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Mare and foal
Mare and foal with square bale
My good friend Kate insists that she only likes mares. “Only mares, no geldings, no thank you!” I always thought she was crazy. I mean, why would you want to put up with an animal who was testy and irritable more than half the year? As a woman, I sympathize with mares’ cycles, but I love my always-the-same, ploddy, mellow gelding, so I really didn’t get her perspective. “Because, they have that oomph! You know, they have that extra boost to keep them going, while gelding are just … well boring!”
The good news is that Regumate, one of the more popular equine progesterone treatments for mares on the market, is not the only option you may have to regulate her cycles.
To understand fully how these drugs work, first, let’s briefly review the science behind mares’ cycles—when they happen and why. Mares typically have their seasons between April and September in North America. The rest of the year, their cycles are normally dormant. The timing of this activity is related to the amount of daylight during any period during a calendar year. This is why a mare’s shedding season often correlates with her going into season. A mare’s cycle also lasts 21 days (not 28 days, like a woman), with typically 5 days of being in “heat,” and exhibiting various forms of irritability.
You can prepare your mare in advance for her cycles, and everything that comes along with them. If you are looking for a herbal remedy for her, it is best to start her on the herbs as she is entering her cycles, especially if the purpose of the supplement is to balance her hormones, versus ease her symptoms and make her more comfortable. Herbal supplements must be used for over one month before you may see a major change (give herbs two cycles, or six weeks). Herbs work in an additive way, where prolonged use over time will compound so that you see an eventual change, as the horse’s body absorbs more of the ingredients.
What kinds of herbs are ideal?
It completely depends on what you are treating. Do you know why your mare is irritable? Is it a hormonal imbalance or is she simply uncomfortable? Us ladies know how bad cramping can be, and it certainly can make us irritable and low energy as well even if our cycles are regular. You should consult with your veterinarian and keep a journal of your mare’s cycles and symptoms so that you can figure this part out. Please note that mares can have abnormal cycles during the transitional periods as well- at the beginning and end of the cycle season.
Herbal Solutions
For mares with hormonal imbalances that cause issues, this is what is recommended:
Chaste Tree Berry — Chaste Tree Berry has been shown in multiple studies to regulate the pituitary gland, and as such is often a recommended treatment for Cushings, but can also be very helpful for hormonal balances. The pituitary gland regulates hormones in horses, and this herb can act as a progesterone-creator of sorts, so as to even out the effects of hormonal changes throughout the cycle. Of the herbal remedies, this one is the closest to Regumate in how it works on the mare’s cycles.

Andrea Baldwin
Chaste Tree Berry
Chaste Tree berry
For mares whose irritability may be physical in nature, such as cramps, back pains, etc., it would likely be more effective to feed her herbs that are anti-inflammatory and calming so that you can ease her pain. If one does not produce the desired results, try another herb—and remember, not all herbs interact with each mare’s body in the same way.
Vervain, Cramp Bark, Yarrow, Rosemary, Lemon Balm — These herbs are known to relax the uterine muscle and be antispasmodic. Top-dress her feed with dried flowers or an herbal powder or infuse in water and add to feed.
Valerian, Chamomile — Chamomile is known for its anti-inflammatory properties and can help with cramps and uterine bloating. These herbs are also used commonly for reducing anxiety and stress, which of course can be an issue for mares in pain. Top-dress her feed with dried flowers or an herbal powder or infuse in water and add to feed.
Rasberry Leaf, Blue Cohosh — Both herbs are known as a “uterine tonic” for mares; they both contains alkaloids that strengthen the uterus and pelvic region that can help with making your mare less susceptible to cramping/relieve the intensity of the discomfort. The best way to feed Blue Cohosh is in liquid form; Rasberry Leaf can be fed as a tea or in the form of a dried herb. Since these both help strengthen the uterine area, it may be advised to feed these even while your mare is not on her cycle.
Dong Quai — Often prescribed by acupuncturists for women, this Chinese herb contains ferulic acid that can relieve cramping and relax the uterine muscle. The most common way to feed this is via an herbal powder.
Dandelion Leaves — Dandelion is a known diuretic and liver cleanser. Mares may experience water retention during their menstrual cycle and this can help to relieve symptoms. Additionally, the liver regulates hormones and can help balance your mare’s cycles out.
There are many supplements on the market that include these herbs or you can purchase these herbs separately and feed them. Be sure to consult your veterinarian prior to use, especially if you are planning to breed your mare or if she is pregnant, as some of these herbs can have a negative impact on pregnancy. Lastly, enjoy your mare, embrace her cycles, and, in my friend Kate’s words, take the oomph with the spice!
Many of these herbs have contraindications. Please reference an authority before using any herbs.
Melanie Falls is a holistic health aficionado and advocate, having healed her own horse, 21-year-old Desario, with natural methods. Melanie writes articles for various equine publications and online blogs and is the owner of Whole Equine, an online store featuring a large catalogue of top quality, all-natural horse care products including supplements, fly sprays, first aid, and much more. She offers free consultations to all her customers and is passionate about improving the lives and health of our large four-legged friends. https://www.wholeequine.com, info@wholeequine.com, 844-946-5378