PPID, formerly called equine Cushing disease, is the most common endocrine disorder in older horses and causes significant welfare harm when undiagnosed or poorly managed.
PPID causes a constellation of welfare harms that accumulate progressively in untreated or inadequately managed horses. The risk of laminitis — an exquisitely painful condition affecting the sensitive laminae of the hoof — is particularly serious, as secondary laminitis in PPID horses is a leading cause of euthanasia. Effective management with pergolide dramatically reduces laminitis risk and improves quality of life across all domains. However, the condition is significantly underdiagnosed because its symptoms — a long curly coat, drinking more water, muscle loss — are often attributed to normal aging. Veterinary education and owner awareness campaigns that promote ACTH testing in horses over 15 could prevent significant suffering by enabling earlier diagnosis and treatment before secondary complications develop.