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Feline Cardiomyopathy
The most common cardiomyopathy (heart muscle
disease) in cats is hypertrophic cardiomyopathy. This form has many variations and is
defined by thickening of the primary heart muscle, the left ventricle. Depending on the
specific variation, the problem can be primarily in the blood flowing out of or into the
cat's heart. This differentiation using echocardiographic and other examination findings
helps determine which medications your cat requires. With appropriate medication and early
intervention, we can frequently achieve stabilization of the disease and sometimes
reversal of the problems.
A genetic predisposition to develop hypertrophic cardiomyopathy has been found in Maine Coon and American shorthair cats with a suspected genetic predisposition in ragdolls and Persians. The 1 to 4 year age group of cats has a tendency toward more aggressive disease. Male cats are also over represented. A common secondary change in cats with cardiomyopathy is enlargement of the left atrium. This finding is particularly worrisome in cats because they are susceptible to blood clot formation. If your cat has an enlarged left atrium, we may prescribe aspirin therapy (children's aspirin twice weekly is safe in cats) or other medication to try to delay or prevent blood clot formation. Unfortunately, the development of a blood clot is unpredictable and can occur on any medication. Blood clot formation can result in a cat being paralyzed in the rear legs, limping on a front leg, exhibiting episodes of abnormal behavior, or even sudden death. Older cats may have a thickened heart muscle due to an underlying systemic cause. In our middle aged and older cats high blood pressure, kidney disease, and hyperthyroidism are common problems that increase the workload of the heart muscle and cause secondary thickening. We always try to rule out a potential underlying cause before we make the diagnosis of hypertrophic cardiomyopathy. If your cat has another problem, the response to therapy for that primary problem usually improves and may resolve the secondary heart changes. The response to any therapy depends on the stage of disease with the best response seen when therapy is started earlier in the course of the problem. Restrictive cardiomyopathy is another type of heart muscle disease. This form can be a late stage of hypertrophic disease or may be a primary entity. Unfortunately, restrictive cardiomyopathy presents a much greater challenge in its treatment. These cats tend to have very large left atria and are usually at high risk for the development of a blood clot and heart failure. Both types of cardiomyopathy can cause congestive heart failure (fluid in the lungs). Sometimes, there will also be fluid around the lungs in cats with heart failure (pleural effusion) and that problem is best treated with physical removal of the fluid. If your cat has experienced an increased effort or rate of respiration, he or she may have experienced an episode of heart failure. Multiple medications are typically recommended to improve this situation and try to maintain your cat's normal lifestyle and appetite. If your cat has not been eating for several days, we may also recommend placement of a feeding tube to provide the calories and fluid your cat needs to recover. Unfortunately, feline patients hide signs of disease instinctively and many times present with advanced forms of cardiomyopathy because they have hidden their problems so well. As with all heart disease, early diagnosis is the key to achieving the best possible clinical response. |
