Aim: The present investigation was intended to generate some basic data on electrocardiography (ECG) parameters in different breeds and their alterations in respect to sex and age.

Materials and Methods: The present investigation was carried out on 239 owned dogs of 11 different breeds presented to the Institute Veterinary Clinic during 2018-2019. The animals, irrespective of breed and sex were grouped on the basis of their age groups. Recordings of ECG were performed by a single-channel ECG machine (CardiartR, BPL, India) at 25 mm/s paper speed and 10 mm=1 mV calibration keeping the animals on the right lateral recumbence without any anesthesia. Heart rate, along with the amplitude and duration of different waves and complexes was measured.

Results: Heart rate did not vary significantly among breeds, sex, and different age groups. The highest heart rate has been reported in Doberman and the lowest in Beagle. The heart rate was lowest at the age group of 6 months-2.5 years and highest around 10.5-12.5 years irrespective of breed and sex. The incidence of sinus arrhythmia was mostly seen in older dogs. All the waves and complexes did not vary significantly between breeds, age, and sex except P duration which was significantly (p<0.05) higher in Golden retriever and Doberman breeds.

Conclusion: The present investigation generated some reference values of ECG in dogs which will help the clinicians to diagnose different cardiac abnormalities through ECG.

Keywords: dogs, electrocardiogram, heart rate, rhythm.