Electrocardiographic changes in the littermate mongrel dogs from birth to six months of life

Document Type: Full paper (Original article)

Authors

1 Department of Clinical Sciences, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran

2 Department of Basic Sciences, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran

3 Department of Statistics, Faculty of Mathematical and Computer Sciences, Shahid Chamran University of Ahvaz, Ahvaz, Iran

4 Graduated from Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran

Abstract

Evaluation of the cardiovascular system of canine pediatrics requires awareness of the anatomical and
physiological changes occurring from birth to six months of age. The aim of this study was to report
electrocardiographic changes in the littermate mongrel dogs from birth tosix months. Serial six-lead
electrocardiograms were recorded from ten normal littermate mongrel dogs kept on right lateral recumbency,
aged between birth and six months. Heart rate significantly decreased until the age of six months, reaching
values of 99 ± 5 beats per min. Age as well as body weight caused a gradual increase in duration of the P
wave, P-R and Q-T intervals, S-T segment and also amplitude of the R and T waves. Sinus rhythm was
commonplace in dogs under 18-week-old and sinus arrhythmia was found from 16 weeks of age. Sex only
influenced the amplitude of the R and Q waves. Males had higher mean values of the R wave amplitude
(0.991 ± 0.050) than females (0.740 ± 0.039), but females had higher mean values of the Q wave amplitude (0.256 ± 0.013) than males (0.217 ± 0.010). The mean electrical axis (±SD) of QRS waves in this study was 69.61° ± 21.47°. The possible dependence of the electrocardiographic alterations on age should be taken into consideration in practical veterinary medicinewhen working with dogs of different ages.

Keywords