Heart Murmurs in Dogs: When to See a Cardiology Specialist

What is a heart murmur?

• A murmur is a “whooshing” sound from turbulent blood flow

• Graded 1–6 by loudness; the grade alone doesn’t define severity but guides next steps

• Common cause in small breeds: myxomatous mitral valve disease (MMVD)

• Other causes: congenital defects, cardiomyopathies, anaemia, fever, or athletic flow murmurs

Signs to watch for

• Cough, reduced exercise tolerance, fainting/collapse, rapid or laboured breathing, restlessness at night, abdominal distension, weight loss

• Some dogs show no signs initially — early detection matters

How we investigate a murmur

• Physical exam and blood pressure

• Chest X-rays (heart size, vessels, lungs)

• Echocardiogram (ultrasound of the heart) is the gold standard to assess valves, chambers, and function

• ECG/Holter if arrhythmias suspected

• Blood tests (including pro-BNP where appropriate) to assess cardiac strain and general health

Treatment approach

• Stage-based management (e.g., ACVIM staging for MMVD)

• Medications can include pimobendan, diuretics, ACE-inhibitors, antiarrhythmics — tailored to the diagnosis

• Exercise and weight management to reduce cardiac strain

• Regular rechecks to adjust therapy

When referral helps

• Unclear diagnosis or complex/congenital disease

• Arrhythmias, syncopal events, or rapid progression

• Pre-anaesthetic cardiac assessment for higher-risk dogs

• Access to advanced cardiology imaging and interventional options