CATS · Condition guide
Feline hypertrophic cardiomyopathy: real veterinary cases
Hypertrophic cardiomyopathy (HCM) is the most common heart disease in cats, affecting roughly 15% of the general cat population and substantially more in certain breeds — Maine Coons, Ragdolls, British Shorthairs, Sphynx, and Persians are over-represented. The heart muscle thickens (especially the left ventricle), the chamber shrinks, and the heart can't relax properly between beats. Many cats live for years with mild HCM and never show symptoms; others progress to congestive heart failure or, terrifyingly, throw a clot into the aorta (aortic thromboembolism — a "saddle thrombus") that causes sudden, severe hind-limb paralysis.
A heart murmur picked up on a routine exam is the most common first clue — though about a third of cats with HCM have no audible murmur, and many cats with innocent murmurs don't have HCM. Confirming the diagnosis requires echocardiography (cardiac ultrasound). NT-proBNP is a useful screening blood test when echo isn't immediately available. Treatment depends on stage: subclinical disease often needs only monitoring, while symptomatic cats benefit from diuretics, beta-blockers, and anti-platelet drugs like clopidogrel to reduce clot risk.
What vets typically check for
- Thorough auscultation — listen for a murmur, gallop sound, or arrhythmia.
- NT-proBNP blood test as a screening tool (good negative predictive value).
- Echocardiography — the only way to definitively diagnose HCM and grade severity.
- Thoracic radiographs if congestive heart failure is suspected (tachypnoea, dyspnoea).
- Clopidogrel for cats at high risk of aortic thromboembolism; diuretics ± pimobendan when in heart failure.
Not a replacement for veterinary care. Use this to walk into the conversation prepared, not to self-diagnose.
Real cases from the veterinary literature
Peer-reviewed reports our semantic search surfaces for Hypertrophic cardiomyopathy (HCM) in cats. Click into any case for the full abstract — or run a personalised search with your pet's exact details.
- Surgical stabilization of craniocervical junction abnormalities in two cats.
The Journal of veterinary medical science · 2026 · Japan
Two cats were brought in because they were having trouble moving their legs and showed signs of coordination issues. After imaging tests, they were diagnosed with craniocervical junction abnormalities, which can affect the spinal cord. Both cats underwent surgery to stabilize the affected area using a custom titanium plate. While the surgery helped improve their ability to walk
- Case Report: Systemic reactive angioendotheliomatosis in a young cat with a history of esophageal strictures and balloon dilations
Frontiers in Veterinary Science · 2026 · CH
A 3.3-year-old male domestic shorthair cat was brought to the emergency vet with neurological issues, including seizures. He had a history of esophageal strictures that required balloon dilation, which may have contributed to his condition. Tests showed he had severe anemia and low platelet counts, and his symptoms worsened quickly, leading to cardiac arrest. Sadly, a necropsy
- Case Report: Feline adrenal pheochromocytoma with a synaptophysin-positive, chromogranin A-negative immunophenotype.
Frontiers in veterinary science · 2026 · South Korea
An 8-year-old neutered male domestic shorthair cat was brought in with severe watery diarrhea, lethargy, and not eating. After tests, the vet found chronic kidney disease and a large cystic mass on the right adrenal gland. The cat underwent surgery to remove the adrenal mass, which was diagnosed as a pheochromocytoma, a rare type of tumor. Thankfully, the cat recovered well aft
- Reproductive status and abnormal clinical signs after surgery are positively associated with hemoabdomen and autotransfusion in cats after ovariohysterectomy.
Journal of the American Veterinary Medical Association · 2026 · United States
A cat undergoing a spay surgery experienced significant bleeding during the procedure, which is known as hemoabdomen. Out of over 9,500 cats spayed, about 10% had some bleeding, and a small number needed a blood transfusion afterward. Cats that were in heat or pregnant were more likely to have bleeding issues. Signs that could indicate a problem after surgery include pale gums,
- Hypertrophic cardiomyopathy in cats: clinical prevalence, risk factors, and outcomes of arterial thromboembolism in a referral population in Tehran, Iran (2020-2024).
BMC veterinary research · 2026
A group of 7,013 cats in Tehran were evaluated for heart problems, and 638 were diagnosed with hypertrophic cardiomyopathy (HCM), a serious heart condition. Persian cats were the most affected breed, with over half showing signs of HCM. Factors like being an adult and having a high body weight increased the risk of developing this condition. Some cats with HCM also experienced
- Transvalvular pulmonary stent angioplasty for palliation of severe pulmonic stenosis in two cats.
Journal of veterinary cardiology : the official journal of the European Society of Veterinary Cardiology · 2026 · United States
Two cats with severe breathing problems due to a narrowed pulmonary valve (pulmonic stenosis) underwent a special procedure called transvalvular pulmonary stent angioplasty to help improve their condition. One cat had some immediate issues after surgery, including fluid in the lungs, but the other cat recovered without complications. Both cats showed good results in the weeks f
Frequently asked questions
- How worried should I be about a heart murmur?
- Many cat heart murmurs are 'physiological' or innocent — they don't reflect serious disease. But because HCM is so common, any murmur warrants follow-up. NT-proBNP is a good screening blood test, and echocardiography is definitive. Ask for an echo if the murmur is loud (grade 3+), if the cat is a breed predisposed to HCM, or if there are any clinical signs.
- What is a saddle thrombus?
- Aortic thromboembolism (ATE) is a clot — usually formed in the enlarged left atrium of an HCM cat — that lodges where the aorta splits at the back of the abdomen. The cat suddenly cannot use one or both hind legs, the legs are cold and painful, and the prognosis is guarded. Some cats survive with intensive care, but recurrence is common. Clopidogrel reduces (does not eliminate) the risk in high-risk cats.
- Can HCM be cured?
- No — but many cats live for years with subclinical HCM. Once heart failure or thromboembolism occurs, prognosis is more guarded. Early identification through screening (especially in predisposed breeds) gives the best chance of catching disease before complications occur.