Short-term heart-rate variability in healthy small and medium-sized dogs over a five-minute measuring period

Abstract

Introduction: Five-minute heart-rate variability (HRV) measurement is a useful tool for assessing the autonomic nervoussystem (ANS) balance in humans, but there are no studies on healthy dogs. The aim of the study was, therefore, to provide thereference ranges in small and medium-sized breeds for short-term HRV time and frequency domain (TFD) analyses. Materialand Methods: A total of 79 healthy dogs were included in the study between 2015 and 2019. Grouping by age with thebreakpoint at six years and subgrouping by reproductive status and sex was imposed. All the dogs were included after physicaland cardiological examinations and blood analyses. The TFD of HRV were analysed from a five-minute-long digital ECGrecording after removal of non-sinus complexes. Results: There were no statistically significant differences in any TFDparameters between age, reproductive status or sex groups. A mild increase in all time domain parameters and the high-frequency(HF) band was observed in older dogs, and the low frequency (LF):HF ratio decreased in these dogs. In males, the time domainparameters and HF band increased slightly. Conclusion: The normal ranges for HRV derived from short-term ECG recording inthe usual clinical environment now have proposed reference ranges. Our findings suggest that accommodation time, age, sex, orreproductive status do not influence the results derived from these recordings, indicating that this method is reliable for assessingthe ANS function in small and medium-sized dog breeds