Chaste tree berry is a type of herb that has medicinal qualities. It is often fed to horses to treat the symptoms of Cushing's disease, which is the result of a hormonal imbalance, usually in older horses.
Cushing's disease happens when unusual growths occur on the pituitary gland, which then produces too much adrenocorticotropic hormone (ACTH). The ACTH causes the adrenal glands to produce cortisol, which has adverse effects on the horse.
A horse with Cushing's disease often will have a long, wavy coat that won't shed in the spring. Other symptoms are excessive sweat, lethargy, chronic laminitis, weight loss, and drinking and urinating excessively.
Chaste Tree Berry
According to the PubMed website, a study showed that extracts of chaste tree berry are beneficial for premenstrual symptoms in women, which shows that the berry can suppress some types of hormones.
The Vet Herb website recommends trying chaste tree berry to help lower levels of cortisol. The site recommends 20 ml of a 1-to-2 extract of the berry given twice a day.
The Farrier Vet website recommends testing the horse's insulin and cortisol levels every six weeks while using chaste tree berry. The amount or potency of the extract should be adjusted based on results of the tests.