How to Diagnose and Treat Equine Cushings Disease
Cushings disease occurs in horses, dogs and even people. However, the symptoms are different, depending on the species. In horses it results in increased hair growth (longer, thicker, curly) whereas in dogs it results in hair loss and even bald spots. The horse version of this illness is called ECD (Equine Cushings Disease).
As a horse ages, there is an increasing tendency for the pituitary gland to develop tumors or to grow too large, resulting in it producing more hormones. This in turn stimulates the adrenal glands to produce additional steroids and when the level of steroids becomes excessive it results in cushings. Since these changes are age related, ECD is most often found in horses over 15 years but has been found in horses as young as seven.
The disease cushings is named after Harvey Cushing, who identified and explained the disease in’21. ECD is simply the equine equivalent of the disease which Dr. Cushing first identified in humans.
The symptoms of cushings disease vary somewhat from horse to horse, with the more common symptoms including: – Changes to the coat. It may become longer and curly. It may not be shed in Spring. In some cases the color becomes lighter. – Increased sweating. This is often due to the coat become longer and thicker, and retention of the winter coat into summer. – Weight loss despite increased appetite and food consumption. Changes to the body shape, with loss of muscle in back and neck, and development of pendulous abdomen. – General depression, loss of coat shine, horse looks ill. – Development of diabetes and a resulting increase in water consumption. This can be difficult to detect with pastured horses, but with stabled horses one may notice an abnormal amount of urine (or soiled bedding) in its box. – Development of laminitis. The most common cause of normal laminitis is carbohydrate overload due to eating spring grass, whereas ECD-caused laminitis is more frequent in autumn and winter since ECD is worse when the days are shorter (this is because the pineal gland is light-sensitive and as daylight decreases it stimulates the pituitary gland). – Immune system declines, leaving the horse more prone to infections and slower to heal from external injuries. – The depressions above the eyes fill in. These depressions are most evident when a horse is chewing, but gradually fill in with fat in ECD horses.
Studies have determined that many older ponies (and to a lesser extent horses) have ECD but have not been diagnosed, with the result that they were not receiving controlling treatment in the early stages of the disease (the point at which treatment is most beneficial). Increased care is needed with older equines to identify ECD promptly. Although this can be done by careful observation of potential symptoms, blood and urine tests are often used to confirm that the cause is ECD and not some other disease.
ECD cannot be cured. However, the hormone levels can be reduced to more normal levels through medication, slowing the progress of the disease. As some of the medications can have serious side effects (e.g. liver disease), one needs to monitor for any such side effects and change the medication accordingly.
One also needs to watch for symptoms of secondary diseases, such as laminitis or diabetes, which are more common in horses with ECD. These need to be treated promptly to prevent them from further damaging the horse’s health.
One should also maintain the horse’s quality of life by treating any symptoms which make it uncomfortable. For example, if the heavier coat results in the horse becoming too warm, one should clip the coat in spring or summer.
Dr. Douglas Stewart is the author of Cushings Disease in Horses and owner of Horses for Sale
