Pituitary pars intermedia dysfunction (PPID) in horses requires long-term treatment. The disease can be worrisome and costly to owners over time. While PPID, also known as Cushing’s disease, usually affects senior horses, it can also affect horses as young as 15 years old.

Owners can take heart from a research presentation made at the the 5th Global Equine Endocrine Symposium (GEES), brought to you by Boehringer Ingelheim, in 2023. Hal Schott, DVM, PhD, DACVIM, of Michigan State University, presented the paper, “Long-Term Response of Equids with Pituitary Pars Intermedia Dysfunction to Treatment with Pergolide.”

Research on PPID Long-Term Treatment in Horses

Schott shared that long-term (> 5 years) treatment of PPID equids with pergolide produces clinical improvement in nearly all affected animals. He found normalization of endocrine test results in > 60% of cases and high owner satisfaction.

Schott said PPID is being increasingly recognized and treated. However, there is limited data on long-term response to treatment with pergolide.

Clinical Improvement

This study determined that long-term treatment of equids with PPID produced clinical improvement in nearly all affected animals.

After 2.5 years of treatment, all owners reported clinical improvement. Endocrine test results were normal in 79% of equids.

After 5.5 years, owners of 13 surviving equids reported continued clinical improvement. Seventy-five percent of horses had normal endocrine test results.

After 9.5 years of treatment, only two of six surviving equids had normal endocrine test results.

Seven out of 15 equids during the study had undergone a dosage increase to 4 μg/kg, PO, q24h (maximum study dose) from 1.7 to 4.7 years of the study. However, this research found horses might not need progressively increasing drug doses.

Medical problems documented over the course of the study included gastrointestinal disturbances (colic, diarrhea), loss of body condition (attributed to dentition and aging), laminitis, arthritis, and worsening of hypertrichosis (long hair coat that doesn’t shed properly).

Of interest, a decrease in appetite (the most common adverse effect reported in the open field clinical efficacy study) was reported for only three (10%) of the equids in the extended use study.

Endocrine test results can improve in PPID horses treated with pergolide over a prolonged period. Schott found that treatment with pergolide improves equine quality of life, but it does not prolong life.

Schott said that overall, there is high client satisfaction with extended use of
Prascend® (pergolide tablets).

Editor’s note: You can access the full Proceedings of the 5th GEES Symposium here.

Further Reading

  • Kimberly S. Brown
    Kimberly S. Brown is an award-winning writer and publisher. She is the Editorial Director for My Senior Horse. Brown spent 10 years at Equine Network, parent company of My Senior Horse. Prior to that she worked for three years in equine nutrition after she retired from nearly 30 years working at The Blood-Horse. Brown spent the last 15 years of her time at that organization creating and developing The Horse and TheHorse.com.
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