Though hypertrophic cardiomyopathy (HCM) is much more commonly diagnosed in cats, dilated cardiomyopathy (DCM) is occasionally seen also.
Differences Between Feline Hypertrophic Cardiomyopathy and Dilated Cardiomyopathy
In cats with hypertrophic cardiomyopathy, the heart muscle of ventricles of the heart are thickened. This thickening causes the heart to have difficulty in pumping the blood through the heart and the rest of the body properly. The heart usually appears to be enlarged because of this thickening but the diameter of the chambers inside of the ventricles of the heart are usually normal in size or sometimes even smaller than normal.
Unlike hypertrophic cardiomyopathy, in cats with dilated cardiomyopathy, the chambers of the heart are dilated and larger than normal. The increased size of the chamber results in an increase in the volume of blood in the chamber as well. This increase in volume causes the muscle of the heart to work harder to move the blood, which in turn causes the muscle to thicken.
Causes of Dilated Cardiomyopathy in Cats
The most common cause of dilated cardiomyopathy in cats is a deficiency of taurine in the diet.
In the past, before the importance of taurine became widely known, many commercial cat foods contained inadequate amounts of taurine. However, most of the commercially available cat diets now contain taurine at the proper levels. As a result, dilated cardiomyopathy in cats is not as commonly seen as it was previously. However, it can still be seen in cats eating improperly balanced diets, such as some of the home-cooked diets.
Signs of Dilated Cardiomyopathy in Cats
Cats with dilated cardiomyopathy can suffer both right- and left-sided congestive heart failure. Commonly seen signs include:
- difficulty breathing
- lethargy
- inappetence
- fluid in the abdominal cavity (ascites)
- swelling in the legs
- weakness
- fainting spells (due to an irregular heart rate)
- cyanosis (lack of oxygen reaches the body causing a blue or purple color in the gums)
Aortic thromboembolism can also occur in dilated cardiomyopathy. This condition occurs when a blood clot that forms in the heart breaks loose and becomes stuck at the end of the aorta (the large vessel that carries blood from the heart to the rest of the body). The blood clot stops the blood flow through the aorta and cuts off the circulation to the hind legs. Cats suffering from an aortic thromboembolism will become paralyzed suddenly and become quite painful. Difficulty breathing and/or a rapid respiratory rate may be seen as well.
Sudden death can also occur in cats with dilated cardiomyopathy.
Learn More: Diagnosis and treatment of dilated cardiomyopathy