Pituitary pars intermedia dysfunction (PPID), commonly called equine Cushing's disease, is among the most prevalent endocrine disorders in older horses and ponies, with significant welfare implications if undiagnosed or poorly managed.
PPID creates a cascade of welfare harms when unrecognised or inadequately treated. The hallmark hypertrichosis causes thermal regulation difficulties, skin irritation, and social disturbance. The associated laminitis can be excruciatingly painful — horses with severe episodes may be unable to stand without support. Muscle loss reduces the horse's ability to maintain normal posture and movement. The welfare tragedy of PPID lies partly in how often it is missed: owners see a slightly odd-looking older horse rather than an animal in chronic discomfort whose life could be dramatically improved by diagnosis and medication. Regular veterinary health checks for horses over 15 years, with ACTH testing, represent a high-value welfare intervention.