Electrocardiogram (EKG)

An EKG is ordered when a heart rhythm problem is suspected or needs to be characterized:

• Collapse, fainting (syncope), or sudden weakness episodes — especially if triggered by exercise or excitement
• An irregular heartbeat detected through a stethoscope during examination
• Monitoring known arrhythmias and the drugs used to treat them (such as sotalol, atenolol, or mexiletine)
• Evaluation in breeds at high risk for arrhythmia: Doberman Pinschers (dilated cardiomyopathy with ventricular arrhythmias), Boxers (arrhythmogenic right ventricular cardiomyopathy), and Labrador Retrievers
• Pre-anesthetic evaluation in patients with known or suspected cardiac conditions
• Suspected electrolyte abnormalities (low potassium or calcium) that affect cardiac conduction — common with urinary obstruction, Addison's disease, and certain toxins

The EKG identifies and characterizes cardiac rhythm and conduction disorders:

• Sinus arrhythmia: a normal finding in dogs (heart rate varies with breathing) — the EKG confirms this is benign
• Supraventricular arrhythmias: atrial fibrillation (common in large-breed dogs with dilated cardiomyopathy), atrial flutter, supraventricular tachycardia
• Ventricular arrhythmias: premature ventricular contractions (PVCs), ventricular tachycardia (VT) — these carry the most clinical urgency as they can degenerate into life-threatening rhythms
• Bradyarrhythmias: sick sinus syndrome, high-degree AV block — rhythms that are too slow and may require a pacemaker
• Conduction abnormalities: bundle branch blocks, which alter the shape of the waveform
• Electrolyte effects: peaked T waves from hyperkalemia (elevated potassium), classic in urethral obstruction

An EKG is performed in minutes using small electrode clips or adhesive patches placed on the skin:

• Your pet lies or stands quietly; a brief clip of fur may be needed at each contact point if the coat is thick
• Small alligator-clip electrodes or adhesive patches are placed on all four limbs and sometimes the chest
• A gel or alcohol is applied to improve electrical contact
• The EKG machine records the heart's electrical activity for 30 seconds to several minutes
• The tracings are printed or displayed digitally; our veterinarian or Dr. D'Urso reviews each waveform — rate, rhythm, intervals, and morphology — and interprets the findings

The entire recording process takes 5–10 minutes. Complex tracings or those from Holter monitors (24-hour ambulatory devices worn at home) are often sent to a cardiologist for detailed analysis.

No specific preparation is required for a standard in-clinic EKG:

• Pets can eat and drink normally before the test
• Continue cardiac medications as scheduled — the EKG is often most informative when it reflects the pet's medicated status, and the treating cardiologist will specify if a medication hold is ever needed for a particular test
• Keep your pet as calm as possible before the appointment — excitement and movement create electrical artifact that can obscure the tracing; a quiet car ride and minimal waiting-room stress help
• For Holter monitoring (24-hour EKG), the recorder is fitted at the clinic and worn at home during normal activity — detailed home instructions are provided at fitting

An in-clinic EKG is one of the least stressful diagnostic procedures we perform — no needles, no sedation, and no pain whatsoever. The electrode clips feel like small clamps on the skin; most dogs and cats are unbothered after the first few seconds. Keeping your pet still and calm during the recording improves tracing quality. Results are reviewed immediately, and our veterinarian will explain the rhythm findings, what they mean, and whether treatment, further monitoring, or specialist evaluation is recommended. For Holter monitor results, the device is returned the following day and the full 24-hour analysis is completed within a few days by a cardiologist.

An EKG is entirely passive — it only measures electrical activity; it produces no electricity and does not stimulate or alter the heart in any way. There is no radiation, no sedation required, no needle, and no contrast agent. It is safe for patients of any age, including neonates (very young animals), and for patients in active cardiac arrhythmia. The electrode clips cause no tissue damage and leave no mark. The EKG is among the safest procedures in veterinary medicine.