Feline Heart Disease (HCM): Symptoms & Screening
Hypertrophic cardiomyopathy (HCM) is the most common heart disease in cats. Many cats show no symptoms until it's advanced.
HCM Progression & Detection
Screening Method
| Screening Method | What It Detects | Cost | Recommended For |
|---|---|---|---|
| Auscultation (Stethoscope) | Heart murmur, gallop rhythm, arrhythmia | $0 (part of exam) | All cats — every annual exam |
| NT-proBNP Blood Test | Heart muscle stretch biomarker | $50-$100 | At-risk breeds, senior cats, pre-anesthesia |
| Chest X-Ray | Heart enlargement, fluid in lungs | $150-$300 | Cats with symptoms or abnormal exam |
| Echocardiogram (Ultrasound) | Definitive diagnosis — measures wall thickness | $400-$800 | Gold standard; breeding cats, confirmed murmurs |
| Genetic Test (Maine Coon/Ragdoll) | MYBPC3 gene mutation | $40-$60 | Breeding cats of predisposed breeds |
HCM Warning Signs
| Labored or rapid breathing at rest (normal: 20-30 breaths/min) | |
| Open-mouth breathing or panting (EMERGENCY in cats) | |
| Hind leg weakness or paralysis (saddle thrombus — EMERGENCY) | |
| Lethargy, hiding, decreased appetite | |
| Heart murmur detected on exam (not all murmurs = HCM) | |
| Assume no murmur = no heart disease (some HCM cats have no murmur) | |
| Wait for symptoms before screening at-risk breeds | |
| Skip pre-anesthesia cardiac screening in senior cats |
Count your cat's resting breathing rate at home. Normal is 20-30 breaths per minute while sleeping. Consistently over 30-40 at rest = vet visit. This simple home monitoring can catch heart failure early.
Hind leg paralysis or sudden severe pain with cold hind paws is a SADDLE THROMBUS — a blood clot blocking blood flow to the legs. This is a life-threatening emergency. Go to the ER immediately. Time is critical.
Hypertrophic cardiomyopathy (HCM) is a thickening of the heart's left ventricle wall and is the most commonly diagnosed heart disease in cats, affecting an estimated up to 15% of the feline population. It has been diagnosed in cats as young as 4 months and as old as 16 years. Many cats show no symptoms at all in earlier stages, which is why diagnosis usually comes from a vet detecting a heart murmur or abnormal rhythm during a routine exam, confirmed with an echocardiogram, rather than from obvious signs at home.
One in seven cats may be living with this and showing nothing
Hypertrophic cardiomyopathy is the most common heart disease in cats, and it can hide behind a completely normal-looking cat for years.
petstore.comReading breathing and energy changes in a cat
HCM is often silent until it isn't
Many cats show no outward signs at all in earlier stages. Diagnosis usually comes from a vet hearing a heart murmur or irregular rhythm on a routine exam, not from an owner noticing symptoms first.
Breeds with documented higher risk
The most common cat heart disease often makes no noise at all
Hypertrophic cardiomyopathy is exactly what it sounds like: the muscle wall of the heart's left ventricle thickens over time. That thickening leaves less room for the chamber to fill with blood between beats, and the strain can cause the upper chamber above it, the left atrium, to enlarge. Left unmanaged, this can eventually progress toward congestive heart failure. What makes HCM particularly sneaky is how often it shows no outward symptoms at all while it is developing - a cat can look completely normal on the outside while this is happening internally.
The numbers involved are genuinely striking: HCM is the most commonly diagnosed cardiac disease in cats, and estimates put it affecting up to 15% of the general feline population. It has been documented in cats as young as 4 months old and as old as 16 years, which means age alone is not a reliable way to rule it out.
Genetics loads the dice for specific breeds
Certain breeds show up disproportionately often in HCM diagnoses, and mutations in several cardiac genes have been identified in some affected cats, pointing toward a real genetic component rather than pure chance. Breeds with documented higher prevalence include Maine Coon, Ragdoll, British Shorthair, American Shorthair, Sphynx, Bengal, Chartreux, Norwegian Forest, Siberian, and Persian cats. Owning one of these breeds does not mean a cat will develop HCM, but it does mean earlier and more regular heart screening is a reasonable, proactive step rather than an overreaction.
Screening itself is straightforward in concept even if it requires specialized equipment: an echocardiogram, an ultrasound of the heart, is how HCM is actually diagnosed, since it can directly show the thickened ventricle wall and reduced chamber volume that define the disease. A vet often first suspects something is off after hearing a heart murmur or irregular rhythm during a completely routine physical exam, which is exactly why regular wellness visits matter even for cats that seem perfectly healthy.
Not every case moves at the same speed
The prognosis for HCM varies widely from cat to cat. Cats without obvious clinical signs often live for years with only mildly reduced heart function, while others progress toward heart failure more quickly. This range is part of why "wait and see if symptoms appear" is not the recommended approach for predisposed breeds - by the time obvious symptoms like labored breathing show up, the disease may already be at a more advanced stage than a cat that was screened earlier.
The prevalence figure (up to 15% of the feline population), the description of HCM as the most commonly diagnosed cardiac disease in cats, the age range of diagnosed cats (4 months to 16 years), the list of predisposed breeds, the echocardiogram-based diagnosis method, and the variable prognosis described above all come from the Cornell Feline Health Center's dedicated hypertrophic cardiomyopathy resource for cat owners.
What is not backed by an approved source here: this article does not name a specific cost range for echocardiogram screening or a specific recommended screening interval by breed or age, because the Cornell material reviewed does not itemize those figures, and no other approved source in this article's list provided them either. Ask your vet directly about screening frequency and cost for your specific cat.