Hypertrophic cardiomyopathy is a form of heart disease that is most frequently diagnosed in cats. Some cases are caused by high blood pressure or hyperthyroidism, but many cats develop the disease because of an underlying genetic predisposition. When a cat has hypertrophic cardiomyopathy, its heart cannot fill with blood and pump effectively because the muscular walls of one of the heart's chambers are greatly thickened.
Some cats with hypertrophic cardiomyopathy do not have any observable symptoms, and the disease may be picked up by a veterinarian during a routine physical exam when a heart murmur, rapid heart rate or abnormal heart rhythm is heard. Other animals may have difficulty breathing, lose use of their hind limbs and be in extreme pain when an abnormal blood clot disrupts their circulation, or collapse. Chest x-rays and an ultrasound of the heart are the best methods of definitively diagnosing hypertrophic cardiomyopathy. Blood work, blood pressure measurements, and other laboratory tests are used to look for any underlying causes.
If an underlying disorder can be found and treated, the heart disease will often resolve on its own over the course of several months. In other cases, medications that improve heart function, decrease abnormal accumulations of fluid within the body, and lessen the formation of blood clots can improve a cat's quality of life and extend its life expectancy. A cat's long-term prognosis depends on the severity of its disease. Most animals that develop congestive heart failure or abnormal blood clots as a result of hypertrophic cardiomyopathy die or are euthanized because of this disease.
Written by: Jennifer Coates, DVM
Last reviewed: October 2, 2008