Cardiac arrhythmias can cause hypoxia, hypotension, disturbance in tissue blood supply and cardiac arrest. Diagnosis of cardiac arrhythmias using electrocardiography is simple and common. The purpose of this study was to review the prevalence of cardiac arrhythmias in dogs brought to the Veterinary Clinic for different reasons. One hundred and seventy six dogs of different age groups (<1, 1-3, 3-5, 5-6, >6 years), and both sexes were included in this study. The survey was carried out for two years. Electrocardiogram of each dog using standard limb leads (I, II, and III) and augmented limb leads (aVR, aVL, and aVF) were taken and investigated for rhythm irregularities. Results obtained from 1232 traces indicated sinus arrhythmia (27.9%), sinus tachycardia (7.8%), wandering pacemaker (5.1%), ventricular premature beats (3.4%), atrioventricular block type II (1.2%), and the dogs simultaneously showed two kinds of disrhythmias (11.9%). From 176 dogs, 68 were males (56.6% ) and 33 females (58.9%) showed different types of arrhythmias. Results of this study indicated that in spite of referring the dogs merely for check up and vaccination, have cardiac arrhythmia that some of which could be dangerous for animal life.