Understanding PPID: A Common Endocrine Disease in Senior Horses

In this video, Dr. Cosette Faivre, an internal medicine specialist at Hagyard Equine Medical Institute in Kentucky, discusses pituitary pars intermedia dysfunction (PPID, also known as equine Cushing’s disease) in older horses.

Endocrine disease can significantly affect an older horse’s quality of life and longevity, said Faivre. “So, it’s really important that we are diagnosing and treating these as early and as effectively as possible,” she said.

(Editor’s note: The content of this video is the expert’s approach to the topic. Please consult with your practitioner if you have questions.)

What Is PPID?

PPID is a degenerative disease of the brain that ultimately results in an increased production of corticosteroids or stress hormones. This disease is common in senior horses.

PPID affects two sections of the brain. “The first is the hypothalamus. That is the section that is primarily diseased and dysfunctional in PPID,” Faivre explained. “The hypothalamus affects the pituitary gland ‘downstream.’ That pituitary gland is what is responsible for secreting the precursors to our stress hormones. So that’s where the PPID ‘pituitary’ pars intermedia dysfunction name comes from—that abnormal function of the pituitary.”

“The typical age we diagnose PPID is around 14 years old,” said Faivre. “But, we can see up to 20% of horses 15 years old that have evidence of this disease. The incidence does increase as animals age.”

She said typical clinical signs associated with this disease include a long hair coat and loss of muscle mass, including along the topline and abdomen. “We can also see things like patchy fat deposits, abnormal sweating, increased urination and drinking, dull mentation, and an increased frequency of laminitis.”

Faivre added that many horses with PPID are predisposed to infections, such as sinus infections, tooth root abscesses, hoof abscesses, and ocular ulcers.

Veterinarians diagnose PPID with an ACTH test. “There are couple of different ACTH tests we can do,” said Faivre. “So, it is important to touch base with your vet about what the best test for your horse is. Some of these tests require a brief fast beforehand or a partial fast. So, make sure you are touching base within 24 hours of testing to ensure you are following the correct pre-test protocol.”

How to Treat PPID in Horses

Once a horse has tested positive for PPID, it is usually treated with the drug pergolide, sold under the brand name Prascend. “This drug basically helps reverse some of those changes or stabilizes some of those changes in the brain that can cause the clinical effects of PPID,” explained Faivre.

“Usually we are starting to see improvements as early as a month, but for things like the long hair coat, that can take up to several months to a year to fully resolve,” she added.

Treatment with Prascend significantly improves the horse’s quality of life and longevity. “It is something I definitely recommend treating senior horses for,” Faivre said. She recommends regularly evaluating senior horses for PPID. Horses can test negative one year and positive the next. “Repeat evaluation is very important. We can significantly improve their welfare by treating and addressing this disease.”