CUSHINGS AND METABOLIC SYNDROME

The following fact sheet describes two very common equine hormonal diseases.

Equine Cushings Syndrome (Pituitary pars intermedia dysfunction)

Cushings is a disease seen in older horses. It involves an abnormality in the production of a hormone in the pituitary in the brain known as ACTH. ACTH causes excessive production of cortisol (stress hormone) by the adrenal gland (near the kidney).

Clinical signs include; retained winter coat, laminitis (frequently recurrent/chronic), weight loss, sweating, increased drinking and urination, increased susceptibility to infections, pot belly.

Diagnosis is by taking a blood sample. The first test performed is looking at the level of ACTH. The level of ACTH varies throughout the year. Between August and October the pituitary activity increases a lot more in Cushing’s horses than in normal horses so this is the best time of year to test. Other tests are sometime necessary to confirm Cushings if the ACTH test is inconclusive.

Treatment involves giving a medication called pergolide  daily in the feed. Pergolide is extremely effective in reducing  production of ACTH by the pituitary and therefore reduces  cortisol  levels. There is no cure for Cushings so treatment is lifelong. This is an important disease to be aware  of due to the significantly increased risks of laminitis. The trade name for pergolide is Prascend.

Equine Metabolic Syndrome

Affected animals are typically ‘good doers’. EMS develops in genetically susceptible individuals such as native pony breeds.

EMS is due to insulin resistance and obesity.  Normally insulin is responsible for the uptake of glucose into cells. Excessive body fat produces hormones which reduce the sensitivity of cells to insulin so affected animals don’t respond to insulin as they should, similar to type II diabetes in humans. Fat also produces other hormones such as stress hormones which can make laminitic episodes more likely.

Clinical signs include; obesity, regional fat distribution (crest, tail head, shoulders, prepuce or mammary gland) and chronic laminitis.

Diagnosis is by starving a horse over night, then feeding an amount of glucose, based on the horse’s weight. Two hours later a blood test is taken to measure insulin levels. EMS horses will have a high insulin result.

Treatment mainly involves weight reduction. Weight loss programmes are formulated on a case by case basis and involve calculating energy requirements depending on current body weight and ideal body weight and feeding only hay plus a  vitamin & mineral supplement. Exercise is also very important. In some cases a drug is used called metformin to help weight loss. This drug is thought to improve insulin sensitivity.

If you are suspicious your horse or pony could be suffering from either of these diseases don’t hesitate to contact us at the clinic.