Horse Cushing Disease vs EMS Distinction

Distinguishing between pituitary pars intermedia dysfunction (PPID) and equine metabolic syndrome (EMS) is essential for correct welfare management as their causes and primary treatments differ.

Key Facts

PPID (equine Cushing's) is caused by pituitary adenoma producing excess ACTH; EMS by insulin dysregulation
Both conditions predispose horses to laminitis but through different mechanisms
PPID typically affects horses over 15 years; EMS commonly affects younger, easy-keeping breeds
ACTH blood testing diagnoses PPID; dynamic insulin testing diagnoses EMS
Pergolide treats PPID by reducing excess dopamine signaling; there is no equivalent medical treatment for EMS
Some horses have both conditions simultaneously, complicating management
Low sugar and starch dietary management benefits both conditions and is appropriate for all metabolic horses

Welfare Considerations

Confusing PPID and EMS leads to incorrect treatment that fails to address the primary welfare risk - laminitis. A horse with EMS treated with pergolide (the PPID treatment) will not have its insulin dysregulation addressed and remains at laminitis risk. Conversely, a horse with PPID diagnosed as EMS may not receive the pergolide that could dramatically improve their hormonal control and overall quality of life. Correct diagnostic testing is essential to guide appropriate treatment. Both conditions cause welfare harm primarily through laminitis risk, but their management differs sufficiently that accurate distinction is a genuine welfare requirement.

What You Can Do

Have metabolically affected horses tested for both conditions with appropriate, specific tests
Do not assume that dietary management alone is sufficient for PPID horses - test for PPID and add pergolide if positive
Repeat testing annually as PPID can develop in horses previously diagnosed with EMS only
Work with an equine internal medicine specialist for complex cases with both conditions
Monitor both conditions through regular ACTH and insulin testing to guide dose adjustments
Implement low sugar and starch diet as the universal dietary foundation for all metabolic horses