Adopting a Cat With a Heart Murmur: Grades and Monitoring

Last updated: May 6, 2026

Why a Heart Murmur Should Not Stop You From Adopting

A heart murmur diagnosis on a shelter cat’s medical record can feel intimidating, but it does not have to be a dealbreaker. Many cats with heart murmurs live long, happy, and relatively normal lives — especially when the murmur is low-grade and properly monitored. If you are considering adopting a cat with a heart murmur, understanding what the diagnosis means and what to expect will help you make a confident, compassionate decision.

A heart murmur is simply an abnormal sound heard through a stethoscope during a physical exam. It indicates turbulent blood flow within the heart, which can range from completely harmless to a sign of underlying heart disease. The severity depends on the grade, the cat’s age, and whether structural heart changes are present.

Cats with heart murmurs are among the most overlooked animals in shelters. Many adopters pass them by out of fear, but with the right information, you may find that your perfect companion has a soft whoosh in their heartbeat and a whole lot of love to give.

Understanding Heart Murmur Grades in Cats

Veterinarians grade heart murmurs on a scale of I to VI based on how loud the abnormal sound is when heard through a stethoscope. The grade gives a rough indication of severity, though it does not always correlate directly with the seriousness of the underlying condition.

Grade I

Barely audible, even in a quiet room. These murmurs are often incidental findings and may not indicate any structural heart disease. Many cats with grade I murmurs require no treatment at all.

Grade II

Soft but readily heard with a stethoscope. Grade II murmurs are common in cats and, like grade I, may be benign — especially in kittens, where they sometimes resolve on their own as the heart matures.

Grade III

Moderately loud. A grade III murmur typically warrants further investigation with an echocardiogram (heart ultrasound) to determine whether structural changes are present.

Grade IV

Loud and accompanied by a palpable vibration (thrill) on the chest wall. Further diagnostic workup is strongly recommended.

Grades V and VI

Very loud, with a thrill palpable over a wide area. Grade VI murmurs can even be heard without a stethoscope. These typically indicate significant heart disease that requires ongoing veterinary management.

It is important to know that murmur grade alone does not predict a cat’s quality of life or lifespan. Some cats with grade III murmurs have mild, stable conditions that never progress, while occasionally a lower-grade murmur can accompany a more serious issue. An echocardiogram is the gold standard for understanding what is happening inside the heart.

Common Causes of Heart Murmurs in Cats

Heart murmurs can be caused by a variety of factors, some benign and others requiring management. Knowing the potential causes helps you ask the right questions when adopting.

Innocent or physiologic murmurs. These occur without any structural heart disease. Stress, fever, anemia, or even anxiety during a vet visit can create temporary turbulent blood flow that produces a murmur. Kittens are particularly prone to innocent murmurs that disappear by six months of age.

Hypertrophic cardiomyopathy (HCM). The most common heart disease in cats, HCM causes thickening of the heart muscle. It is particularly prevalent in breeds like Maine Coons, Ragdolls, and British Shorthairs, but it can affect any cat. HCM ranges from mild and manageable to severe.

Hyperthyroidism. An overactive thyroid gland increases heart rate and blood flow, which can produce a murmur. This is more common in older cats and is treatable with medication, diet, or surgery.

Congenital heart defects. Some cats are born with structural abnormalities like ventricular septal defects or valve malformations. These are less common but may be identified in young shelter cats.

When adopting, ask the shelter or rescue for any diagnostic records. If an echocardiogram has already been performed, review the findings with your veterinarian. If not, scheduling one shortly after adoption gives you a clear baseline.

What to Expect: Monitoring and Veterinary Care

Adopting a cat with a heart murmur means committing to a monitoring schedule. The good news is that for many cats, this is straightforward and not overly burdensome.

Baseline echocardiogram. If one has not been done, an echocardiogram within the first few weeks of adoption is the most important step. It reveals the structure and function of the heart and helps your vet determine whether the murmur is benign or connected to a condition like HCM.

Regular checkups. Cats with benign or low-grade murmurs may only need a vet visit every 6 to 12 months. Cats with confirmed heart disease typically need echocardiograms every 6 to 12 months depending on severity and progression.

At-home monitoring. Your vet may teach you to count your cat’s resting respiratory rate at home. A consistently elevated rate (over 30 breaths per minute at rest) can be an early warning sign of fluid buildup in the lungs. This simple check takes 15 seconds and can catch changes before they become emergencies.

Medication. Not all heart murmurs require medication. If your cat’s echocardiogram reveals HCM or another condition, your vet may prescribe medications such as atenolol to slow the heart rate, clopidogrel to prevent blood clots, or furosemide if fluid retention becomes an issue.

Estimated Costs of Caring for a Cat With a Heart Murmur

Financial preparedness is part of responsible adoption. Here is a realistic breakdown of potential costs, though prices vary by location and clinic.

• Initial echocardiogram: $300 to $600. This is the most significant upfront cost and provides the diagnostic foundation for your cat’s care plan.
• Follow-up echocardiograms: $250 to $500 each, typically once or twice a year for cats with confirmed heart disease.
• Routine vet visits: $50 to $150 per visit, similar to any healthy cat.
• Medications (if needed): $20 to $80 per month, depending on the drug and dosage.
• Emergency care (if complications arise): $500 to $2,000+. Pet insurance or a dedicated savings fund can ease this financial pressure.

Many cats with low-grade murmurs incur little to no extra cost beyond the initial echocardiogram. Pet insurance is worth investigating before or shortly after adoption, as some plans cover pre-existing conditions after a waiting period, while others may exclude them. Shop around and read policy details carefully.

Practical Tips for Life With a Heart-Murmur Cat

Daily life with a heart-murmur cat is, in most cases, remarkably similar to life with any other cat. A few thoughtful adjustments can optimize their comfort and health.

Keep stress low. Stress can temporarily worsen cardiac symptoms. Provide quiet retreats, predictable routines, and gentle handling. If your cat needs vet visits, ask about low-stress handling techniques or consider a feline-friendly practice.

Maintain a healthy weight. Obesity places extra strain on the cardiovascular system. Feed a high-quality diet in measured portions and engage your cat in gentle play to keep them at an ideal body condition.

Avoid sudden intense activity. While normal play is fine and encouraged, avoid overstimulating a cat with known heart disease into prolonged sprinting or extremely energetic play sessions. Let your cat set the pace.

Learn the emergency signs. Open-mouth breathing, sudden hind-leg paralysis (a sign of a blood clot called a saddle thrombus), rapid labored breathing, and collapse are all emergencies. Know the location of your nearest emergency veterinary hospital and have a plan in place.

Build a relationship with a cardiologist. If your area has a veterinary cardiologist, establishing care early gives you access to specialized expertise and faster response times if your cat’s condition changes.

Frequently Asked Questions

How long can a cat with a heart murmur live?

Many cats with low-grade murmurs and no underlying disease live a normal lifespan of 15 years or more. Cats with mild HCM can also live many years with proper monitoring. Cats with severe heart disease have a more variable prognosis, but many still enjoy several quality years with appropriate management.

Should I adopt a kitten with a heart murmur?

Yes, in many cases. Kittens commonly have innocent murmurs that resolve by four to six months of age. A follow-up exam at that age can confirm whether the murmur has disappeared. Even if it persists, early detection gives you a head start on monitoring and care.

Will my cat need surgery for a heart murmur?

Surgery is rarely needed for heart murmurs in cats. Most conditions that cause murmurs, like HCM, are managed with medication and monitoring rather than surgical intervention. Congenital defects may occasionally warrant surgical correction, but this is uncommon.

Can a heart murmur cat live with other pets?

Absolutely. Cats with heart murmurs can live happily in multi-pet households. Just ensure they have access to quiet spaces where they can retreat if they feel stressed or overstimulated by housemates.

Is pet insurance worth it for a cat with a heart murmur?

Pet insurance can be a wise investment, especially if you adopt before the murmur is formally diagnosed and documented in medical records. Some policies cover cardiac conditions, including diagnostics and medications. Compare plans carefully, as coverage varies widely between providers.

Ready to open your heart and home? Browse cats available for adoption on our adoption page or visit the cat adoption hub for guides on finding your perfect feline match. For general health tips, check out the cat care blog.