Hypertrophic Cardiomyopathy (HCM) is the most common heart disease in cats. In this disease, the heart muscle wall (primarily the left ventricle) becomes thickened and does not relax properly. Eighty percent of cats with HCM will have a heart murmur that is heard on routine physical examination. Maine Coon, American Shorthair, and Persian cats are breeds that are hereditarily predisposed to developing HCM, but HCM has been most commonly reported in the common Domestic Shorthair cat.
HCM is definitively diagnosed by performing an echocardiogram (an ultrasound of the heart) to evaluate the heart size, contractility, and thickness of the heart muscle. Although there is no definitive way to reverse this heart disease, medications are often prescribed to relax the heart muscle, slow the heart rate, or decrease fluid retention (diuretics). Cats with HCM are at risk for blood clot formation, abnormal rhythms of the heart (arrhythmias), and congestive heart failure.
The two most common heart diseases in dogs are disease of the mitral valve and dilated cardiomyopathy. Degeneration of the mitral valve is common in Dachshunds, Terriers, Poodles, and other small breed dogs. In this disease, the mitral valve does not close properly and blood leaks backward through the mitral valve. These patients will have a heart murmur heard during a routine physical examination.
Dilated Cardiomyopathy (DCM) is a disease of the heart muscle where the heart wall becomes thin and loses its ability to contract properly. This is most commonly seen in Doberman Pinschers, Boxers, Great Danes, and Dalmations. Because a heart murmur is often not heard until very late in this disease, we recommend routine screening of patients who are susceptible to this heart disease, especially Boxers and Doberman Pinschers.
Both of these diseases in dogs are diagnosed definitively by performing an echocardiogram (an ultrasound of the heart). Based on the stage of the disease, medications are often recommended to specifically treat either of these heart conditions. Dogs with DCM will commonly have arrhythmias (abnormal rhythms of the heart). In order to determine the extent of the arrhythmia, a Holter monitor (a 24-hour ECG monitor) may also be recommended in dogs that are susceptible to DCM.