“BERTUS” a Rottweiler, male, 2 year old from Holland (NL) has been referred to the Electrophysiologic laboratory of Clinica Veterinaria Malpensa lead by Dr Roberto Santilli for paroxysmal supraventricular tachycardia refractory to medical treatment, to perform an endocardial mapping and possibly radiofrequency catheter ablation of the arrhythmia. During electrophysiologic study Bertus presented several episodes of atrioventricular reciprocating tachycardia mediated by a right postero-septal accessory pathway that was successfully eliminated with radiofrequency catheter ablation. After two days in ICU, Bertus has been discharged and went home in Holland without recurrence of tachycardia.