Equine Cushings Disease - Symptoms and Treatment

Cushing's disease occurs in various animals (e.g. dogs, horses, people), although the symptoms in horses are different than the symptoms in other animals (e.g. in dogs it results in hair loss whereas in horses it results in greater hair growth). When the disease occurs in horses, it is known as Equine Cushings Disease (or ECD).

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.

Each of these symptoms could be caused by other illnesses, so it is often a combination of them which results in ECD being diagnosed. Urine and blood tests can be used to rule out other possible causes and to confirm the presence of ECD. Studies have found that many older horses (especially ponies) have ECD than are diagnosed. Consequently, greater care is required to identify ECD in the early stages, when controlling treatment is effective.

Although ECD is not curable, it can be treated. The most common treatment is the use of medication to reduce hormone production to near normal levels, thereby slowing down the development of secondary problems.

As cushings disease can result in the development of secondary diseases (e.g. laminitis, diabetes), the horse needs to be closely monitored for any symptoms of these, with appropriate and prompt treatment.

Management of the symptoms can make the horse more comfortable and increase its quality of life. For example, if the horse cannot shed its winter fur and consequently over-heats in summer, the coat should be clipped.

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