Hypertrophic Cardiomyopathy
Hypertrophic Cardiomyopathy (HCM) is the most common heart disease in cats, characterized by abnormal thickening of the left ventricular wall. This thickening reduces the heart's ability to relax and fill properly (diastolic dysfunction), potentially leading to heart failure, thromboembolism, or sudden death.
Symptoms & Signs
- Often asymptomatic in early stages
- Rapid or labored breathing
- Lethargy and reduced activity
- Loss of appetite
- Sudden hind limb paralysis (thromboembolism)
- Heart murmur on auscultation
- Gallop rhythm
- Sudden death
Causes & Risk Factors
HCM has a strong genetic component, with mutations in cardiac sarcomere protein genes (e.g., MYBPC3 in Maine Coons and Ragdolls). Secondary causes include hyperthyroidism, systemic hypertension, and aortic stenosis. The condition involves myocyte hypertrophy and myocardial fibrosis.
Diagnosis
Echocardiography is the gold standard, revealing left ventricular wall thickness >6mm in cats. Additional diagnostics include cardiac biomarkers (NT-proBNP, cardiac troponin I), ECG, thoracic radiography, and genetic testing for known mutations.
Treatment
Treatment aims to manage symptoms and prevent complications. Beta-blockers (atenolol) or calcium channel blockers (diltiazem) improve diastolic filling. Anticoagulants (clopidogrel) prevent thromboembolism. Diuretics manage congestion. ACE inhibitors may be added for heart failure.
Prevention
Genetic testing and selective breeding in known affected breeds. Regular cardiac screening (echocardiography) for at-risk breeds. Avoiding breeding of affected individuals or known carriers.
Prognosis
Highly variable. Some cats remain asymptomatic for years. Once heart failure or thromboembolism develops, median survival is 3-18 months. Sudden death can occur without prior symptoms.
Affected Breeds (32)
| Breed | Species | Size |
|---|---|---|
| American Shorthair | Cat | Medium |
| Bengal | Cat | Large |
| Birman | Cat | Medium |
| Bombay | Cat | Medium |
| British Longhair | Cat | Medium |
| British Shorthair | Cat | Large |
| Chartreux | Cat | Large |
| Cornish Rex | Cat | Small |
| Devon Rex | Cat | Small |
| Egyptian Mau | Cat | Medium |
| Exotic Shorthair | Cat | Medium |
| Himalayan | Cat | Medium |
| Japanese Bobtail | Cat | Medium |
| Maine Coon | Cat | Large |
| Norwegian Forest Cat | Cat | Large |
| Ocicat | Cat | Large |
| Oriental Shorthair | Cat | Medium |
| Persian | Cat | Medium |
| Peterbald | Cat | Medium |
| Pixie-Bob | Cat | Large |
| Ragamuffin | Cat | Large |
| Ragdoll | Cat | Large |
| Russian Blue | Cat | Medium |
| Savannah | Cat | Large |
| Scottish Fold | Cat | Medium |
| Selkirk Rex | Cat | Medium |
| Siberian | Cat | Large |
| Snowshoe | Cat | Medium |
| Sphynx | Cat | Medium |
| Tonkinese | Cat | Medium |
| Toyger | Cat | Medium |
| Turkish Angora | Cat | Medium |