When to Worry About a Heart Murmur in Cats
A heart murmur in cats is an unusual sound heard during a heartbeat, typically described as a "whooshing" noise in addition to the normal "lub-dub." While not always a cause for immediate concern, understanding when to worry about a heart murmur is crucial to your cat’s health and longevity.
Types of Cat Heart Murmurs
Heart murmurs can be classified based on their cause:
- Innocent/Physiologic Murmurs: Common in kittens or stressed adult cats. These murmurs are usually soft and harmless and may resolve over time.
- Pathologic Murmurs: Caused by structural abnormalities in the heart or other systemic health issues like anemia or hyperthyroidism.
Grading and Characteristics
Veterinarians grade murmurs from 1 to 6:
- Grade 1: Very soft, barely audible
- Grade 6: Extremely loud, often palpable
However, the loudness doesn't always reflect severity. Some serious conditions may cause quiet murmurs, while loud ones might be benign.
When to Be Concerned
You should become concerned if the murmur:
- Is newly detected in an adult cat
- Is accompanied by clinical signs such as:
- Lethargy or weakness
- Difficulty breathing or rapid breaths
- Poor appetite or weight loss
- Fainting, collapse, or blood clots
- Does not resolve in kittens after several months
- Occurs in breeds prone to heart disease (e.g., Maine Coon, Ragdoll)
Common Causes of Pathologic Murmurs
Pathologic murmurs may result from:
- Congenital heart defects: VSD, ASD, PDA
- Cardiomyopathies: Especially hypertrophic cardiomyopathy (HCM)
- Heart valve disorders: Insufficiencies or stenosis
- Systemic issues: High blood pressure, anemia, hyperthyroidism
- Infections: Endocarditis or heartworm disease
- Other diseases: That affect circulation or heart function
Signs of Underlying Heart Disease
Watch for:
- Weakness or fatigue
- Labored or rapid breathing
- Hiding or behavioral changes
- Pale/blue gums
- Reduced appetite or stunted growth
- Fluid accumulation or swelling
- Sudden lameness from blood clots
Diagnosis and Monitoring
Upon detecting a murmur, a vet may recommend:
- Echocardiogram: Ultrasound of the heart (most definitive test)
- Chest X-rays: To assess size and fluid presence
- Blood Tests: To check for anemia, hyperthyroidism
- ECG: To detect rhythm abnormalities
- Blood Pressure Measurements: To rule out hypertension
Treatment and Prognosis
- Innocent murmurs: No treatment required, just monitoring
- Heart disease: May require medications, dietary changes, or monitoring
- Congenital issues: Rarely, surgery is needed
Prognosis ranges from excellent (innocent murmurs) to guarded (advanced heart disease). Early detection and management can significantly improve quality of life and survival.
Takeaway for Cat Owners
Not every heart murmur is a red flag. However, combining murmur detection with thorough diagnostics is the best course of action. Stay observant for signs of illness, especially in predisposed breeds or aging cats. Regular vet checks and early action make all the difference.
