Pituitary Pars Intermedia Dysfunction (PPID), commonly called equine Cushing's disease, is the most common endocrine disorder in aged horses and ponies. It causes progressive hormonal dysregulation that significantly impairs welfare through laminitis, muscle wasting, and immune compromise.
PPID causes progressive, multi-system welfare harm: the characteristic hypertrichosis (abnormal coat) causes heat stress in summer and skin problems; muscle wasting leaves horses weak and prone to injury; immune compromise allows parasite burdens that cause further suffering; and most significantly, PPID-associated insulin dysregulation triggers recurrent laminitis — potentially the most painful consequence. Owners frequently attribute early PPID signs to normal ageing, delaying diagnosis and treatment. The welfare opportunity is significant: pergolide is effective, relatively inexpensive, and well-tolerated by most horses — it can largely reverse clinical signs and prevent the laminitic complications that cause the most severe welfare harm. Annual ACTH monitoring in horses over 15 and prompt treatment initiation are the key welfare interventions.