Hypertrophic Cardiomyopathy (HCM) in Cats
Hypertrophic Cardiomyopathy (HCM) is a condition in which the muscular walls of a cat’s heart thicken, decreasing the efficiency of the pumping. Inefficient blood pumping can lead to a backup of blood to the other chambers of the heart and to the lungs, which may contribute to the development of congestive heart failure or the formation of blood clots in the heart.
The cause of HCM is unknown, but there appears to be a genetic component, with the following breeds more prone to develop the condition:
- American shorthair
- British shorthair
- Maine coon
- Scottish fold
- Turkish van
The condition is seen more often in male cats than females. Hyperthyroidism, high blood pressure, and aortic stenosis can mimic hypertrophic cardiomyopathy.
Many cats with HCM do not appear to be sick. Others may show the following signs:
- Labored or rapid breathing
- Open-mouth breathing
- Hindlimb paralysis from an aortic blood clot
HCM is diagnosed by echocardiography, a technology that uses sound waves to non-invasively create an image of the heart. In cats with HCM, these images reveal the thickened heart walls and decreased left ventricle volume. Since heart wall thickening is also caused by other conditions, including high blood pressure and hyperthyroidism, these diseases must be ruled out before diagnosing HCM. Your veterinarian may also recommend other tests, including chest radiographs and electrocardiography.
Treatment goals include controlling signs of heart failure, improving cardiac function, and reducing the formation of blood clots. Treatment must be tailored to the individual cat and might include diuretics (to reduce fluid buildup), calcium-channel blockers, beta-blockers, ACE inhibitors or anticoagulant drugs to help manage the condition.
No therapy has been shown to prevent the disease.