Structural heart disease affects 10% of all dogs and commonly causes heart rhythm disturbances. These arrhythmias can also occur without underlying heart disease as primary electrical disorder. In dogs referred for cardiological investigation prevalence of arrhythmias is almost 40%, adding up to potentially 52600 dogs in Belgium at risk to suffer from sudden cardiac death or the consequences of heart failure. In humans, diagnosis and treatment relies on electrophysiology studies using cardiac catheterization for destruction (or ablation) of arrhythmogenic structures in the heart. Most dogs however, are treated using drugs that lack efficacy and fail to prevent death. To date, few veterinary clinics offer electrophysiology, using conventional techniques with major limitations: 1) they expose both dog and staff to radiation, significantly increasing cancer risk, 2) only specific arrhythmia types are treatable. Hence, to prevent early death in dogs with arrhythmias, there is an urgent need for better and safer electrophysiology techniques allowing accurate diagnosis and treatment with minimal radiation. Our objectives are to validate high-resolution three-dimensional electroanatomical mapping (3D EAM) for diagnosis and treatment of canine arrhythmias. First, healthy dogs will be studied to evaluate the system’s accuracy to characterize the cardiac 3D electroanatomy. Finally, a prospective clinical trial in dogs with arrhythmias will evaluate the system for ablation procedures.