Heart Murmur in Cats: Signs, Causes, and When to See a Vet

A heart murmur in cats is an abnormal sound heard during a veterinary exam, often indicating an underlying cardiovascular issue. While sometimes benign, a murmur necessitates a thorough evaluation to understand its cause and potential impact on your cat’s health (heart and lung diseases).

As an owner who has navigated complex feline health concerns, I understand the worry a heart murmur can bring. This guide, drawing on expert veterinary knowledge, aims to clarify what a murmur means for your cat and how you can best support their well-being.

We will cover common causes, diagnostic steps, and crucial signs that require immediate veterinary attention, distinguishing them from situations where monitoring is appropriate. Remember, this information is for educational purposes and does not replace professional veterinary diagnosis or treatment.

Why Understanding a Heart Murmur in Cats Matters

Discovering your cat has a heart murmur can be unsettling, but understanding what it signifies is crucial for their long-term health. A heart murmur isn’t a disease itself, but rather a sign that something is affecting the normal flow of blood through the heart. This turbulence can stem from various issues, ranging from minor, non-progressive conditions to severe, life-threatening heart diseases. The Cornell Feline Health Center emphasizes that early detection and understanding of heart murmurs are key to managing potential underlying conditions like hypertrophic cardiomyopathy (HCM), the most common heart disease in cats.

For owners, recognizing the significance of a murmur means taking proactive steps. It prompts necessary diagnostic tests, such as echocardiograms, which provide a detailed look at the heart’s structure and function. This allows veterinarians to identify the specific cause-whether it’s a congenital defect present from birth, acquired valve disease, or a progressive condition like HCM. Without this evaluation, an innocent murmur could be mistaken for a serious one, or worse, a serious murmur could be overlooked, delaying critical treatment. This proactive approach, grounded in expert veterinary advice from sources like the Cornell Feline Health, can significantly impact your cat’s quality of life and longevity.

Heart Murmur in Cats: Wait and Watch vs. Call Your Vet Now

When a heart murmur is detected, your veterinarian will be the primary guide for determining the next steps. However, understanding the potential implications can help you monitor your cat at home. Some murmurs are benign and may not require immediate intervention, while others signal a serious condition that demands urgent attention. It’s essential to distinguish between these scenarios to ensure your cat receives appropriate care.

Wait and watch:

• Grade I or II murmurs: These are very soft murmurs, often only audible to a trained ear, and may not be associated with any underlying disease. If your vet identifies such a murmur without other clinical signs, they may recommend monitoring.
• No accompanying symptoms: If your cat remains active, eats well, breathes comfortably at rest, and shows no signs of lethargy or distress, a murmur might be considered ‘innocent’ or benign.
• Stable condition over time: If a murmur has been present for a long time without any progression in its grade or the development of other symptoms, your vet might opt for a ‘wait and watch’ approach.
• Mildly improve cardiac biomarker: A slightly increased level of a cardiac biomarker like proBNP, without other significant findings on an echocardiogram or clinical signs, might warrant closer monitoring rather than immediate aggressive treatment.
• Benign cause identified: If diagnostic tests clearly indicate a non-progressive or benign cause for the murmur, and your cat is asymptomatic, routine follow-ups may suffice.

Call your vet now:

• Sudden onset of difficulty breathing or rapid breathing: Respiratory rate exceeding 40 breaths per minute while resting, or visible effort to breathe (abdominal panting, open-mouth breathing).
• Lethargy or extreme weakness: Your cat is unusually tired, reluctant to move, or collapses.
• Pale or bluish gums/tongue: Gums that appear white, pale pink, or blue/purple indicate poor oxygenation. A capillary refill time longer than 2 seconds when you gently press the gum can also signal poor circulation.
• Loss of appetite or refusal to eat for more than 24 hours: A significant change in eating habits can be a sign of serious illness.
• Sudden hind limb paralysis or weakness: This can be a sign of a blood clot (thromboembolism), a dangerous complication of heart disease.
• Vomiting or diarrhea lasting more than 24 hours, especially if accompanied by other symptoms.
• Any significant, sudden change in behavior, such as hiding, aggression, or disorientation.
• Known severe heart disease with new or worsening symptoms, indicating potential congestive heart failure.

The Merck Vet Manual highlights that the clinical signs of congestive heart failure can be subtle initially but progress rapidly. Recognizing these red flags allows for prompt veterinary intervention, which can be life-saving.

Steps to Take After a Heart Murmur Diagnosis

1. Schedule a Veterinary Consultation: If you suspect your cat has a murmur or if it was detected during a routine exam, the first and most critical step is a thorough veterinary assessment. This involves a physical examination, listening carefully to the heart sounds, and discussing your cat’s history and any observed changes.
2. Undergo Diagnostic Testing: Your veterinarian will likely recommend further diagnostics to determine the cause and severity of the murmur. This often includes blood work to check for underlying conditions like hyperthyroidism or anemia, and potentially a cardiac biomarker test like proBNP. Chest X-rays can assess heart size and lung health. The definitive diagnostic tool is typically an echocardiogram (ultrasound of the heart), which provides detailed images of the heart’s structure and function. The JAVMA has published research on cardiac diagnostics in cats, noting the importance of these tools.
3. Understand the Diagnosis: Work with your vet to fully understand the findings. Is the murmur congenital or acquired? Is it related to a specific condition like HCM? What is the grade and location of the murmur? What is the prognosis? Knowing the specifics will guide your home care and monitoring.
4. Implement Recommended Medical Treatment: If an underlying condition is identified, your vet will prescribe a treatment plan. This might include medications to manage heart rate, blood pressure, fluid retention (diuretics), or to prevent blood clots. Adhering strictly to the prescribed medication schedule is vital.
5. Provide a Heart-Healthy Diet: Your veterinarian may recommend a specific diet tailored to support cardiovascular health. This could involve managing sodium intake, ensuring adequate taurine levels, or providing nutrients that support heart muscle function. Discuss dietary options with your vet.
6. Monitor Closely for Changes: Regularly observe your cat for any new or worsening symptoms. Pay attention to their breathing rate at rest, energy levels, appetite, and any signs of distress. Keep a log of these observations to share with your vet during follow-up appointments.
7. Schedule Follow-Up Appointments: Regular check-ups are essential to monitor the progression of any heart disease and the effectiveness of treatment. Your vet will determine the frequency of these visits, which could range from every few months to annually, depending on the condition’s stability.

Common Misconceptions About Heart Murmurs in Cats

Myth: All heart murmurs in cats are serious and indicate severe heart disease.

Reality: This is not true. While many heart murmurs are caused by underlying heart disease like hypertrophic cardiomyopathy (HCM), some murmurs are considered ‘innocent’ or ‘benign.’ These are often heard in young cats or can be caused by temporary factors like excitement or anemia. They do not signify structural heart disease and typically do not require treatment, though they should still be evaluated by a veterinarian to rule out other issues. The Texas A&M College of Veterinary Medicine notes that innocent murmurs can resolve on their own.

Myth: If my cat has a heart murmur, they will show obvious symptoms of illness.

Reality: Many cats with heart murmurs, especially in the early stages of heart disease, show no outward signs of illness. The murmur is often detected incidentally during a routine physical examination. Symptoms like difficulty breathing, lethargy, or exercise intolerance typically develop as the heart disease progresses and the heart’s ability to function adequately declines. The iCatCare organization highlights that owners might not notice symptoms until the disease is quite advanced.

Myth: A heart murmur detected in a kitten will resolve as they grow older.

Reality: While some murmurs in kittens can be related to temporary physiological changes or minor congenital issues that may resolve, others are indicative of serious congenital heart defects that will persist. Conditions like ventricular septal defects (VSD) or atrial septal defects (ASD) may be present from birth and require veterinary management. The Cornell Feline Health provides information on congenital heart disorders in cats, stressing the need for proper diagnosis.

Myth: If my cat has a heart murmur, there’s nothing that can be done to help them.

Reality: This is a misconception that can lead to unnecessary despair. While some severe heart conditions may have a guarded prognosis, many cats with heart murmurs can live comfortable lives for years with appropriate management. Treatment plans, often involving medication, dietary changes, and regular monitoring, are designed to manage symptoms, slow disease progression, and improve quality of life. The goal is often to prevent complications like congestive heart failure or blood clots.

What to Track for Your Cat with a Heart Murmur

For cat owners whose pets have a diagnosed heart murmur, diligent observation is key. Keeping a detailed record of your cat’s behavior and physical signs can provide invaluable information to your veterinarian, aiding in the management of their condition. Here’s a checklist of what to monitor:

• Respiratory Rate at Rest: Count the number of breaths your cat takes per minute while they are calm and resting. A normal rate is typically between 20-30 breaths per minute. An improve rate (above 40 bpm) or visible effort in breathing (chest or abdominal movements) is a significant concern.
• Activity Level and Endurance: Note any changes in your cat’s willingness to play, jump, or explore. Decreased activity, reluctance to move, or getting tired very quickly during normal activities can indicate worsening heart function.
• Appetite and Thirst: Monitor how much your cat is eating and drinking. A decreased appetite or increased thirst can be associated with various health issues, including heart disease complications.
• Weight Changes: Keep track of your cat’s weight. Unexplained weight loss can be a sign of underlying disease, while sudden weight gain might indicate fluid retention due to heart failure.
• Coughing or Gagging: While less common in cats than dogs, persistent coughing or gagging can sometimes be related to heart conditions causing fluid buildup in the lungs.
• Gum Color and Capillary Refill Time (CRT): Gently lift your cat’s lip to observe gum color. They should be pink. Pale, white, or bluish gums are emergency signs. To check CRT, press lightly on the gum; the color should return within 1-2 seconds. A longer CRT suggests poor circulation.
• Behavioral Changes: Observe for unusual behaviors such as hiding more than usual, increased vocalization, confusion, or sudden aggression, which could signal pain or distress related to their condition.
• Presence of Swelling: Check for any unusual swelling, particularly in the legs or abdomen, which could indicate fluid buildup.
• Stool and Urine Output: Significant changes in urination or defecation patterns can sometimes be linked to systemic issues affecting the heart.

Regularly documenting these observations will help your veterinarian assess your cat’s condition and adjust treatment as needed. The University of Illinois Veterinary Medicine offers insights into when to be concerned about heart murmurs.

Frequently Asked Questions About Heart Murmurs in Cats

Conclusion: Partnering with Your Vet for Your Cat’s Heart Health

A heart murmur in cats is a significant finding that warrants careful attention and a partnership with your veterinarian. While the sound itself isn’t a diagnosis, it serves as a crucial indicator for potential underlying cardiovascular issues. By understanding the possibilities, knowing what signs to monitor at home, and trusting your vet’s diagnostic expertise, you can provide the best possible care for your feline companion.

Remember, early detection, accurate diagnosis through tools like echocardiography, and consistent management are key to supporting your cat’s heart health and ensuring they live a long, comfortable life. Always consult your veterinarian for any health concerns regarding your cat.

Sources

• Cornell
• AVMA
• Merck Vet Manual
• ASPCA
• UC Davis Vet Med