Heart Disease in Dogs
Dogs commonly develop heart disease, especially as they age.
If your dog has a heart murmur but shows no clinical signs of heart dysfunction, we may not recommend immediate treatment. However, we advise you to monitor your pet at home and bring them in for a yearly examination, typically during their vaccination and health check.
Heart Murmur Grading
Dogs with heart murmurs will have their murmur graded by your veterinarian at each visit on a scale from 1 to 6. Once the murmur reaches a grade 3, we recommend taking a chest X-ray to check for any signs of cardiac remodeling.
What to Monitor in a Healthy Pet with a Heart Murmur
- Resting Heart Rate
Measure the number of heartbeats per minute (bpm). This rate varies depending on the dog’s size, but most dogs will have a resting heart rate between 60 and 100 bpm. Any increases over time may indicate a concern worth discussing with your veterinarian. - Resting Respiratory Rate
Count the breaths per minute when your dog is resting or asleep. A normal resting respiratory rate (RR) is between 16 and 24 breaths per minute. A rate above 30 or noticeable effort in breathing could signal a problem.
Get resting respiratory rate app from Apple store
Get resting respiratory rate app from Google Play store
- Exercise Tolerance
Notice if your dog can’t walk as far as they used to. A reduction in exercise tolerance may be due to heart disease rather than just age.
When the Heart Begins to Fail
The heart functions as a pump. When it begins to pump inefficiently, the body activates mechanisms to maintain oxygenated blood flow. This includes retaining fluid, increasing blood pressure, raising the heart and respiratory rates, and reducing exercise. When these compensatory mechanisms are overwhelmed, heart failure can occur, either gradually (chronic) or suddenly (acute).
Common Types of Heart Disease
The most frequent heart disease in dogs is mitral valve insufficiency, where a heart valve starts to leak, progressively worsening with age.
Heart Medication and Your Dog
If your dog’s heart isn’t functioning well, your veterinarian can prescribe medications to help them live a happier, healthier life. A range of medications may be prescribed, and doses should be adjusted during regular monitoring visits, which may include blood tests and X-rays.
Medications can:
- Increase the strength of the heartbeat
- Control blood pressure
- Manage fluid retention
- Prevent kidney complications from overcompensation
Monitoring Your Dog with Heart Disease
Dogs respond best to treatment when closely monitored. At Pittwater Animal Hospital, we recommend examining your dog every 3-6 months if they’re on heart medication.
We also advise twice-yearly comprehensive blood tests. These can be completed through our discounted medication review system, where reminders are sent to your phone, and consultations and tests are offered at a reduced rate. Urine tests may also be performed if needed.
Chest X-rays for Monitoring
Chest X-rays can assess your dog’s Vertebral Heart Score (VHS), which measures heart size and is an excellent monitoring tool. A normal VHS ranges from 8.7 to 10.7, but monitoring changes in your dog’s individual score is most important. Enlarged hearts become more inefficient as disease progresses, especially without proper medication. Chest X-rays can also detect congestion in the lungs, indicating a worsening condition.
Types of Heart Disease in Dogs
While valve failure is the most common, we also encounter:
- Heartworm Disease (more common in Queensland)
- Cardiomyopathy (weak heart muscle)
- Arrhythmia (heart rhythm disturbances)
- Endocarditis (heart valve infection)
- Pericardial Effusion (fluid buildup in the sac around the heart)
These less common conditions may require consultation with a veterinary specialist. If we refer your pet, the specialist will assess the condition and coordinate with us to create the best treatment plan. Many rechecks can be done at Pittwater, so your dog can be monitored locally.
Caring for an Unwell or Elderly Pet
Additional advice on how to care for an elderly or unwell pet is available. Please don’t hesitate to ask us for guidance.
