Understanding Heart Murmurs in Cats
If your veterinarian mentions hearing a heart murmur in your cat, it's natural to feel concerned. But what exactly does this mean? Let's break down what a heart murmur is, why it occurs, and what it could mean for your feline friend.
What Is a Heart Murmur?
A heart murmur in cats is an abnormal sound heard when listening to the heart with a stethoscope. Instead of the usual steady "lub-dub" rhythm, the vet detects an extra "whooshing" noise. This sound comes from turbulent blood flow within the heart or nearby vessels.
Murmurs are classified by:
- Grade (loudness): Ranging from 1 (barely audible) to 6 (very loud and sometimes palpable).
- Configuration (timing): When during the heartbeat cycle the murmur occurs.
- Location: Where on the chest it's loudest.
The grade doesn't always match up with how serious the underlying issue is—a quiet murmur can signal severe disease, while a loud one might be harmless.
Types of Heart Murmurs
- Innocent or physiologic murmurs: Often found in healthy kittens or stressed adults. These are usually soft and not linked to disease; they often disappear as the cat matures or calms down.
- Pathologic murmurs: Caused by structural problems in the heart (like valve defects) or diseases elsewhere in the body (such as anemia or hyperthyroidism).
Common Causes of Heart Murmurs in Cats
- Congenital defects: ventricular septal defect (VSD), atrial septal defect (ASD), patent ductus arteriosus (PDA)
- Cardiomyopathies: especially hypertrophic cardiomyopathy (HCM), which is most common in cats
- Heart valve issues: insufficiencies or narrowing (stenosis)
- High blood pressure
- Anemia
- Hyperthyroidism
- Heartworm disease
- Endocarditis (infection of the heart valves)
Certain breeds—Maine Coons, Ragdolls, British and American Shorthairs, Siamese—are genetically predisposed to some heart conditions that can cause murmurs.
Symptoms of Underlying Heart Disease
Your cat may show no symptoms at all until heart disease becomes advanced. Still, keep an eye out for these signs:
- Lethargy or weakness
- Lack of interest in play or exercise intolerance
- Panting, labored or rapid breathing
- Poor appetite and weight loss
- Sneaking away to hide more than usual
- Pale or bluish gums
- Coughing, fainting, or collapse
- Buildup of fluid—sometimes seen as swelling or trouble breathing due to fluid in lungs
Kittens with severe disease may not grow well. In rare cases, sudden pain and paralysis in the hind legs can occur if a blood clot forms.
How Are Heart Murmurs Detected?
The majority of murmurs are found incidentally during routine vet visits. If your vet hears one, they'll recommend tests to figure out if it's benign or linked to disease. Diagnostic tools include:
- Echocardiogram (heart ultrasound): The gold standard for evaluating heart structure and function.
- X-rays: To check heart size and look for fluid buildup.
- Bood tests: To rule out anemia, hyperthyroidism, and other systemic diseases.
- Electrocardiogram (ECG): To assess for abnormal rhythms.
- Bood pressure measurement.
Treatment Options for Heart Murmurs in Cats
- No treatment needed for innocent/physiologic murmurs—just monitoring over time.
- If there's underlying disease:
- Certain medications for heart failure (like diuretics and cardiac drugs)
- Treatments for high blood pressure or thyroid issues if present
- Surgery/interventional procedures for specific congenital defects (rarely performed)
- Nutritional support and stress reduction at home
- Lifelong monitoring with regular check-ups and repeat imaging/bloodwork
Murmurs in young kittens sometimes resolve as they grow. For adult cats with disease-related murmurs, ongoing management is often necessary. Prognosis varies widely—from excellent with innocent murmurs to guarded if there's severe disease involved.
The Importance of Monitoring and Early Detection
Your best defense is regular veterinary care. Keep watch for changes in breathing, appetite, energy level—or any new symptoms—and see your vet right away if you notice anything unusual. Early detection can make a big difference by allowing timely intervention that improves both quality and length of life for affected cats. Still, many healthy cats with murmurs never develop clinical problems and live normal lives.
If your cat has been diagnosed with a murmur, don't panic—but do stay proactive about their health!
