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Heart Murmur in Dogs and Cats: What Does It Mean and When to Pay Attention?

  • Aug 6
  • 3 min read
vet examining a dog

Have you noticed that your four-legged companion gets tired faster during walks, rests more frequently, or even coughs for no apparent reason? One of the most common causes of these subtle changes can be a cardiovascular issue. A heart murmur in dogs and cats is often the first warning sign detected by a veterinarian during a routine stethoscope examination.


What exactly does this finding mean, what are its causes, and how should you proceed to ensure your pet lives a long and happy life?


What Is a Heart Murmur, Exactly?


The heart functions as a powerful pump that we perceive as regular, clear beats. However, if the blood flow within the heart becomes turbulent—for example, due to a poorly closing valve or a narrowed vessel—an acoustic phenomenon is created, which we hear as a murmur.


Murmurs are graded on an intensity scale from 1 to 6. While grade 1 is barely perceptible, grade 6 can be heard even when holding the stethoscope just slightly off the chest. However, the loudness of the murmur does not always directly correlate with the severity of the disease—a detailed diagnosis is always key.


What Are the Most Common Causes?

Causes vary not only by species, but also by age and breed:


In Dogs


  • Degenerative Valve Disease (Endocardiosis): Primarily affects older dogs of small and medium breeds (e.g., Cavalier King Charles Spaniel, Dachshund, Poodle). The valves lose elasticity and fail to close properly.

  • Dilated Cardiomyopathy (DCM): More commonly affects large and giant breeds (Doberman, Great Dane, Boxer). It involves thinning of the heart muscle wall and enlargement of the heart chambers.

  • Congenital Defects: Often found in puppies (e.g., Patent Ductus Arteriosus – PDA).


In Cats


  • Hypertrophic Cardiomyopathy (HCM): The most common heart disease in cats, characterized by an abnormal thickening of the heart muscle. It frequently affects breeds such as the Maine Coon, Ragdoll, or British Shorthair, but can also occur in domestic shorthair cats.


Symptoms You Shouldn't Ignore


In the early stages, your pet may show no symptoms at all. However, as the condition progresses, you might notice:

  • Rapid fatigue during normal exercise or play

  • A heart murmur in dogs is often accompanied in advanced stages by a night or morning cough (as an enlarged heart presses against the trachea)

  • Rapid or labored breathing (even at rest)

  • Blueish tint to the tongue or gums during exertion

  • Sudden weakness, collapse, or fainting

  • In cats, uncharacteristic lethargy or sudden paralysis in the hind legs (due to thromboembolism)


How Are Diagnosis and Treatment Handled?


If you suspect a heart problem, do not hesitate to contact a professional. The initial step is a physical exam using auscultation (listening with a stethoscope), usually followed by:

  1. Echocardiography (Heart Ultrasound): Displays the heart's structure, valve movement, and blood flow in real time.

  2. Chest X-ray: Reveals potential heart enlargement or fluid accumulation in the lungs.

  3. ECG and Blood Pressure Monitoring.

With modern medication, heart failure can be managed very effectively, slowing its progression and ensuring a high quality of life for your pet for years to come. Early detection is crucial.


Save Your Pet the StressTraveling to a clinic and waiting in a room full of unfamiliar scents and animals creates unnecessary stress for a cardiac patient. Our fully equipped Sonda.cz mobile veterinary clinic comes right to your doorstep. The veterinarian examines your dog or cat in peace right inside the van, which functions as a full-fledged clinic on wheels.

When to Call the Vet?


If you notice changes in your pet's breathing or a reduced willingness to exercise, don't wait for a routine check-up. Learn more about how our veterinary care at home works.

Timely diagnosis can give your pet years of happy life!


You can book a remote phone consultation here.


You can book a veterinary home visit here.


You can request a veterinary ambulance (for acute cases) here.


You can book an appointment at our clinic in Prague 2 here.


You can go back to the full list of articles here, or to the homepage here.


Note: All information provided on this website is for educational purposes only. None of the information here is intended to replace a medical diagnosis and should not be considered medical advice or a recommended treatment.

* Image source: Google Gemini


 
 
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