Discovering that your cat has a heart condition can be overwhelming, but understanding the disease is the most important step in managing it. Hypertrophic Cardiomyopathy (HCM) is the most common heart disease diagnosed in cats. It is widely thought to have a genetic component and can affect cats at almost any age. In cats with HCM, the heart muscle becomes abnormally thickened, which causes the heart chambers to pump blood less efficiently over time. If left unmanaged, this chronic thickening increases the risk of blood clots, abnormal heart rhythms, and congestive heart failure.

Common Signs to Watch For

Cats are exceptional at masking discomfort, and many show absolutely no symptoms until the disease has reached an advanced stage. Subtle and overt signs to watch for include:

  • Decreased activity levels and general exercise intolerance
  • An increased respiratory rate or increased breathing effort
  • A decreased appetite and progressive weight loss
  • General weakness or sudden collapse
  • Open-mouth breathing or panting (especially after minimal exertion)
  • An enlarged, fluid-distended abdomen
  • Coughing (which remains very uncommon in cats compared to dogs)
  • Sudden paralysis or severe weakness in the rear legs, accompanied by cold paw pads, due to a dislodged blood clot

Emergency Warning: Labored breathing, open-mouth breathing, collapse, or a sudden inability to use the rear legs are critical medical emergencies. If you observe any of these signs, seek immediate emergency veterinary care.

Recommended Diagnostics

To accurately stage cardiac disease and create a safe long-term management plan, we rely on targeted diagnostics:

  • Echocardiogram (Heart Ultrasound): The absolute gold standard. This non-invasive ultrasound allows us to measure heart chamber dimensions, wall thickness, and blood flow velocity. Repeated every 3 – 18 months based on cardiologist input.
  • Chest Radiographs (X-rays): Essential for evaluating the lungs and checking for early signs of fluid buildup (effusion).
  • Electrocardiogram (ECG): Recommended if irregular heart rates or arrhythmias are suspected.
  • Blood Pressure & Cardiac Biomarker Testing (NT-proBNP): To monitor physical strain on the heart muscle and check baseline organ perfusion.

Treatment Goals and Management

While there is no cure for HCM, a customized treatment plan focuses on slowing disease progression, preventing secondary complications, and maximizing comfortable quality time. General treatment goals aim to increase heart pumping efficiency, decrease systemic blood pressure, reduce fluid volume, and decrease overall oxygen demand.

Diet and Exercise Adjustments

  • Reduced Sodium Diet: High-sodium foods and treats cause fluid retention and accelerate heart failure. Transitioning your cat to a low-salt diet and avoiding salty commercial treats is recommended.
  • Omega-3 Fatty Acids (Welactin®): Provides direct nutritional and antioxidant support to support cardiac muscle cell health.
  • Restricted Exercise: Avoid hard play, running, or stressful environments that place an acute workload on the heart.

Medication Considerations

  • Anticoagulants / Blood Thinners (Clopidogrel or Aspirin): Critical daily medications that significantly reduce the risk of dangerous blood clots (thromboembolism) from forming within the enlarged heart chambers.
  • Atenolol: A beta-blocker anti-arrhythmic that helps reduce an excessively high heart rate and lower systemic blood pressure, allowing the heart chambers more time to fill efficiently.
  • Pimobendan®: A positive inotrope that increases the efficiency of heart muscle contractions while gently dilating blood vessels. (Only used under certain circumstances)
  • Furosemide: A powerful diuretic utilized if congestive heart failure develops. It forces the body to shed excess fluid from the vascular system, preventing fluid accumulation in the lungs. Unrestricted access to fresh water is vital at all times.
  • Enalapril: An ACE inhibitor that helps drop systemic vascular resistance, reducing the force the heart must push against.

Home Monitoring: The Resting Respiratory Rate

The single most important tracking tool you have at home is monitoring your cat’s resting respiratory rate (RRR) daily. This lets us establish a healthy baseline and spot early signs of a congestive crisis before it becomes a life-threatening emergency. To make this seamless, we recommend downloading the free Cardalis™ app on Apple or Google to log and track your cat’s trends.

  • How to Count: Count your cat’s breaths over one full minute while they are completely relaxed or sleeping. One breath includes both the rise and fall of the chest.

 

This blog is for informational purposes only and is not intended to provide diagnostic or treatment guidance. If you have any concerns about your pet’s health, please contact Cascade Heights Veterinary Center directly by phone at 206-403-1108,  email, or by scheduling an appointment.  Medications, supplements, and prescription diets can be conveniently ordered through our online pharmacy.