Electrocardiogram (EKG) - Veterinary Cardiology Services - Roanoke, VAAn EKG records the electrical activity of the heart by attaching small contact electrodes to the animal’s limbs and chest wall. An EKG is commonly used and recorded during anesthesia; however, a veterinarian may also recommend an EKG for diagnosis of abnormal heart rhythms and also can be useful for identification of heart enlargement or drug effects on the heart.