PPID (formerly known as Equine Cushing’s Disease)

Pituitary Pars Intermedia Dysfunction is one of the most common diseases of the endocrine system that can affect horses.2 PPID causes the horse's pituitary gland, which utilizes hormones to control body functions, to work overtime. This can lead to a variety of problems for horses, ranging from unexplained laminitis to an abnormal fat deposits. PPID affects both male and female horses, all breeds and horses as young as 7 years of age.1

A horse doesn’t have to be older to be susceptible to PPID

Horses as young as 7 years of age1, have been diagnosed with PPID. Earlier diagnosis may offer horses suffering from the disease a better quality of life, so ID PPID early.

The Clinical Signs of PPID

Clinical signs of PPID that may lead to earlier reconigition and diagnosis may include:

  • Decreased athletic performance
  • Change in Attitude/Lethargy
  • Delayed hair coat shedding or regional hypertrichosis
  • Laminitis
  • Laminitis may occur in both earlier and advanced PPID and has been shown to be associated with concurrent insulin dysregulation

Studies have shown that the clinical signs of PPID are often under-recognized.2

  • What is Pituitary Pars Intermedia Dysfunction (PPID)?

    PPID is the most common endocrine (hormonal) disorder in horses and ponies.

  • What causes the disease?

    The hypothalamus and pituitary gland, which sit deep inside the skull at the base of the equine brain, are the command center for the production of hormones. These chemical messengers are distributed around the horse’s body via the bloodstream to all other tissues. In a normal horse, these exist in a fine balance, and play an important role in maintaining and controlling bodily functions.

    In some horses and ponies, neurons (nerves) in the hypothalamus undergo progressive degeneration, and produce insufficient quantities of a nerve transmitter substance (neurotransmitter) called dopamine. Dopamine is important in controlling the secretions of a part of the pituitary gland called the pars intermedia, which in turn is responsible for controlling the secretion of hormones including adrenocorticotropin hormone (ACTH).

    When the pars intermedia is not exposed to enough dopamine from the hypothalamus, it results in the production of abnormally high levels of these hormones, resulting in the clinical signs associated with the disease.

    Equine Cushing’s disease is currently referred to as PPID (Pituitary Pars Intermedia Dysfunction) due to the specific anatomic location that is affected in horses. The pathoetiology of Cushing’s disease in the dog and human is caused by dysfunction of the pars distalis, rather than the pars intermedia in the horse.

  • How common is PPID?

    Studies of horse populations suggest that 15%-30% of horses and ponies 15 years of age and older are affected by the disease. Reportedly, horses as young as 7 years of age have been diagnosed with PPID.

Take advantage of our testing offer this spring

Veterinarians can request up to 3 tests for horses suspected to have PPID

Equine Endocrinology Group recommendations for diganosis and treatment of PPID

For full diagnosis recommendation protocol, visit the Equine Endocrinology Group (EEG).


1) Schott HC. Pars pituitary intermedia dysfunction: challenges of diagnosis and treatment. In: Proceedings from the 52nd AmericanAssociation of Equine Practitioners Annual Convention; December 2–6, 2006; San Antonio, TX.

2) Ireland, J.L., et. al. Comparison of owner-reported health problems with veterinary assessment of geriatric horses in the United Kingdom.In: Equine Veterinary Journal; ISSN 0425-1644. 2012.