Early detection and treatment of Cushing's disease is an essential part of providing a better quality of life for affected animals. The onset of Cushing's disease typically begins in the late teens to 20s, but can start as early as 8 years old. Although several synthetic drugs are available to treat this condition, herbal alternatives such as chasteberry have shown to be viable treatment options. In a clinical study directed by Robert Eustace, FRCVS, after treatment with chasteberry extract, "all owners reported improvement in the demeanor of their animals, they became more active, less depressed and the term 'rejuvenated' was often used by owners."
Cushing's Disease
Cushing's disease, also known as hyperadrenocorticism, is a metabolic disorder caused by an overactive pituitary gland. The pituitary gland is a critical part of the endocrine system that helps regulate hormones. As the disease progresses, benign tumors can form on the pituitary gland, causing pressure to be put on other parts of the brain. A horse with Cushing's disease produces increased amounts of proopiomelanocortin peptides, which in turn stimulates the adrenal glands to overproduce cortisol.
Diagnosis of Cushing's Disease
The onset of Cushing's disease is usually marked with an increased thirst, with affected horses drinking up to 20 gallons per day as opposed to a normal 5 to 8 gallons. They may also have an increased appetite paired with weight loss. The most iconic symptom is the long, wavy hair coat that these horses grow in the winter and fail to shed in the summer. Several diagnostic tests can provide a definitive diagnosis of Cushing 's disease. Dr. Phillip Johnson, a veterinarian from the University of Missouri, has developed a test that measures the levels of 11-beta hydroxysteroid dehydrogenase (HSD) in the tissues, as elevated levels of HSD are a marker of cortisol dysregulation. Other tests available include a dexamethasone suppression test and adrenocorticotropic hormone stimulation to determine abnormal hormone levels caused by an overactive pituitary gland.
Chasteberry
Chasteberry is the fruit of the flowering chaste tree that originates from southwestern Europe and western Asia. Dr. Beatrix Roemhelm-Hamm, from Robert Wood Johnson School, cites the use of chasteberry as far back as 2,500 years to treat hormonal dysregulation. Once used to decrease libido, chasteberry offers an herbal alternative to provide relief of premenstrual syndrome and menstrual discomfort.
How Chasteberry Works
The extract of the berry contains iridoid glycosides, flavonoids and oils that have shown to have an effect on the dopaminergic system both in vivo and in vitro. The dopamine system plays a role in the inhibition of prolactin release and its downstream effects help mediate the hormonal imbalances caused by Cushing's disease, although the exact mechanism remains unknown. Studies conducted by Eustace and Russell both returned results that indicated positive outcomes, including rapid shedding of the winter coats. However, other studies, such as the one completed by a team of veterinarians from the University of Pennsylvania, showed no significant changes in clinical measures of Cushing's disease when a chasteberry extract was compared to a commercially available dopaminergic agonist that is the current standard of care. More research is needed to make a definitive determination of the effectiveness of chasteberry on Cushing's disease.
References
- The Laminitis Trust: Laminitis Trust Clinical Trial Using Vitex Equids in Equine Cushing's Disease; Robert A Eustace and Susan L. Emery
- "The Equine Chronicle Online"; Cushing's Disease-What You Need to Know; Brenda Thoma; September/October 2006
- Equisearch: Cushing's Disease in Horses; Jayne D. Wilson
- "American Family Physician"; Chasteberry; Beatrix Roemheld-Hamm; September 2005
- "Horse Journal"; Herbal Offers Hope for Cushing's Syndrome; Steve Russell; December 2000
- "American Association of Equine Practicioners"; Comparison of Vitex agnus castus Extract and Pergolide in Treatment of Equine Cushing's Syndrome; Jill Beech, et al.; 2002
