PPIDosis

PPIDosis is a term used to describe the disease process of pituitary pars intermedia dysfunction (PPID) in horses, commonly called equine Cushing's disease. The condition involves progressive changes in the pituitary gland, especially the pars intermedia, with increased secretion of proopiomelanocortin (POMC) peptides such as ACTH, contributing to metabolic and skin abnormalities.

Pathophysiology and epidemiology: In older horses, reduced dopaminergic inhibition can cause pars intermedia hyperfunction. The condition is chronic and often seen in horses over 15 years; seasonality influences ACTH levels, affecting diagnosis.

Clinical features: Typical signs include a long, untidy coat with delayed shedding, greasy skin, laminitis risk, weight and fat distribution changes, recurrent infections, and mild lethargy.

Diagnosis: Diagnosis relies on history and clinical signs plus laboratory testing. Baseline plasma ACTH is commonly measured, with seasonally appropriate reference ranges. Dynamic tests (e.g., dexamethasone suppression or TRH stimulation) are used selectively.

Management: Treatment often uses pergolide mesylate to reduce ACTH production. Management also emphasizes weight and hoof care, dental, parasite control, and monitoring for laminitis. Regular ACTH assessment helps gauge response.

Prognosis: With treatment and supportive care, many horses maintain good quality of life; PPID is typically a long-term condition requiring ongoing management.

Note: PPIDosis is not a widely used term in veterinary medicine and is largely a descriptive label for the disease process underlying PPID.