Your horse is getting on in years. You’ve noticed that the winter coat is longer than it used to be. To complicate matters, he doesn’t shed out like he used to. Last year, you needed to body clip your horse. That was a tedious, messy job that took forever. Is there anything that can help? Chastetree berry may help.
◆︎ What is chastetree berry?
Chastetree berry (sometimes called chasteberry) is a natural herb that affects the endocrine system and the reproductive system. The active ingredients, the diterpenes, bind to the dopamine receptors on the pituitary. It fools the pituitary into thinking that there is more dopamine than there really is, thus alleviating many of the symptoms.
◆︎ What might you see if you put your horse on chastetree berry?
➡ Horse’s coat: Chastetree berry can affect the coat. Usually, older horses have long wavy coats that don’t shed readily. After 6-8 weeks on chastetree berry, many people find that their horse sheds out normally, with the new growth looking more like normal hair instead of the long wavy hair. This is a big advantage, because many people don’t have the time, equipment, or stamina to clip their horse several times a year.
➡ Lethargy, depression, and loss of spark: Many older horses seem to lose their spark. They tire easily. They aren’t as peppy as they once were. It’s easy to attribute that to the aging process, but many horses will rebound in their attitude and energy level with chastetree berry on board.
➡ Muscle wasting and the pot-bellied appearance: Uncontrolled PPID can cause muscle wasting. Chastetree berry may be able to retard the muscle loss. While it cannot rebuild muscle, it can help stop the deterioration, improve the attitude, and the peppiness, which may help the horse become more active to rebuild muscle.
➡ Excessive drinking and urination: Horses with uncontrolled PPID may have the symptoms of excessive drinking and urination. This isn’t just a housekeeping issue. It’s hard on the horse, creates an environment that negatively affects the hooves, and the increased ammonia can cause respiratory challenges.
➡ Supporting the immune system: Chastetree berry indriectly affects the immune system. By reducing the stressors on the horse, the horse’s immune system may be able to function better. This may help the horse have a more robust immune system, leading to better health. Some people report that their horse has fewer allergies, a more robust response to pathogens, and better overall health.
➡ A mare that has swollen udders, lactates, or has other reproductive issues: Dopamine inhibits prolactin secretion. Because chastetree berry mimics dopamine, it may have a positive effect on the mare’s reproductive system and symptoms.
◆︎ The caveat:
While chastetree berry may alleviate symptoms that you see in the horse, studies have shown that it does not lower ACTH levels. The gold standard to lowering ACTH levels and treating PPID is to use pergolide (the brand name in the USA is Prascend®). Both
pergolide and chastetree berry bind to dopamine receptors. If you are administering both, you risk that the pergolide is not as effective, since the chastetree berry and pergolide compete for the same receptor sites.
◆︎ Why might you use chastetree berry?
There are many reasons why a person would choose chastetree berry when pergolide is available. These may include:
» Pergolide is available by prescription only. Some rural areas do not have regular veterinary access to test for PPID.
» Some people may add chastetree berry during the spring to help with shedding.
» Some people have found that they have better symptom control by using both.
» Some people have other personal reasons that they choose to use chastetree berry.
◆︎ Consult your veterinarian
If you have issues that nutraceuticals do not help, please consult your veterinarian. He/she will be able to give you a diagnosis and treatment plan to help your horse.
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Disclaimer: Statements regarding dietary supplements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease or health condition.
©Joan Kulifay, MSc. 2026