Cushing's disease, or syndrome, is not a welcome diagnosis for any horse owner. As of 2010, the symptoms are treatable, but the condition is not curable, with symptoms progressing as the horse gets older. Chasteberry is emerging as a promising herbal treatment for this endocrinal condition. Studies of the herb, known to affect dopamine levels in humans, indicate it has the same effect in horses and can help regulate the pituitary gland.
Older horses are more likely to get Cushing's disease than younger horses. Cushing's occurs when the pituitary gland is no longer able to regulate bodily functions properly, evidenced by such symptoms as excessive sweating, an inability to shed seasonal coats, depression or other mood changes, and excessive thirst and urination. Affected horses can develop tumours in the pituitary gland that can cause neurological problems and have compromised immune systems that lead to a host of additional health issues.
A veterinarian will probably provide counsel on any dietary changes a Cushing's horse requires, as well as any supplements necessary to support its immune system. Advancements in traditional medications can treat symptoms associated with Cushing's, but owners might want to talk to their veterinarians about trying a regimen of chasteberry, or Vitex agnus-castus.
One trial in the U.S. on 10 horses afflicted with Cushing's yielded improvement in all 10 horses after they were treated with chasteberry. According to LuAnn Groves, DVM, there should be a noticeable improvement in the horse's condition in about four to five weeks if it is going to respond favourably to chasteberry.
Dr. Groves, of the Whole Horse Clinic in San Marcos, Texas, believes chasteberry treats not just the symptoms associated with Cushing's but the condition itself. She will dose a Cushing's horse with 1 tbsp a day, twice a day, every day for the horse's remaining years. If the horse has more advanced symptoms, such as showing early signs of laminitis, Dr. Groves advises a "loading dose" of 2 tbsp, twice a day, for a week, and then lowering the twice-daily dose to 1 tbsp.
While Dr. Groves indicates that she has not noticed any negative side effects in horses she has treated with chasteberry, as with any drug or treatment regimen, owners should monitor their horses' conditions and report to their veterinarians if they notice any changes. Highest quality chasteberry should be purchased from a reputable source.