Hearing that your dog or cat has a heart murmur can be alarming. Many pet owners immediately worry that their beloved companion is in heart failure or that something serious is wrong. The good news is that a heart murmur is not a diagnosis—it is simply a sound your veterinarian hears when listening to the heart that suggests blood flow is turbulent.

Some murmurs are associated with significant heart disease, while others may never cause problems. The next step is understanding what the murmur means for your individual pet.

How Common Is Heart Failure in Pets with Heart Murmurs?

Not every pet with a heart murmur will develop congestive heart failure (CHF).

In dogs:

  • Heart murmurs are commonly caused by degenerative mitral valve disease, particularly in small and senior breeds.
  • Many dogs with valve disease will eventually progress over time, but some remain stable for years without developing heart failure.

In cats:

  • Heart murmurs can occur with heart disease such as hypertrophic cardiomyopathy (HCM).
  • They can also be present in completely healthy cats.
  • Some cats with significant heart disease may not even have a murmur.
  • Others with loud murmurs may never experience clinical signs.

Because the presence or loudness of a murmur alone cannot predict whether a pet will develop congestive heart failure, further evaluation is often recommended.

Monitoring at Home: Resting Respiration Rate

One of the most valuable things pet owners can do at home is monitor their pet’s resting respiration rate (RRR).

Changes in breathing rate are often one of the earliest indicators that heart disease may be progressing toward congestive heart failure.

We recommend recording your pet’s resting respiration rate daily while sleeping or resting comfortably.

The easiest method is to use the Cardalis App (available for Apple and Android devices), which allows you to:

  • Measure your pet’s breathing rate
  • Track trends over time
  • Email results directly to your veterinary team

Alternatively, you can manually count how many breaths your pet takes over one minute.

When Should You Call?

Please contact Cascade Heights Veterinary Center if your pet’s sleeping breathing rate is:

  • Greater than 30 breaths per minute: Call the clinic for advice and evaluation.
  • Greater than 40 breaths per minute: If we are closed, contact a 24-hour emergency veterinary hospital to discuss next steps.

Why Staging Heart Disease Matters

One of the most important reasons to perform an echocardiogram is to determine the current stage of your pet’s heart disease.

For dogs with certain forms of heart disease, starting medication at the appropriate time can make a meaningful difference. Studies have shown that initiating heart medications in the correct stage of disease can:

  • Delay the onset of congestive heart failure by approximately 15 months
  • Extend survival by approximately 6 months after heart failure develops

An echocardiogram provides the most accurate assessment of disease stage. If an echocardiogram is not possible, chest radiographs (x-rays) can provide helpful information and guide treatment decisions.

Why We Recommend an Echocardiogram

The best way to determine whether a heart murmur is associated with heart disease—and how advanced that disease may be—is with an echocardiogram.

Echocardiogram

An echocardiogram is a non-invasive ultrasound of the heart used to assess its structure and function. This diagnostic tool helps us better understand your pet’s cardiac health and determine whether treatment or monitoring is needed.

At Cascade Heights Veterinary Center, we partner with mobile veterinary cardiologists. Dr. Maran and Dr. Woodfield visit our clinic every three to four weeks, performing echocardiograms on-site and providing our doctors with a detailed formal report. In most cases, sedation is not required.

If you prefer a direct consultation with a cardiologist, referrals are also available through:

  • Olympic Veterinary Cardiology
  • Summit Veterinary Referral Center
  • Veterinary Specialty Center (Lynnwood)
  • Portland Veterinary Cardiology (Portland)

If you’d like to schedule an echocardiogram through Cascade Heights, please let us know and we’ll coordinate the next available appointment.

What Signs Should I Watch For?

  • Increased respiratory effort
  • Persistent coughing (especially in dogs)
  • Exercise intolerance
  • Fatigue or weakness
  • Decreased appetite
  • Fainting episodes
  • Distended abdomen
  • Difficulty breathing

If any of these signs develop, veterinary evaluation is recommended promptly.

The Bottom Line

A heart murmur is a finding—not a diagnosis. While some pets with heart murmurs may eventually develop congestive heart failure, many live comfortably for years with little or no progression of disease.

The key is understanding exactly what is causing the murmur and monitoring for changes over time.

An echocardiogram provides the most accurate information about your pet’s heart health and allows us to make informed recommendations about treatment and long-term care.

If your pet has recently been diagnosed with a heart murmur, our team at Cascade Heights Veterinary Center is here to help guide you through the next steps and create a monitoring plan tailored to your pet’s needs.