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Equine Cushing’s Disease is the most common problem affecting the endocrine (hormonal) system of horses and ponies.

Cushing’s disease is usually caused by a degeneration of the hypothalamus and pituitary gland in the brain of older horses and ponies resulting in a failure of control of hormones including dopamine and ACTH. This leads to abnormally high amounts of these hormones being produced. The disease has more recently and correctly come to be known as Equine Pituitary Pars Intermedia Dysfunction or ‘PPID’.

Although PPID is usually only seen in horses over 15 years of age we have occasionally diagnosed it in horses as young as 7. It is thought that up to 40% of horses over the age of 15 may be affected.

Clinical signs:  One of the most common clinical signs is the development of an abnormal hair coat - sometimes progressing to a full, long, curly, overgrown coat (‘hirsuitism’)that isn't shed in the summer.  The presence of hirsuitism is probably the most reliable indicator of underlying PPID do not develp this symptom.

Abnormal fat distribution is another common finding. This includes fat bulging above the eyes (‘supraorbital fat’) and a pot belly.

Other common signs are:

v     Excessive sweating

v     Increased appetite

v     Increased drinking and urination

v     Lethargy/poor performance

v     Repeating episodes of laminitis

v     Recurring infections

v     Loss of muscle condition

Diagnosis may be made from clinical signs based on a full examination and history or by diagnostic blood testing. There are two tests which may be carried out. One requires a single blood sample and the other comprises a blood sample, injection of steroid then a further blood sample the following day.

Whilst it was traditionally beleived that eating high levels of carbohydrates was the main trigger for laminitis it is increasingly thought that some horses develop laminitis because they are predisposed by an underlying endocrine problem ie.  PPID or Equine Metabolic Syndone - a condition similar to type 11 diabetes in humans.

A recent study showed that over 70% of horses examined by vets for laminitis may have underlying PPID.

Early identification of horses and ponies with PPID helps to identify and slow the disease early in its course. Although there is no “cure” for the problem, appropriate medical treatment and good routine healthcare can help keep your horse healthy and fit.

Medical treatment

The only licensed treatment for PPID is a tablet called Prascend(pergolide) which acts directly to lower cortisol levels in the blood.  This comes in the form of a tablet which usually given once daily, although after a period of treatment some horses can be maintained on a lower dose.  Some horses will also require medication to treat associated laminitis or Equine Metabolic Syndrome.

Management changes for horses with PPID

Most horses and ponies with PPID are older than 15 years, and so may have other conditions associated with middle age, as well as symptoms directly associated with the disease. With this in a mind, a good programme of routine preventative health care can be a great help in managing a horse with PPID. This should include:

• Regular worming, dentistry, and routine foot care (especially for laminitics)
• A high quality, balanced, diet. Ask your vet for advice.