Calming Supplements for Mares (from AAEP Ask the Vet)

I own a 22 year old Appendix mare. She has always become very irritable during her first heat cycles in spring. We’ve had a “marble” implanted in her a few years ago which helped a lot then, but now I’m looking for something less invasive. I am wondering about starting her one of the “Moody Mare” type calming supplements. Do you feel they are effective? Any ingredients I should look for? Any thoughts on Valerian vs Valerian free- (we don’t show)? Thanks so much!


Dear RS,

Have you tried using prescription Regumate during the transitional period of spring? This synthetic progesterone is specifically labeled for managing the irregular cycles and behavior of mares as increased daylight causes them to enter the normal breeding season.

If you prefer to use a non-prescription supplement, look for products that contain Vitex agnus castus and/or Raspberry leaf. Also known as Chasteberry or Monk’s Berry, Vitex agnus castus is a plant native to the Mediterranean region that has been used for centuries to help maintain a balanced hormonal system in both females and males. Horse owners use it for both irritable mares and aggressive geldings. Raspberry leaf is an herb primarily used for its benefits to females. Believed to temper the effect of hormonal variations, the active ingredients in the plant appear to normalize smooth muscle tone in both the reproductive and GI tracts, relaxing muscle that is in spasm and strengthening muscle that is weak.

You specifically asked for my thoughts on Valerian. In my opinion, Valerian is more of a general calming herb. In fact, it is what’s called a “nervine,” or, an herb that directly affects the nervous system. Valerian rebalances a nervous system struggling with restlessness, anxiety and, in humans, even insomnia. The reason it may be included in many supplements for moody mares is that it also relieves muscle cramps and spasm associated with tension.

You won’t know what works for your individual mare until you try, so choose one product this spring and keep a journal of her behavior so you know what (and what not) to use next spring.

Lydia F. Gray, DVM MA, currently serves as the Medical Director/Staff Veterinarian for SmartPak Equine. Prior to joining SmartPak, Dr. Gray served as the first-ever Director of Owner Education for the American Association of Equine Practitioners. She has authored numerous articles in publications such as The Horse, Horse Illustrated, Western Horseman and a variety of veterinary journals and magazines. Dr. Gray is also a frequent speaker at horse expos, veterinary conventions and other locations. After graduating with honors from the University of Illinois College of Veterinary Medicine and receiving her Master's Degree in Interpersonal and Organizational Communication, she practiced at the Tremont Veterinary Clinic for several years. Dr Gray is active in the American Veterinary Medical Association and Illinois State Veterinary Medical Association and enjoys training and showing her trakehner Newman in her spare time.  Find Dr. Gray on Google+

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