Claire Underwood, Tiago Afonso
A wide range of pharmacological agents are used to manage arrhythmias, heart failure, and other cardiovascular conditions in horses. This chapter reviews evidence-based approaches with emphasis on practical application in equine medicine. Antiarrhythmic therapy is tailored to the underlying rhythm disturbance, using agents such as quinidine and procainamide for atrial fibrillation, lidocaine for ventricular arrhythmias, and beta-blockers for heart rate control. For heart failure, digoxin and pimobendan enhance cardiac output, while vasodilators, diuretics, and angiotensin-converting enzyme inhibitors improve hemodynamics and reduce cardiac workload. Because equine-specific data remain limited, many protocols are adapted from other species, requiring careful consideration of pharmacokinetics, dosing, and safety. Individualized treatment plans, vigilant monitoring for adverse effects, and awareness of drug interactions are essential for successful outcomes. Practical recommendations, case-based insights, and discussion of emerging therapeutic trends aim to guide clinicians in optimizing efficacy and safety in equine cardiac pharmacology.