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Cushing’s Syndrome

What is Cushing’s syndrome
Cushing’s syndrome (also called Hyperadrenocorticism) is a disease of the endocrine system. It is caused by an abnormality of the pituitary gland, at the base of the brain, which makes the body produce excessive amounts of cortisol – the body’s natural steroid hormone.

What are the signs of Cushing Syndrome?

  • Increased thirst.
  • Increased appetite.
  • Increased urination.
  • Pot bellied appearance.
  • Loss of top-line muscle.
  • A thick wavy hair coat in the summer – failure to shed the winter coat.
  • Chronic laminitis.
  • Lethargy.

How is the disease confirmed?
The test regime we now recommend is to measure endogenous ACTH, cortisol, insulin and glucose from venous blood samples at 0900 hours before the morning feed and in a quiet environment. This is a simple test to use, although the blood cells have to be separated from the plasma and the sample kept frozen prior to testing. This test does not run the risk of inducing or worsening laminitis following the administration of a corticosteroid. It will differentiate between pituitary dependent Cushing’s cases and those animals with obesity related laminitis.

Is it treatable?
There are a number of treatments available for the treatment of Cushing’s disease. The principle behind each treatment is very similar. Each treatment is life-long. Within the brain a substance called Dopamine prevents overproduction of hormones. Serotonin is another naturally occurring substance, which has the opposite effect. So, to treat your horse you can either use a drug which mimics dopamine (Bromocriptine or more commonly used, Pergolide) or a drug which blocks the effect of Serotonin (Cyproheptidine). Trilostane, a drug that blocks cortisol, is another alternative, which is about to be licensed in the UK.

How can you help?
The increase in cortisol is similar to the effects of stress; decreasing the stress experienced by your horse help minimise the effects of the disease. Reduce stress by:

  • Sticking to a strict routine.
  • Provide a safe comfortable, quiet haven for the horse.
  • Avoiding turnout with aggressive horses.
  • Keeping feed and water conveniently located.
  • Clipping the horse in warm weather and using rugs when cold.
  • Keep the horse well groomed to minimize skin disease.
  • Inspect the hooves daily, keep in good shape, and monitor for signs of laminitis (see above).
  • Minimize contact with new horses.
  • Immunize as necessary.
  • Worm regularly.
  • Check dental health.
  • Provide a high quality, easily digestible diet.

Prognosis and Long Term Outcome?
Treatment is lifelong, as is management. This condition cannot be cured but horses can continue in comfort for many years. Laminitis is the most serious complication.

DISCLAIMER: This advice is intended for use by registered clients of Priors Farm only. The advice offered is general advice only. Priors Farm clients who wish to discuss the individual circumstances of their horse should contact the office. To speak to a vet please phone between 8.30 – 10.00 am on weekday mornings.