Heart Rhythm Problems (Arrhythmias) in Pets
An irregular heartbeat can range from harmless to life-threatening. Learn the signs, causes, and treatment options for cardiac arrhythmias in dogs and cats.
Cardiac arrhythmias are abnormal heart rhythms that can cause anything from no symptoms to sudden collapse. Some arrhythmias are benign; others require immediate treatment. RVC's cardiology team can diagnose and manage arrhythmias with ECG, echocardiography, and medication. Call +853 6677 6611.
Key Points
- Arrhythmias can be harmless or life-threatening depending on type and cause
- Common causes: heart disease, electrolyte imbalances, toxins, genetic conditions
- Symptoms include weakness, collapse, fainting, rapid breathing, or sudden death
- Diagnosis requires ECG (electrocardiogram) and often echocardiogram
- Treatment ranges from monitoring to anti-arrhythmic medications to pacemakers
- Regular monitoring is essential for pets on heart rhythm medications
Types of Arrhythmias
Common arrhythmias in pets: Sinus arrhythmia (normal variation in heart rate with breathing — harmless), premature ventricular contractions (PVCs — occasional ones are usually benign), atrial fibrillation (rapid, irregular rhythm common in large dogs with heart disease), ventricular tachycardia (rapid rhythm that can be life-threatening), and bradycardia (abnormally slow heart rate, sometimes requiring a pacemaker).
Causes and Risk Factors
Arrhythmias can be caused by underlying heart disease (dilated cardiomyopathy, mitral valve disease, hypertrophic cardiomyopathy in cats), electrolyte imbalances (potassium, calcium), toxin exposure (digoxin, certain chemotherapy drugs), hypothyroidism or hyperthyroidism, systemic disease, genetic predisposition (Boxers with arrhythmogenic right ventricular cardiomyopathy), and stress or pain.
Diagnosis and Monitoring
ECG is the primary diagnostic tool. A Holter monitor (24-48 hour portable ECG) captures intermittent arrhythmias that a brief ECG might miss. Echocardiogram (ultrasound of the heart) assesses heart structure and function. Blood tests check for electrolyte imbalances, thyroid disease, and organ function. Regular monitoring is critical for pets on anti-arrhythmic drugs.
Treatment Options
Treatment depends on the type of arrhythmia, its severity, and underlying cause. Options include: monitoring only (for benign arrhythmias), treating the underlying disease (thyroid, heart disease), anti-arrhythmic medications (sotalol, mexiletine, atenolol, diltiazem), pacemaker implantation (for severe bradycardia or heart block), and defibrillation (for life-threatening ventricular fibrillation during anesthesia or critical care).
When to See a Vet Immediately
- Fainting or collapsing episodes
- Sudden weakness or lethargy
- Rapid or irregular heartbeat felt by owner
- Exercise intolerance or difficulty breathing
- Gums that are pale, blue, or gray
- Any sudden change in behavior or activity level in a pet with known heart disease
How RVC Can Help
RVC offers advanced cardiac diagnostics including ECG, echocardiography, and Holter monitoring. If your pet has been diagnosed with an arrhythmia or shows concerning symptoms, call +853 6677 6611 for an evaluation.
This article is for educational purposes only and does not replace professional veterinary advice. If your pet is showing any symptoms, please contact Royal Veterinary Center immediately at +853 6677 6611.