Cats like dogs and humans can suffer from heart disease. It’s interesting to note that each of these species is prone to a different form of heart disease. Humans are most likely to have coronary artery disease which may cause heart attacks. Dogs most commonly have valvular disease in which one or more of the valves in the heart leaks and allows blood to flow in the wrong direction. The most commonly diagnosed heart disease in cats is cardiomyopathy or disease of the heart muscle rather than valvular or coronary disease. Although each species has its predominant form of heart problems any of these heart problems can occur in man, dogs, or cats.
Cardiomyopathy accounts for almost two thirds of heart disorders diagnosed in cats. It is a structural abnormality of the muscle forming the heart wall resulting in either a thickened or thin emaciated and scarred wall of the heart. In either case the muscle becomes incapable of pumping adequate blood to nourish itself or the rest of the body. The result is congestive heart failure. When congestive heart failure occurs, fluid accumulates both in and around the lungs resulting in increasing difficulty breathing eventually leading to death. In some instances, congestive heart failure may also cause release of blood clots which can lead to sudden death or paralysis of the rear legs.
Cardiomyopathy’s cause in cats is not fully understood. It may develop as the result of anemia, thyroid disease or high blood pressure. However, most commonly the cause is unknown or genetic as demonstrated by the increase incidence of cardiomyopathy in certain feline breeds. Studies have demonstrated that Maine Coons, Ragdolls, and Persians are at elevated risk for cardiomyopathy, but no cat is immune to its threat.
Unfortunately feline cardiomyopathy tends to be a hidden disease not recognized by the cat’s family until advanced disease is present. At this point, the patient may be having difficulty breathing or may be dragging paralyzed legs. Once these advanced signs develop, therapy becomes much more difficult.
Identifying heart disease in your cat starts with regular physical examinations by your veterinarian. As part of the annual or biannual check-up, your veterinarian will carefully listen to the patient’s heart and lungs. Many times we can detect heart problems before your cat develops congestive heart failure. Abnormal heart sounds which are sometimes heard include murmurs, arrhythmias, gallop sounds, and abnormal lung sounds. When these abnormal sounds are found, we may recommend further testing to determine the specific type of cardiomyopathy (there are 3 forms), and to evaluate the severity of heart disease. We will also determine whether congestive heart failure is present or seems to be imminent.
There several tests necessary to properly evaluate a feline patient with heart disease. Depending on the patient’s status, one or more combinations of these tests may be recommended. Exams often recommended may include blood samples, ECG, blood pressure measurement, X-rays, and echocardiography.
Blood samples taken to assess the presence of anemia and over active thyroid (hyperthyroidism). Many times if hyperthyroidism or anemia are identified and corrected, we can reverse developing heart disease. In addition, recently developed blood tests look at biomarkers produced by diseased heart muscle. Biomarkers may give one the earliest clues to developing heart disease and may help guide us in further testing or monitoring the progression of disease.
Blood pressure also is evaluated as elevated blood pressure (hypertension) can trigger feline heart disease. Lowering blood pressure to the normal range may arrest or reverse developing cardiomyopathy.
X-ray allowing us to visualize the size and shape of the heart plus to evaluate accumulating fluid in or around the lungs. Determination of fluid in the chest is critical to developing a proper therapeutic plan for the patient. This information will help us decide both when to start and what medications should be prescribed.
Finally, the most accurate instrument used to evaluate heart disease is ultrasound of the heart (echocardiography). Echocardiography allows us to look inside a beating heart. We can visualize wall thickness and motion, chamber size, valve motion and direction of flow of blood within the heart. These findings produce a very accurate evaluation of the stage of disease and can be critical in determining proper therapy. Echocardiography is considered the gold standard of diagnostic tools for feline cardiomyopathy.
Therapy for cardiomyopathy depends both on the type and severity of the disease. In early stages no treatment may be necessary, but as the disorder progresses medications may be started and adjusted as disease continues to advance. If congestive heart failure develops, medications are chosen to reduce fluids accumulating in the chest.
One difficult problem facing us is finding which if any drugs safely and effectively controls blood clot formation. To date no clot altering drugs have been found which reduce development of clots in cardiomyopathy.
Unfortunately there are cats in which the disease will progress and lead to life threatening illness or death despite therapy. However there are also many cats with cardiomyopathy that can live for years when stabilized.
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