Equine Cushing's Disease (PPID): Recognition and Management in Older Horses

Pituitary pars intermedia dysfunction (PPID) is extremely common in older horses and ponies, causing progressive health deterioration and welfare consequences when unmanaged.

Key Facts

PPID affects approximately 15-30% of horses over 15 years old and over 50% of horses over 20
Classic signs include a long, curly coat that fails to shed (hypertrichosis), muscle wasting, pot belly, and laminitis
The condition results from dysfunction of the hypothalamic-pituitary axis causing excess ACTH and cortisol
Seasonal ACTH rise occurs naturally in autumn — testing requires season-adjusted reference ranges
Pergolide (Prascend) is highly effective at controlling PPID when initiated at an appropriate dose
Untreated PPID predisposes to recurrent laminitis, infections, and progressive muscle loss

Welfare Considerations

PPID causes progressive suffering in older horses through several pathways — laminitis pain, muscle weakness that makes rising difficult, immune suppression causing recurrent infections, and the discomfort of excessive coat that cannot be shed. The long curly coat is often the first visible sign, but by the time it appears, the condition has typically been present for years. Annual screening with the ACTH blood test from age 15 allows early diagnosis before clinical signs develop. Treatment with pergolide controls the condition effectively in most horses, and treated horses can remain comfortable and active for years. End-of-life decisions should be made based on welfare quality rather than age.

What You Can Do

Screen horses over 15 years annually with an ACTH blood test, adjusting for seasonal reference ranges
Learn to recognize early PPID signs including incomplete coat shedding and subtle muscle loss
Work with your veterinarian to titrate pergolide dose for optimal PPID control
Manage concurrent laminitis risk through diet control and regular farriery in PPID horses