Equine Pituitary Pars Intermedia Dysfunction: PPID

Foundation takes a new look at an old disease

For many of us old enough to remember, Equine Cushing’s disease, as it was known at the time, was an oddity, something unusual and uncommon. Flash forward several decades and the evidence suggests that this disease is much more common than previously suspected. Estimates suggest that upwards of 15%-30% of horses over the age of 15 have equine pars intermedia dysfunction (PPID), the new term for this disease. In fact, the disease is now considered the most common endocrine (gland) disorder affecting equids.

As the name suggests, PPID is a disease of the pituitary gland, a small organ located in the brain. The pituitary gland produces and stores hormones crucial to many different bodily functions, including metabolism, reproduction and growth. One of the hormones produced by the pituitary gland is adrenocorticotropic hormone (ACTH). In PPID, the pituitary becomes diseased and begins to produce too much ACTH. ACTH has many actions, including increasing production of cortisol. Excess cortisol in turn leads to numerous clinical signs associated with this disease, including:

  • Hair coat changes
  • Lethargy
  • Behavior changes
  • Muscle loss
  • Pot belly
  • Recurrent infections
  • Laminitis

PPID can be diagnosed through specialized blood tests in combination with clinical signs. Many of the tests can be performed in the field and don’t require referral to a specialty clinic although, occasionally, that is needed for some very specific tests.

PPID is treatable but not curable, and therapy is lifelong.

Because of PPID’s importance to horse and pony health and well-being, Morris Animal Foundation decided to make it a focus of the Foundation’s latest call for equid health proposals.

“PPID is an important disease to study because it’s so common,” said Dr. Nicola Menzies-Gow, Professor in Equine Medicine at the Royal Veterinary College, United Kingdom. “And PPID causes clinical signs which can have a significant impact on the affected animal’s quality of life.”

Although the equine medical community has recognized PPID for decades, many unanswered questions remain. This is where the Foundation stepped in and reached out to veterinary scientists to submit projects aimed at tackling PPID.

“There are still a lot of big questions about PPID that need answers,” said Dr. Menzies-Gow. “For example, we don’t know what actually causes PPID. We also need a diagnostic test that can detect the disease with 100% accuracy in all animals. And we need more information about how our current treatment affects the risk of laminitis.”

Dr. Menzies-Gow is one of the equine medicine experts assigned to review project proposals submitted to Morris Animal Foundation. Each proposal is carefully scrutinized and then, if the proposal clears the high bar set by the Foundation, it is recommended for funding. Only the very best grants achieve this level of distinction.

The review board will begin reviewing the submitted proposals soon and the whole team, including Foundation staff members, will convene in March 2023 to rank proposals for funding. A wide range of subjects, from looking at the genetics of PPID (with an eye toward identifying genes associated with increased risk of disease) to evaluating new treatments, are included in the proposal packet.

It’s clear that PPID has risen from oddity to important disease of equids, and that it has a larger impact on health and welfare than previously suspected. Morris Animal Foundation is excited to contribute toward improving the quality of life for thousands of horses and ponies through our new grants!

[Read more about the diagnosis and treatment of PPID here.]

Brought to you by Morris Animal Foundation




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