FOLLOWING on from last month’s advice about the dangers of laminitis, Hexham vet Joe Sutton takes a look at one of its major causes – Cushing’s Disease.

Equine Cushing’s Disease is the most common hormonal disorder affecting horses.

The pituitary gland – a small gland at the base of the brain – produces a hormone, ACTH.

ACTH travels in the blood stream to the adrenal glands, near the kidneys, and stimulates the release of steriod hormone cortisol, which has the effect of raising the blood sugar level.

In Cushing’s, the normal control mechanisms fail and the blood sugar level gets too high.

The body responds by increasing blood insulin levels to reduce the blood sugar level back to normal.

Continually high cortisol levels, therefore, lead to persistently high insulin levels – and high blood insulin leads to laminitis.

Clinical signs associated with Cushing’s are varied.

Examples include long, curly hair coat, abnormal fat deposits, such as around the eyes, weight loss, droopy back, excess urination and drinking. The most common clinical sign is recurrent laminitis.

Diagnosis of Cushing’s normally involves a blood test to analyse the level of ACTH in the blood.

This test is widely used and is a very accurate way of detecting if a horse has Cushing’s, although care is needed with interpreting borderline results.

Treating Cushing’s involves trying to reduce the level of ACTH.

One of the most effective drugs to do this is pergolide.

This is an oral medication given once daily in feed.

Dosage varies for each individual and initially the dose may need to be fine-tuned, using further blood tests.

The drug works by increasing the level of dopamine in the blood which acts to decrease the level of ACTH.

The treatment of Cushing’s is a long process and horses/ponies are usually on medication for life.

Recurrent laminitis cases will never be brought under control unless the underlying cause is treated.