Drugs Acting on the Urinary System

Pharmacologic interventions are critical for managing renal dysfunction, oliguria, polyuria, urine retention, and urolithiasis in horses. This chapter provides a review of evidence-based strategies for drug selection and practical considerations in clinical applications. Diuretics – including loop, thiazide, osmotic, carbonic anhydrase inhibitors, and potassium-sparing agents – remain central for addressing fluid overload, acute kidney injury, and exercise-induced pulmonary hemorrhage. Furosemide continues to be the primary loop diuretic, while there is limited evidence supporting mannitol and dopamine use. Potassium-sparing agents and autonomic drugs are reserved for refractory cases of urine retention and incontinence. Emphasis is placed on culture-based antimicrobial selection for urinary tract infections to ensure targeted and effective therapy. Individualized treatment plans, monitoring for adverse effects, and integration of pharmacologic principles into clinical decision-making are highlighted throughout. Additionally, emerging research on novel diuretic agents, dosing strategies, and case-based insights aims to refine therapeutic approaches and improve clinical outcomes in equine practice.