Equine Cushing’s Disease


What is Cushing’s Disease?

A horse with a hairy coat, a common symptom of equine Cushings disease.

A horse with a lengthy coat of hair, a common symptom of equine Cushing's disease.

Equine Cushing’s Disease is one of the most common hormonal disorders that occurs in horses. It is normally due to a tumor, or an increase of cells in the region of the pituitary gland. The tumor or increased number of cells results in the increased production of the stress hormone Cortisol, or mimicking cortisol-like compounds by the adrenal glands which are located near the horses’ kidneys.

Signs of Cushing’s Disease

The most common sign of Cushing’s Disease in horses can be detected from the horse’s haircoat. Anything from abnormal shedding to a wavy coat length can be a sign of Cushing’s Disease. A common sign is a horse that fails to shed in the summer compiling a lengthy coat of hair. Increased urination is also a common sign as Cushing’s may cause a horse to surpass the normal 5-8 gallons of water which is the common amount consumed by horses daily. Loss of muscle and the appearance of a pot belly are also occasional signs of the development of the Cushing’s Disease in horses, as well as chronic or relapsing Laminitis. Although not restricted to older horses, Cushing’s Disease is most commonly found in aging horses.

Causes of Cushing’s Disease

The pituitary gland is located near the base of the brain and is often referred to as the “master gland” because it controls the body’s hormonal system. It is most commonly believed that the cause of Equine Cushing’s Disease is the development of a tumor in the pituitary gland which causes the adrenal glands near the kidneys of horses to produce too much of the stress hormone known as Cortisol. The normal functions of Cortisol in a horse range from regulating blood pressure, heart function, and metabolism to regulating muscle tone and helping the body respond to stress. The overproduction of Cortisol is what causes the Equine Cushing’s Disease and its toll on horses.

Dangers of Cushing’s Disease

If not managed properly, horses with the disorder may expect to live between 5-7 years. Failure to manage the disorder according to proper conduct can result in a dramatic decrease of life expectancy. It is also possible that if the tumor increases greatly in size, the horse may become blind.

Treatment/Proper Management of Equine Cushing’s Disease

Although there is no cure for Cushing’s Disease in horses, prescription treatments such as pergolyde mesylate and trilostane aim to decrease Cushing’s severity by decreasing the overproduction of hormones. It is very important to make regular veterinary appointments for the affected horse. In addition it is essential to ensure a properly balanced diet, especially considering that some horses with Cushing’s Disease are Insulin Resistant and susceptible to reoccurring Laminitis.

Natural options for Cushing’s Disease

Researchers at Texas A & M discovered reining horses fed a diet high in OMEGA-3 fatty acids had decreased inflammatory responses including decreased Cortisol concentrations following exercise.  Other researchers have concluded horses afflicted with arthritis, laminitis, colic and enteritis benefit from diets high in OMEGA-3 fatty acids.  Equi-Bloom is a highly stable, flavored OMEGA-3 fatty acid supplement for horses.  Additionally, vitamin A, vitamin E, selenium, and zinc are included in Equi-Bloom to replace any deficiencies in the diet.

Approximately 80% of Cushing’s cases have a low total thyroxine (TT4).  It is imperative that its value be within the normal range for other treatments to be effective.  Equithrox is a palatable, readily consumed equine thyroid supplement.  Many veterinarians prefer Equithrox thyroid supplement as a source of Lthyroxine sodium due to its apple and molasses flavored base.  Competing products are not flavored and therefore less likely to be consumed by the horse.

Metaboleeze is an ideal supplement for horses with Cushing’s Syndrome.  Horses afflicted with Cushing’s Syndrome often develop glucose intolerance and therefore have difficulty processing sugars and starches found in typical feeds.  Metaboleeze helps Cushing’s horses by lowering circulating levels of insulin, thereby improving insulin sensitivity.  When used in conjunction with typical therapies (pergolide or cyproheptadine), evidence suggests that Metaboleeze corrects Insulin Resistance more rapidly.