. Two drugs can be used. The first is a longer-term birth control medication. One must be used throughout the entire time the mare is in heat.

This is usually used to show mares, which the owner might not want to breed. Regumate can temporarily make a mare infertile. It doesn’t stop once the drug has been stopped. It will take some time for it to wear off.

Oxytocin can also be used. This hormone is known to most women who have had children. The mare’s uterus may be fooled by the correct dosage to think it is already pregnant.

Marble trick

This trick works approximately forty percent of all the time. Just as heat is ending, a sterile marble can be inserted into the mare’s cervix. Sometimes, the mare may “slip” the marble. It will look like a miscarriage.

It works for about three months if it is working. The mare can be bred easily once it is removed. If the mare is left unattended, it can cause serious problems including infertility. It is often due to infections.

Allison Price
Allison Price

I’m Allison, born and raised in San Diego California, the earliest memory I have with horses was at my grandfather’s farm. I used to sit at the stable as a kid and hang out with my Papa while he was training the horses. When I was invited to watch a horse riding competition, I got so fascinated with riding!