female horse in heat

Recognizing When a Horse Is In Heat

As an equestrian, there are many things you must learn about in order to provide the best quality care for your horse. This is especially true if you own a mare. Whether you plan to breed your mare or not, it’s important to understand how her heat cycle affects her health and behavior.

How can you tell if a horse is in heat? While each horse is unique, there are several signs that a horse is in heat.  Some of the most common signs include tail raising, frequent urination, anxiety, increased interest in stallions, squealing, signs of aggression, unpredictable behavior, and looser bowel movements. You may also find that your mare is difficult to ride or handle while they are in heat.

While some of the behaviors of a mare in heat can certainly be frustrating, there are ways to work with your horse during this time. Planning your riding and training according to your horse’s estrous cycle is one of the best ways to remain productive throughout the month. In this post, we will share everything you need to know about understanding and managing your horse while they are in heat.

Understanding the Heat Cycles of Mares

Understanding the heat cycle of your mare will help you to provide better care for them throughout the year. Horses are seasonally polyoestrous. This simply means that they have a season in which they will cycle followed by a season of no cycling. For mares, the heat cycle is triggered by exposure to light.

As the days begin to lengthen as summer approaches, a mare will begin to cycle. The estrous cycle continues throughout the summer, coming to an end as the days begin to shorten in length. This reproductive cycle typically begins sometime after a mare turns one year old and will continue throughout their lifetime. 

Length of a Horse’s Estrous Cycle

The typically estrous cycle of a mare is around 21 days. During this time, a mare will be in heat for between 5-7 days, followed by about two weeks where they are not in heat. Tracking the cycle of your mare is the best way to predict their behavior and plan for more productive training and riding.

To track your mare’s estrous cycle, simply count roughly 14 days from the day she comes off heat. At the end of the 14 days, it is safe to assume that your mare is once again in heat. 

Signs That Your Horse Is In Heat

clear signs a horse is in heat

Although your horse will display several signs that they are in heat, it can be easy to attribute these odd behaviors to other things. For this reason, it is important to educate yourself on the various ways that your mare may exhibit that they are in heat.

Some of the most common signs that your horse is in heat include:


  • Tail raising
  • Frequent urination
  • Anxiety
  • Increased interest in stallions
  • Squealing
  • Signs of aggression
  • Unpredictable behavior
  • Difficult to ride or handle
  • Irritability
  • Easily distracted
  • Sensitivity to touch
  • Less active than usual
  • Adopting a breeding position


While these are all pretty clear signs that point to your horse being in heat, there is only one way to tell for certain. An ultrasound is the only way to be 100% sure that your horse is in season. If you are planning on breeding your horse, it is best to have a veterinarian perform an ultrasound so that you can begin to accurately track your mare’s estrous cycle.

Behavioral Patterns of Horses in Heat

Your mare’s strongest drive is to reproduce. For this reason, it can be difficult to manage their unpredictable mood swings and frustrating behaviors during their cycle. As you begin to learn your horse’s behavioral patterns while they are in heat, you will be able to establish a better routine that eliminates frustration for both your horse and for you.

Tracking your mare’s cycle is one of the most beneficial things you can do to gain a better understanding of her behavioral patterns. As a general rule of thumb, you can expect your horse to be in a heightened state of irritability for one week, followed by two weeks of normal behavioral patterns. This, of course, will change during the winter months when most mares are not cycling.

Things to Avoid When Your Mare Is In Heat

It is best to avoid certain behaviors and activities while your mare is in heat. Allowing the natural cycle to run its course will ensure that both you and your horse are safe and healthy. Here are a few things to avoid when your mare is in season:


  • Avoid activities that could increase pain or discomfort.
  • Avoid approaching your mare from behind. 
  • Never begin grooming in sensitive areas such as the flanks. 
  • Don’t create a stressful or frustrating environment.
  • Limit strenuous workouts and focus instead on other training.
  • Don’t punish her for irritability caused by pain.


As you begin to learn more about your horse’s unique response to her cycle, you will be able to formulate a plan to make the most of training during this time. At the end of the day, it is important to remember to have patience with your horse. The less than ideal behaviors she is displaying are simply a response to hormonal changes that are outside of her control.

Instead of punishing her for bad behaviors during this time, try to change her focus to other tasks, encouraging the responses you desire. If you find that your mare is incredibly irritable and may cause harm to herself or someone else, you may need to consider some form of pain relief during this time.

Preventing a Horse’s Estrous Cycle

While the estrous cycle is a natural part of the horses’ reproductive system, there are downsides. Unfortunately, in most parts of the world, the natural estrous cycle falls during the summer months. This coincides with many large races, shows, and other important events. If your mare is participating in an event, the unwanted behaviors displayed during the estrous cycle can cause a problem.

For this reason, many horse owners attempt to prevent or delay their mare’s cycle during peak show season. While there are many methods for preventing or delaying the estrous cycle of a horse, the most common method is the use of progesterone

Most often given in an injection, this drug tricks the horse’s system into believing that the mare is already pregnant. In this way, it prevents the display of many of the common signs of heat. It is important to note that although it may eliminate some of the negative reactions, it often makes irritability and anxiety worse. The use of progesterone drugs to prevent heat may also cause infertility that may extend past the use of the drug.

There are other, more natural, methods of preventing or minimizing the negative response your horse has to their cycle. An equine veterinarian can provide you with suggestions that suit the needs of your equine companion.

As you can imagine, there are many opinions and beliefs surrounding this practice. Each horse owner must weigh the pros and cons and determine if it is in their horses’ best interest. By tracking your mare’s estrous cycle and planning your training, riding, and events accordingly, you can successfully navigate the negative responses your mare may exhibit.

Managing a Horse in Season

Trained horse vet with mare in heat

The most important thing to keep in mind while navigating your mare’s estrous cycle is to be reasonable about your expectations. Much, if not all, of the behavioral response to being in heat is outside of their control. To avoid putting unnecessary stress on your horse, realize that there will be a few days each month where she is simply not capable of accomplishing difficult or strenuous tasks. 

Instead, opt for tasks that require her to focus on what she is doing. This will often minimize the negative behaviors she is displaying, at least for a time. Things like groundwork or jumping combinations will allow you to make the most out of your training time while not pushing your horse too hard.

Experiment with various schedules and types of training to find things that your mare responds well to during this time. By establishing a system that works for both you and your horse, you will ensure that you are respecting her needs and providing her with the support she requires.

If you are finding it hard to manage your mare while she is in season, it may be helpful to talk to your veterinarian or a professional trainer. They will be able to look at the situation and point out things that you could attempt. 

The most important aspect of managing your horse while she is in season is to make sure that you are looking out for her health, safety, and happiness. In doing so, you will continue to grow the trusting relationship that you have worked so hard to form. 

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Carmella Abel, Pro Horse Trainer

Hi! I’m Carmella

My husband and I started Equine Helper to share what we’ve learned about owning and caring for horses. I’ve spent my whole life around horses, and I currently own a POA named Tucker. You can learn more here.

Thank you for reading, and happy trails!

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