Pituitary pars intermedia dysfunction (PPID or equine Cushing’s disease) in older horses is the focus of this video with Dr. Cosette Faivre. She in an internal medicine specialist at Hagyard Equine Medical Institute in Kentucky.

Endocrine diseases 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.)

PPID in Older Horses

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

“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, loss of muscle mass, including loss of topline and abdominal musculature. “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 another thing owners see in PPID horses is an increased predisposition to infection. This can include sinus infections, tooth root abscesses, hoof abscesses, and ocular ulcers.

This disease is diagnosed 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.”

Treating PPID

Once a horse has tested positive for PPID, treatment generally involves a drug called pergolide, which is marketed as Prascend, she noted. “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 said.

Faivre said ultimately horses do significantly improve their quality of life and their longevity when they are on treatment for this disease.

“It is something I definitely recommend treating senior horses for,” stressed Faivre. She said you should evaluate senior horses for this disease even if they test negative one year, because they could test positive the next year.”Repeat evaluation is very important. We can significantly improve their welfare by treating and addressing this disease.”

PPID and the Brain

PPID is a disease of two different sections of the brain, said Faivre. “The first is the hypothalamus. That is the section that is primarily diseased and dysfunctional in PPID,” she 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.”

Further Reading