Equine Cushings Disease

Equine Cushing's disease, also known as Pars Pituitary Intermedia Dysfunction (PPID) is a disorder of the horses’ endocrine system (hormonal system). Equine Cushing’s most commonly affects pony breeds, but larger breeds can be affected and it is mostly seen in older horses above the age of 15.

Cushings is caused by an enlargement in the pars intermedia (middle section) of the pituitary gland. The pituitary gland is located at the base of the brain and is an important endocrine organ that produces a variety of different hormones. This enlargement results in the increased release of several hormones, most notably ACTH (adrenocorticotropic hormone). ACTH causes the adrenal glands (located near the kidneys) to increase the production of cortisol, a type of steroid. It is this overproduction of cortisol that causes the majority of clinical signs seen in this condition.

There are many clinical signs associated with Cushing’s disease. Recurrent and unexplained bouts of laminitis along with an abnormal hair coat are two of the most common clinical signs.Other signs include a pot-bellied appearance, ravenous appetite, increased urination and drinking, lethargy and a decrease in the immune system seen as recurrent skin and respiratory infections, as well as dental disease and an increased susceptibility to worms.

Horses with Cushing’s Disease can exhibit a variety of symptoms, with an excessively long and curly hair coat that fails to shed in the summer being the most recognisable one. Other symptoms include:

Weight loss due to loss of active back muscle, seen as a swayback and potbelly

Excessive body fat

Development of insulin resistance which can lead to laminitis

Polydipsia/polyuria (excessive thirst/urination)

Blindness

Weakened immune system; delayed wound healing, chronic infections

Behavioural changes such as lethargy

Reproductive disorders

In classic cases (an older pony with recurrent laminitis) a diagnosis can be made on presentation alone, but not all Cushing's cases have obvious clinical signs - often they are very subtle. When investigating subtle signs, or when a definitive diagnosis is wanted, there are a couple of tests our vet can conduct.

A variety of tests are available to diagnose Equine Cushing’s Disease. These include a blood test to identify hyperglycaemia (high blood sugar levels) and a urinalysis to detect abnormally elevated levels of glucose and ketones in the urine. More specific hormone-related tests might be performed to confirm the diagnosis of Cushing’s disease following a repeat blood test to establish the consistency of high blood sugar.

Unfortunately there is no cure for cushings disease, however the disease can be managed. Management is just as important as medicating. Frequently inspecting for wounds and the evidence of any kind of infection and ensuring prompt veterinary attention is very important as affected horses may have reduced levels of immunity and often need more intensive and prolonged treatment than other horses.

Regular farrier visits and dental checks along with routine vaccinations and a de-worming program involving frequent faecal egg counts are vital to ensure the health of Cushing's affected horses. Simple things like clipping out excessive hair will also go a long way in ensuring the comfort of affected horses especially in hot weather.

We are here to help. If you would like more information or are concerned on the wellbeing of your horse - contact the clinic to arrange a time for Dr Andrea to have a chat or a visit.