Chastetree Berry for Horses

Vitex agnus-castus, aka Chastetree, Monk’s Pepper, is a small tree native to the  Mediterranean that produces lilac colored flowers on long stalks which fruit large round berries.

Vitex was mentioned many times in the writings of the ancient Greeks and Romans.  It was also known to 13th century Europe.  The tree grows well in both temperate and subtropical zones.

CTB – Chastetree berries, or simply Chasteberry – have a long traditional history of use to help balance hormonal systems, both male and female. While males and females have different levels of hormones produced by the sex organs, the activity of those organs is influenced by the same pituitary hormones, namely LH and FSH.

Recent research into the actions of CTB extract has shown it supports the activity of dopamine.  Since dopamine regulates LH and FSH secretion, this is believed to be how the plant works.  Dopamine also regulates the secretion of prolactin and hormones from the PPI, the intermediate lobe of the pituitary, i.e. the POMC derived hormones beta-endorphin, alpha-melanocyte stimulating hormone and ACTH.

CTB extract functions as an adaptogen in these hormone systems. Adaptogens are substances that assist in stabilizing physiology and promoting homeostasis.  Homeostasis is a state of equilibrium in which the organism functions optimally.

CTB extract has been well studied for human use and is listed by the German Commission E, a body which provides scientific background on the use of traditional herbal substances.

In horses, CTB extract has the potential to assist the body in maintaining homeostasis in a wide range of situations, including:

  • Ovarian function and female hormone production
  • Lactation
  • Female behavior
  • Male hormone production
  • Male behavior
  • Shedding (under the control of prolactin)
  • Intermediate pituitary lobe hormone production

Vitex agnus-castus is an excellent example of scientific study validating and explaining traditional herbal uses.

Eleanor Kellon, VMD

About Dr. Kellon

Graduate of University of Pennsylvania Veterinary School. Owner of Equine Nutritional Solutions,, industry and private nutritional consultations, online nutritional courses. Staff Veterinary Expert at Uckele Health and Nutrition .
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9 Responses to Chastetree Berry for Horses

  1. corona228 says:

    Can Vitex agnus-castus/Chasteberry be fed with regumate? I’m not that knowledgeable regarding the hormones released during a mares cycle. Not sure if Chasteberry would help or hurt Regumates purpose.


    • Dr. Kellon says:

      They are doing different things. Regumate is a synthetic progesterone. High progesterone blocks the mare from showing “heat”. It is the major hormone in pregnancy and also in PMS in humans. Many mares are depressed/lethargic and have decreased performance with Regumate but it’s an improvement over the raging hormones during their cycles. Chasteberry on the other hand works to bring balances more into normal. It doesn’t prevent estrus, just modifies the behavior. I wouldn’t use them together. Try Chasteberry first . If you see a response but need more, increase the dose.


  2. Beth Burrell says:

    I have a 10 year old mare who has a bad attitude when I pull her out of the paddock. She pins her ears at me and is basically just rude. She gets daily handling. Lots of ground work daily and ridden every other day and her life is excellent. After her ride she is soft and sweet and a complete different horse. I keep quality hay in slow feeders 24/7. Plenty of grazing time when grass is available (we live in the midwest). My vet has checked her out vaginally with ultra sound and finds no issues at all. She also does not have ulcers or anything else but is simply a “bossy” mare towards humans – in the paddock she is bottom of the herd. My vet suggests Regumate because she does have “Cybill” type personality where she is nice one moment and naughty with ear pinning the next. I would like to try to keep things as natural as possible with her and have fed her raspberry leaves with little to no change in her behavior. I see that you mention that Chasteberry helps to control hormones, so I am curious how much to feed her? What form? Do I make a “tea” for her or just simply put it in her grain? Any other advice is appreciated.


    • Dr. Kellon says:

      You could try 3 to 6 g per day (1 to 2 scoops) of this concentrated extract: However, it may not be hormonal. It is very common for horses low on the totem pole in their social group to try to take it out on humans.


      • Beth says:

        That’s interesting that you say that she would take her bottom of the herd out on humans because I often wondered if that was something that could be possible. She is a large 17 hand, built like a tank warmblood and an absolute joy to ride but to be on the ground or near her while she is in her stall she gets aggressive. I’ll try the chasteberry leaves – maybe it will her Thanks for the advice.


  3. M Brandt says:

    I have my PPID and IR mare on CTB supplement for 2 years. She is 33. Can I use pergolide as well?


  4. Dr. Kellon says:

    It can help with symptoms, especially shedding, but is not reliable for lowering ACTH levels and eventually loses effectiveness. It has been used along with pergolide to improve shedding.


  5. Billy Blackman says:

    Does chasteberry help horses with PPID? What about when given along wit Pergolide?


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