Cushing's disease (PPID) in horses

Horses affected by the hormonal disease PPID, formerly known as Cushing's disease, often have winter fur all year round and find it difficult to regulate their body temperature. But it is possible to medicate and the prognosis is good for many horses - you can read more about the disease here.

PPID (Pituitary Pars Intermedia Dysfunction) is an endocrine disease, which means there is a hormonal disorder. The pituitary gland produces the hormone ACTH, which controls the adrenal gland's production of, among other things, cortisol (the body's own cortisone). In a horse with PPID, the pituitary gland is often enlarged and has an overproduction of ACTH, which stimulates the adrenal gland to increase its production of cortisol uncontrollably.

In the past it was believed that the disease almost exclusively affected older horses, but today we know that PPID can occur in horses of all ages. Among the horses insured with Agria, over 400 were affected by the disease in 2022.

Symptoms

"Classic symptoms are that the horse has winter fur all year round and it is difficult to regulate body temperature, it sweats a lot, but many horses with PPID have a normal hairline. They can also be tired and sluggish, drink and urinate more," says Anette Graf, who is a horse veterinarian at Agria Djurförsäkring.

Horses with PPID are more susceptible to infections and may have an altered hairline. Even the muscles can be affected, they can get a different abdominal shape and become pot-bellied.

The symptoms are similar to those that horses that receive high doses of cortisone for a long time get, it is a similar type of impact.

PPID is also a common underlying cause of lameness, often in combination with EMS (equine metabolic syndrome) where affected horses have difficulty controlling insulin levels. Therefore, the horse should be investigated for PPID and EMS in case of clinical symptoms in captivity.

Typical symptoms of PPID

Altered hairline, the coat often becomes long and curly
The body shape and muscle mass can be affected so that the horse becomes pot-bellied
Susceptible to infection
Weight loss

Investigation

If the vet suspects that the horse has been affected by PPID, a blood test is taken, where the levels of the hormone ACTH are measured. It is safest to take the samples in the fall.

Treatment

If it is determined that the horse has suffered from PPID, it is an advantage if medication, which reduces the production of ACTH, is started as soon as possible to reduce the risk of the horse suffering from seizures.

"The medicine is given in tablet form and it can take a while to set the right dose. Some horses can be affected by the medicine and have side effects, they can become tired and lethargic, which means that you may have to start with a lower dose and then increase.

"Through blood tests, the effect of the medicine is checked, to see that the horse really gets the right dose.

"It is a lifelong treatment, it is not something you give short-term. But many horses respond well to medication," says Anette Graf.

The prognosis for a horse with PPID

The prognosis is good for those horses that respond well to the medication, as long as they do not suffer from seizures. Most horses get rid of their symptoms and can live a normal life. However, a horse treated for PPID is not allowed to compete.