HRV (heart rate variability) refers to the normal variability in time intervals between consecutive heartbeats. HRV, a statistical index of the measured intervals, serves as a marker for the autonomic nervous system balance. Previously, HRV had to be measured using an ECG monitor (Holter), which is cumbersome, expensive and not intended for long-term use. The PetPace Collar is the only device that can constantly and continuously measure and report HRV. A reduction in HRV is associated with various heart diseases, sepsis, diabetes, obesity chronic pain, stress and more. Studies are ongoing to evaluate the role of HRV as a marker for additional conditions affecting pets.