When to Worry About a Heart Murmur in Cats
A heart murmur is an unusual sound heard during the heartbeat cycle, typically detected by a veterinarian using a stethoscope. This sound, often described as a “whooshing” noise, results from turbulent blood flow within the heart or blood vessels. While a murmur may indicate an underlying heart condition, it can also be completely harmless. Knowing when to worry is crucial for maintaining your cat’s health.
Types of Heart Murmurs
- Innocent or physiologic murmurs: Usually found in young kittens or stressed adult cats. These are soft, temporary, and not caused by underlying disease.
- Pathologic murmurs: Caused by structural abnormalities in the heart or external issues like anemia or hyperthyroidism. These require further examination.
Grades and Characteristics
Heart murmurs are graded on a scale of 1 to 6, with 1 being very faint and 6 extremely loud. The severity of the murmur doesn’t always reflect the seriousness of the heart condition:
- Grade 1: Barely audible
- Grade 2–3: Clearly heard but not loud
- Grade 4–6: Loud; may be felt as a vibration through the chest wall
Configuration (timing within the heart cycle) and location also help determine its cause. A murmur heard loudest over specific regions can indicate different heart defects or conditions.
Common Pathologic Causes
- Congenital defects: Such as ventricular septal defect (VSD), atrial septal defect (ASD), or patent ductus arteriosus (PDA)
- Cardiomyopathy: Especially hypertrophic cardiomyopathy (HCM), the most prevalent heart disease in cats
- Valve diseases: Insufficiencies or narrowing (stenosis)
- High blood pressure: Systemic hypertension
- Anemia or hyperthyroidism
- Heartworm disease
- Endocarditis: Infection of heart valves
- Systemic diseases: Affecting blood viscosity or flow
Some breeds are genetically predisposed to heart issues, including:
- Maine Coons
- Ragdolls
- British and American Shorthairs
- Siamese
Signs of Concern
Unfortunately, cats often show no symptoms until a disease advances. However, if your cat displays any of the following, a heart murmur may be cause for concern:
- Weakness or lethargy
- Reduced activity or exercise intolerance
- Labored/rapid breathing or panting
- Poor appetite and weight loss
- Isolation or hiding
- Pale or bluish gums
- Fainting episodes
- Swelling/fluid in lungs or abdomen
- Sudden hind limb paralysis: Suggestive of thromboembolism
- Stunted growth: In kittens with severe defects
Diagnostic Methods
If a murmur is detected during a routine check-up, your vet may recommend several tests to determine the significance:
- Echocardiogram: A detailed ultrasound of the heart—gold standard for diagnosis
- Chest X-rays: Assess heart size and fluid in lungs
- Blood tests: Rule out causes like anemia or hyperthyroidism
- Electrocardiogram (ECG): Detects rhythm abnormalities
- Blood pressure measurement
Treatment Approaches
Whether or not treatment is necessary depends on the underlying cause:
- Innocent murmurs: Often require no treatment, just regular monitoring
- Heart disease: May involve medications such as diuretics or cardiac drugs
- Secondary conditions: Managing blood pressure and thyroid levels
- Monitoring: Periodic imaging or blood tests
- Surgical intervention: Rare, used for some congenital defects
- Stress reduction and proper nutrition
Prognosis and Outlook
The outlook varies:
- Innocent murmurs: Excellent prognosis; most kittens outgrow them
- Mild heart disease: Good prognosis with management
- Severe heart conditions: Prognosis may be guarded to poor
Preventive Tips
- Schedule regular veterinary checkups
- Monitor for changes in behavior, breathing, or appetite
- Consult your vet promptly if symptoms occur
Early detection and proactive care can greatly improve your cat’s quality and length of life, even with a significant heart issue.
