Heart Murmurs in Cats: Causes, Diagnosis & Management

Understanding Heart Murmurs in Cats

Heart murmurs in cats represent an abnormal heart sound detected during veterinary examination. These sounds occur when blood flows turbulently through the heart chambers, often indicating an underlying cardiac condition that requires attention. While some heart murmurs may be harmless, others can signal serious heart disease that needs prompt veterinary intervention.

Feline heart murmurs vary in severity and clinical significance. Understanding the nature of these murmurs and their potential implications for your cat’s health is essential for proper management and care. This comprehensive guide explores everything cat owners need to know about heart murmurs, from diagnosis to treatment and long-term management.

What Causes Heart Murmurs in Cats?

Heart murmurs in cats can stem from various sources, ranging from benign physiological conditions to serious structural heart abnormalities. Identifying the underlying cause is crucial for determining appropriate treatment and management strategies.

Congenital Heart Defects

Some cats are born with structural abnormalities in their hearts that can cause murmurs from birth. These congenital defects include:

• Ventricular septal defects (holes in the wall separating heart chambers)
• Patent ductus arteriosus (PDA) – failure of a fetal blood vessel to close after birth
• Valve malformations that prevent proper closure

Acquired Heart Disease

More commonly, heart murmurs develop later in a cat’s life due to acquired conditions such as:

• Hypertrophic cardiomyopathy (HCM) – thickening of the heart muscle, particularly common in cats
• Dilated cardiomyopathy (DCM) – enlargement and weakening of the heart chambers
• Valve disease – deterioration of heart valves with age
• Hyperthyroidism – causing secondary heart changes due to increased metabolic demands

Functional or Innocent Murmurs

Not all murmurs indicate heart disease. Functional or innocent murmurs can occur due to:

• High cardiac output states (excitement, stress, or fever)
• Anemia – when blood is thinner, flow becomes more turbulent
• Temporary conditions that resolve without treatment

Grading and Classification of Heart Murmurs

Veterinarians classify heart murmurs using a standardized grading system based on intensity. This helps track progression and determine clinical significance.

Murmurs are further classified by timing (systolic, diastolic, or continuous), location on the chest where they’re best heard, and quality of sound (harsh, musical, etc.). These classifications help veterinarians narrow down potential causes.

Symptoms Associated with Heart Murmurs

Many cats with heart murmurs show no outward signs, especially in early stages. However, as underlying heart disease progresses, cats may exhibit symptoms including:

• Lethargy and decreased activity
• Poor appetite and weight loss
• Increased respiratory rate or effort
• Coughing (less common in cats than dogs)
• Exercise intolerance
• Fainting or collapse
• Pale or bluish gums
• Abdominal distension due to fluid accumulation

In severe cases, cats may develop congestive heart failure (CHF), characterized by fluid buildup in or around the lungs (pulmonary edema or pleural effusion), making breathing difficult. This represents a medical emergency requiring immediate veterinary care.

Diagnosing Heart Murmurs in Cats

Proper diagnosis of heart murmurs involves several steps to determine the underlying cause and clinical significance.

Veterinary Examination

The diagnostic journey begins with a thorough physical examination. Your veterinarian will perform a comprehensive assessment, checking your cat from nose to tail while looking for abnormalities such as thyroid enlargement, weight loss, rapid breathing, or abdominal distension. Using a stethoscope, they’ll listen carefully to your cat’s heart, noting any abnormal sounds, rate, and rhythm while also feeling the pulse. Additionally, they’ll examine the chest for signs of fluid retention that could indicate advancing heart disease.

Diagnostic Tests

When a heart murmur reaches grade 3 or higher, or is causing observable symptoms, further investigation is typically recommended. Common diagnostic procedures include:

• Chest X-rays: Performed under sedation or anesthesia to assess heart size and position, lung condition, and the status of major blood vessels.
• Echocardiogram: An ultrasound scan of the heart that visualizes blood flow direction and heart structure, often requiring referral to a veterinary cardiologist.
• Electrocardiogram (ECG): Records the heart’s electrical activity to identify arrhythmias or other electrical abnormalities.
• Blood tests: Measures cardiac biomarkers like Troponin and NT-pro BNP that may indicate heart muscle damage or strain.
• Blood pressure measurement: Typically using a cuff and Doppler ultrasound, with readings above 180mmHg systolic considered elevated even accounting for stress-induced increases.

These diagnostic tools help veterinarians determine whether the murmur represents a benign condition or serious heart disease requiring treatment.

Treatment Options for Heart Murmurs

It’s important to understand that heart murmurs themselves don’t require treatment – rather, the underlying condition causing the murmur is what needs addressing. Treatment approaches vary widely based on the diagnosis, severity, and your cat’s overall health status.

Benign Murmurs

Functional or innocent heart murmurs generally require no treatment at all. Your veterinarian may recommend periodic monitoring to ensure the condition remains stable.

Congenital Defects

Some congenital heart issues may resolve naturally as your cat grows. Small septal defects (holes in heart walls) can sometimes close on their own within the first six months of life. However, more significant defects like patent ductus arteriosus (PDA) may require surgical intervention to correct the abnormality.

Acquired Heart Disease

Treatment for acquired heart conditions focuses on managing symptoms and slowing disease progression:

• Medications: Depending on the specific condition, your veterinarian may prescribe medications such as:
  • ACE inhibitors (like benazepril) to reduce strain on the heart
  • Diuretics (like furosemide) to reduce fluid buildup
  • Beta-blockers to control heart rate
  • Calcium channel blockers to improve heart function
• Dietary management: Low-sodium diets may be recommended for cats with congestive heart failure
• Treatment of underlying conditions: Addressing primary issues like hyperthyroidism or anemia may help improve cardiac function

Congestive Heart Failure

For cats experiencing congestive heart failure, more intensive intervention is needed:

• Hospitalization for stabilization
• Oxygen therapy to support breathing
• Thoracocentesis – a procedure to remove fluid from around the lungs (pleural effusion)
• Combination medication therapy

Treatment decisions often consider factors beyond the heart condition itself, including the cat’s age, overall health status, and practical considerations such as medication costs and administration challenges.

Long-term Management and Prognosis

Ongoing management of cats with heart murmurs requires a collaborative approach between pet owners and veterinary professionals.

Monitoring and Follow-up Care

Regular veterinary checkups are essential for cats with heart murmurs, with frequency depending on the severity of the underlying condition. These appointments typically include:

• Physical examinations to assess overall condition
• Auscultation to monitor murmur intensity and heart function
• Periodic diagnostic tests (blood work, X-rays, echocardiograms) to track disease progression
• Medication adjustments as needed

Home Care

At home, cat owners play a vital role in monitoring their pet’s condition:

• Tracking respiratory rate and effort
• Monitoring activity level and appetite
• Administering medications as prescribed
• Maintaining appropriate diet and weight
• Reducing environmental stressors

Prognosis

The long-term outlook for cats with heart murmurs varies dramatically depending on the underlying cause. Prognosis ranges from excellent for benign murmurs to guarded or poor for severe congenital or acquired heart disease. Rather than focusing on cure, management typically emphasizes maintaining quality of life and comfort for affected cats.

With appropriate treatment and management, many cats with heart murmurs can enjoy good quality of life for months to years after diagnosis. Your veterinarian will work with you to develop a personalized care plan tailored to your cat’s specific condition and needs.

When to Seek Emergency Care

While many cats with heart murmurs remain stable with proper management, certain signs warrant immediate veterinary attention:

• Labored breathing or open-mouth breathing
• Blue or pale gums
• Collapse or fainting
• Significant lethargy or weakness
• Paralysis of limbs (rare but can occur with certain heart conditions)

These symptoms may indicate decompensation of heart function or complications requiring urgent medical intervention.

Frequently Asked Questions

Q: Can cats with heart murmurs live normal lives?

A: Many cats with heart murmurs, especially those with functional or low-grade murmurs, can live completely normal lives without any treatment. Even cats with more serious underlying heart conditions can often enjoy good quality of life with appropriate medical management.

Q: Are certain cat breeds more prone to heart murmurs?

A: Yes, some breeds have genetic predispositions to heart conditions that cause murmurs. Maine Coons, Ragdolls, Persians, and Sphynx cats have higher rates of hypertrophic cardiomyopathy, while Siamese cats may be more prone to certain congenital heart defects.

Q: How often should cats with heart murmurs see the veterinarian?

A: This depends on the severity and cause of the murmur. Cats with benign murmurs might need checkups every 6-12 months, while those with progressive heart disease may require evaluations every 3-6 months. Your veterinarian will recommend an appropriate monitoring schedule.

Q: Can a heart murmur in cats go away on its own?

A: In some cases, yes. Functional murmurs related to stress, fever, or anemia may resolve when the underlying condition improves. Some congenital murmurs in kittens can disappear as they grow and their hearts develop. However, murmurs caused by structural heart disease typically don’t resolve without treatment.

Q: How expensive is treatment for a cat with a heart murmur?

A: Costs vary widely depending on the diagnosis and treatment plan. Initial diagnostics (echocardiogram, X-rays, blood tests) can be relatively expensive, while ongoing medication costs range from affordable to significant depending on the medications required. Your veterinarian can provide cost estimates specific to your cat’s condition.

Understanding heart murmurs and their implications for your cat’s health empowers you to make informed decisions about their care. By working closely with your veterinary team and remaining vigilant for changes in your cat’s condition, you can help ensure the best possible quality of life for your feline companion, regardless of their cardiac status.

Author

Shinta

 

Shinta is a biotechnologist turned writer. She holds a master's degree in Biotechnology from Karunya Institute of Technology and Sciences and a PG Diploma in cellular and molecular diagnostics from Manipal University. Shinta realised her love for content while working as an editor for a scientific journal.

Read full bio of Shinta