You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

Measuring the electrical activity in the heart is often used in veterinary medicine to help with diagnosis

The heart consists of two sides (left and right) and four chambers (2 atria and 2 ventricles) - one atrium and one ventricle on each side. For blood to be pumped into and out of the heart in an orderly way, the muscles surrounding each chamber must contract in a synchronised way. The controlled sequence of contractions of heart muscle in different chambers of the heart is governed by electrical impulses originating from a site of nervous tissue in the heart wall called the sino-atrial node or pacemaker.  

An electrocardiograph (ECG) is a machine which measures electrical changes. By comparison of the direction of movement of electrical currents across the chest between different metal plates or clips (electrodes) placed on the skin a composite electrical pattern can be derived. This produces the typical pattern associated with each heart beat - seen as a "blip" on an oscilloscope screen, or as a trace on paper.

Changes in the frequency, shape or size of this ECG trace (called an electrocardiogram) occur with a variety of heart problems and your veterinarian can tell a lot about the size of the heart and any electrical abnormalities due to disease.

If the sino-atrial node does not function properly, or there is a problem with electrical conduction through the heart, some dogs require an artificial "pacemaker" to be inserted to regularize the heart contractions. This stimulates the heart muscle by emitting regular electrical impulses generated from a battery. 

Updated October 2013