CONTINUOUS MONITORING OF ECG IN HORSES AT REST AND DURING EXERCISE

A method for the continuous monitoring of the electrocardiogram (ECG) of horses at rest and during exercise was evaluated in five healthy ho rses. The horses spent 24 hours in a loose box and performed a standar dised exercise test on a treadmill during this period. Two bipolar lea ds were recorded, lead 1 between the xiphoid and the left withers, and lead 2 between the left ventral thorax and the left dorsal thorax, us ing disposable electrodes. The quality of the ECGs enabled both an 'op erator-controlled' and an automatic analysis to be made. Lead 1 was th e most stable during exercise and lead 2 during rest in the loose box. The heart rate and occurrence of arrhythmias were assessed over 22 ho urs. During the boxed period the heart rate varied from 31 +/- 2 to 13 8 +/- 11 beats per minute (bpm) and during exercise it varied from 79 +/- 8 to 177 +/- 12 bpm. All the horses had sinus arrhythmias, sinus t achycardias and second degree atrioventricular blocks. One horse devel oped a ventricular escape rhythm.