Heart Disease in Dogs
Heart disease is common in dogs, especially as they age. Some dogs live for years without showing symptoms, while others may need medication and monitoring to maintain their quality of life.
Grading Heart Murmurs
Heart murmurs are graded from 1 to 6:
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Grade 1–2 — usually mild and may need only monitoring.
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Grade 3 or higher — we recommend a chest X-ray to assess heart size (vertebral heart score) and lung health.
If Your Dog Has a Heart Murmur
If your dog is diagnosed with a heart murmur but has no other signs of illness, we may not start treatment right away. Instead, we recommend:
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Annual check-ups — usually done at vaccination time.
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Chest X-ray once the murmur reaches Grade 3 — to look for signs of heart enlargement or changes in lung health.
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Home monitoring — keeping track of heart rate, breathing rate, and exercise tolerance.
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Resting Heart Rate — Most dogs have 60–100 beats per minute. An increase over time may signal trouble.
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Resting Respiratory Rate (RRR) — Count breaths while your dog is asleep. Normal is 16–24 per minute. Above 30, or any signs of effort, should be discussed with your vet.
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Get resting respiratory rate app from Apple store
Get resting respiratory rate app from Google Play store
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Exercise tolerance — Notice if your dog tires sooner than before.
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When the Heart Starts to Struggle
If the heart can’t pump efficiently, the body compensates by:
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Retaining fluid
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Increasing heart and breathing rates
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Raising blood pressure
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Limiting activity
When these compensations fail, heart failure can occur gradually or suddenly.
Common Heart Conditions
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Mitral valve insufficiency — the most common cause in older dogs
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Heartworm disease (rare in Sydney, more common in northern Australia)
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Dilated cardiomyopathy (weak heart muscle)
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Arrhythmias (abnormal rhythm)
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Endocarditis (heart valve infection)
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Pericardial effusion (fluid around the heart)
Medication & Ongoing Care
Medications can:
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Strengthen heart contractions
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Control blood pressure
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Reduce fluid retention
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Protect the kidneys
Dogs on heart medication should be examined every 3–6 months. We also recommend:
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Blood and urine tests twice yearly (discounted through our Medication Review system)
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Chest X-rays to monitor Vertebral Heart Score (VHS) — tracking changes over time is more important than one single reading
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X-rays can also detect fluid in the lungs
Specialist Referral
If your dog’s condition is unusual or advanced, we may refer you to a veterinary specialist. Ongoing checks can often be done back at Pittwater Animal Hospital for convenience.
Caring for Older or Unwell Dogs
We can also help you with supportive care strategies, diet advice, and comfort measures for elderly or fragile pets.
Make an Appointment with the Vet →
Call us on 9913 7979
Or message us through the website or email reception@pittvets.au
