EN
The aim of the study was to define the normal values for the 24-h ECG minimum, mean, and maximum heart rhythm frequency in clinically healthy dogs of different breeds and age with respect to sex and body mass, and to define what arrhythmias may occur in clinically healthy dogs. The study was conducted on 51 intact dogs of different sex, breed, and age, after taking into account their history, and performing a clinical examination, ECG, ultrasound examination, chest X-ray, and morphological and biochemical blood tests. The dogs, with their owners, were in house during the Holter monitoring. It was found that the mean 24-h heart rate frequency was 100 beats per minute, the mean maximum heart rate frequency was 210 beats per minute, and the mean minimum heart rate frequency was 43 beats per minute. Healthy dogs may manifest single premature supraventricular and ventricular beats. RR pauses lasting up to 3 s may also occur. No impact of breed, age, and sex on the analysed parameters was noted.