Managing Heat Cycles in Mares

This article teaches owners the signs and behaviors of a cycling mare. For optimal horse health and breeding success and owner safety, a horse owner needs to recognize when a mare is in heat.

For horse owners with mares, heat cycles in mares is an entirely different element of equine management. Regardless of whether you plan to breed your mare, her heat cycles will affect her–and subsequently you. In order to better understand and care for your mare, you need to understand her heat cycles. The last thing a horse owner wants is for heat cycles to interfere with riding and training and horse safety. Horse health care is extremely vital with a cycling mare, so these horse tips from the horse experts will help you and your mare stay healthy, safe and productive.

Reproduction is the most basic, strongest drive your horse has – even to the point of taking precedence over eating. Small wonder then that your mare’s reproductive cycles may produce pretty obvious signs, and her attention when in season (“heat”) is not primarily focused on you. Understanding what’s going on, and the timing, can help you deal with it more effectively.

Mares typically cycle regularly between April and early September. For a few months on either side of that, the ovaries are in the process of either gearing up for spring or slowing down for winter and may produce one or multiple follicles at irregular times. During these spring and fall transition periods, the mare may or may not show signs of being in season. Reproductive behavior is most likely to be noticed during the fertile period between April and September.

A mare’s cycle is shorter than a woman’s. The average length is three weeks, with most falling within the range of 18- to 23-day cycles. The mare will be in season (“show heat”) for an average of five days during each cycle, with a range of three to seven or eight days. Many people complain that their mare is in season every two weeks and think that’s abnormal, but it’s not. The normal cycle is for the mare to be in season for the better part of a week, followed by two weeks out, then another week or so in.

When a Mare’s in Heat

· Avoid approaching the mare from behind.
· Begin grooming at the neck and shoulders before working back to the sensitive flanks.
· Ovulation can produce pain, so give the mare some Banamine if her
irritability is extreme.
· Try to interrupt the heat-cycle symptoms only during work or riding sessions. Don’t pick at her.
· Consider focus-type lessons, such as ground poles and changes of speed and direction.

Typical signs that the mare is in season include holding the tail elevated, “winking” (opening and closing) the lips of the vulva and variable amounts of squatting and squirting of urine and mucus. A mare’s level of activity usually slows down a bit, and she often seems preoccupied. It’s more difficult to get and hold her attention, because frankly you’re not the most important thing on her mind at the time. These are the signs of being in full-blown “heat,” which will intensify gradually over a few days, then stop abruptly after she ovulates.

Just before coming into season, and often for the first few days they are showing signs, some mares are very irritable and sensitive to touch. They may threaten to kick or even bite. Part of this is because the hormonal changes are making her focus elsewhere so that she is more easily startled. Pressure-like pain from the enlarging follicle and/or pulsations in the ducts that will carry the egg to the uterus are also likely involved.

What Should You Do?
The first thing to understand is that you don’t really have to “do” anything about your mare’s seasonal behavior. It’s a perfectly natural thing.

If your mare shows irritability and touchiness just before going into season, or while in season, understand first that it’s because she’s preoccupied and also may be uncomfortable. Don’t punish her for this; try to work with her.

Never approach her from behind during these times, unless you’re sure she has noticed you are there. Start grooming her at the neck and shoulder, working your way back to the more sensitive flank regions.

If the irritability is extreme and could be dangerous to people working with her, the first thing you can try is giving her Banamine for pain relief. A day or two of Banamine can make a world of difference. If that doesn’t work, ask your vet to examine her to make sure her ovaries are normal and to suggest any further treatment to help her.

If you have problems with the mare being easily distracted, disinterested in work and even showing signs like elevating her tail and urinating when being ridden, you may be able to minimize this by focusing only on trying to interrupt the behavior when she is being worked. Too many people try to get the mare to stop showing estrus at all times when they are around her – when grooming her, walking her, turning her out.

You must have her attention at all times to be safe, but don’t expect her to completely shut down her strong hormonal drives just because you’d like her to. Avoid picking at her , but send a strong message when you’re in the saddle or actively leading her to tell her “OK, it’s work time.” Concentrate on telling her what you want her to do, and avoid scolding her for behavior you don’t want.

Boys vs. Girls

Although stallions undergo seasonal cycles with regard to how fertile they are too, there are differences. Stallions are “on” virtually all the time, ready and able to breed whenever there is a receptive mare. Ironically, though, they are much easier to shut “off.”

Properly managed stallions do not exhibit sexual behavior unless there is a receptive mare around and will never attempt to breed a mare that is not in season. They may tentatively test the waters, but if the mare indicates she’s not interested, they back right off. This “off switch” actually makes stallions more easily trainable with regard to expressing sexual behavior. Though mares are totally “off” part of the time, they are almost irresistibly “on” when their hormones are dictating to them.

Be reasonable about your expectations, too. For the few days when the mare is strongly in season, don’t expect her to work successfully on difficult tasks or easily learn something new. This is a good time, though, to work with exercises that force her to stay focused, such as ground poles, jumping combinations and frequent changes of gait or direction.

You’ll have to experiment to find the right combination of tasks that will keep your mare working with you without putting her into overload. Some mares may do best on long, relaxed trail rides alone or with a best buddy during these days.

If you’re not successful in working with the mare on your own, get the advice of a professional trainer. If this doesn’t work and you still have significant problems with the mare being too irritable to work around safely, or of little use for riding when in season, there are other options.

Spaying (removing the ovaries) will eliminate sexual behavior, but isn’t done too often because it involves surgery and obviously is fairly expensive.

Many people turn to giving their mares the drug Regumate. This is a progesterone that mimics the hormonal profile of a pregnancy so the mare doesn’t show in season. It eliminates problems with excessive sexual behavior that interfere with work, but doesn’t do a thing for irritability or touchiness, and may actually make that worse. Elevated progesterone mimics the hormonal profile during human PMS, too, and if you’ve ever been pregnant, you know you don’t exactly always feel positive and energized then either.

Regumate can cause temporary infertility, which will last for a while even after you stop administering it, so bear that in mind if you want to breed the mare. Mares coming off Regumate frequently have cycling abnormalities for many months. That can make them even worse than they were before they started the drug. Another drawback is that care must be taken not to get it on your own skin, where it can be absorbed and cause cycling problems in women, or infertility in both men and women.

If you really need something to control your mare’s seasons, a better first choice is often Chastetree Berry. Try a half-ounce to one ounce per day of the ground berries from a bulk herbal supplier like HerbalCom,, or use an equine product like Hormonise from EquiNaturals,, or Evitex from Emerald Valley, This botanical is usually very successful in regulating cycles and toning down both behavior problems and irritability. Other mare supplements use different herbs, including many calming ingredients. These options are definitely worth trying.