BACKGROUND Radiofrequency catheter ablation (RFCA) is widely used as a curative therapeutic strategy in human beings with paroxysmal supraventricular tachycardia (SVT), but rarely applied in animals. This report describes successful RFCA of atrioventricular accessory pathways (AP) in two dogs with episodic weakness caused by frequent paroxysms of supraventricular tachycardia. RESULTS Invasive electrophysiological studies (EPS) identified two APs in the 1st dog (right postero-septal, right posterior), and one in the 2nd dog (right posterior). Programmed electrical stimulation demonstrated that all APs had only retrograde unidirectional conduction, and played a role to maintain inducible atrioventricular reciprocating tachycardia (AVRT). The bypass tracts were successfully eliminated with RFCA, with consequent prevention of AVRT induction during post-ablation EPS. At 8months follow-up, the dogs were asymptomatic, and no reoccurrence of tachycardia was seen. CONCLUSIONS Concealed APs responsible for AVRT and accompanied symptoms may be safely eliminated using RFCA in dogs.