An electrogardiogram, or ECG, is usually performed when an abnormal heart rhythm has been detected. As with a heart murmur, this may be an incidental finding picked up during a routine examination by your vet or may be identified during investigation for collapse or poor performance.
Many fit horses have variable rhythms at rest and it is normal for some horse to miss beats or have early beats. Very slow, fast or irregular rhythms are not normal and need further investigation.
An ECG can be performed at rest, during exercise and if necessary, for 24 hour periods. The portable ECG unit attaches to either a roller or the saddle, with leads connected to the horse's skin via sticky electrode patches. The ECG trace can be seen, via bluetooth transmission, directly on the laptop screen and is also recorded and saved for later assessment.
Left: normal ECG during exercise
Right: abnormal complexes during an exercising ECG