ECGs are familiar to most people as the line tracing a spiky pattern across the monitor screen on medical dramas. ECGs are a record of the electrical signals in the heart as it beats that are recorded at the skin surface. Diagnostic ECG are recorded on a paper strip. They can provide information about disturbance in the heart rhythm (arrhythmias) that can be caused by disease of the heart muscle or disease elsewhere in the body that is affecting the heart. Detailed analysis of the ECG tracing can provide subtle clues to recognising enlargement of the chambers in the heart.

Normal ECG

This ECG tracing from a normal dog shows identical normal ECG complexes (beats)  The 3 different lines are recordings of the same events in different directions

 


Abnormal ECG - VPCs

This tracing shows 4 VPCs (Ventricular Premature Complexes) these can be seen as abnormal complexes that are occurring earlier than expected.  They are caused by an area of the heart muscle in the ventricle that is instigating the heart beat, rather than the normal pacemaker in the sinoatrial node.  They can be caused by wide range of problems including disease of the heart muscle (cardiomyopathy)