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Cardiomyopathy
Cardiomyopathy is an alteration in the function of the heart muscle. It can occur for several reasons in cats and it can take several forms. When the muscle is sufficiently affected that it can not function properly, heart failure occurs.
Dilated cardiomyopathy due to taurine deficiency was common until recent years. The discovery of the relationship between taurine (an essential amino acid) deficiency and the development of dilated cardiomyopathy has nearly eliminated this condition.
Hypertrophic cardiomyopathy is now the more common form of this condition in cats. It can occur for several reasons, including hyperthyroidism, toxins, infections and genetic influences. In this disorder, the heart muscle loses elasticity and becomes thicker, making it hard for the heart to function properly. There are many apparent variations in the course of this disease in cats. At the present time, a clear understanding of the mechanism of the disease is not understood in most cases.
The symptoms of this problem are similar, despite variations in why they occur. Affected cats may exhibit difficulty breathing, rapid respiratory rate, weight loss or poor condition, loss of appetite, tire easily with exercise or show signs of weakness or paralysis of the rear legs. Despite the chronic nature of the disease itself, cats often appear to develop symptoms quite suddenly, especially difficulty breathing and rear leg weakness.
Physical examination is often sufficient to produce a presumptive diagnosis of cardiomyopathy. This disease is best confirmed with ultrasonagraphy but X-rays and electrocardiograms (ECG) can be helpful. Many affected cats have heart murmurs that are audible on exam. These are not diagnostic for cardiomyopathy since they can occur with other heart disease.
Cats with sudden real leg weakness are a clinical emergency. This occurs as the result of blood clots from the damaged heart blocking circulation to to the rear legs. The resulting damage to muscle can lead to the release of sufficient levels of potassium to cause death. Immediate treatment may be necessary. Provision of oxygen to enable the damage circulatory system to do its job of delivering sufficient oxygen to the body may be necessary.
Long term management of this problem through the use of medications is possible. At the present time, there is some controversy about all methods of treating this disease but some medications do seem to be beneficial in many cases. Aspirin is used to reduce the possibility of blood clots. Due to the strong possibility of poisoning from aspirin in cats it is extremely important that this be administered under a veterinarian's supervision and at the prescribed dosages. It has not been as effective as originally hoped. Diuretics are helpful in many cats, especially when heart failure develops. A group of medications know as ACE inhibitors (captopril, enalapril) are often beneficial in the long term management of heart failure in cats. Other medications to control heart rhythm or to to try to increase the muscle strength may be indicated. Until it is established that taurine deficiency is not the problem, it is worthwhile to supplement this amino acid in all cats with signs of cardiomyopathy.
At the present time, the long term prognosis for these conditions is
poor unless they are caused by either taurine deficiency or hyperthyroidism,
which are treatable conditions. Work is continuing on more effective ways
to diagnosis this problem and to treat it.
Please see http://www.vetinfo4cats.com/ccardio.html for more information on cardiomyopathy.
Last edited 01/13/08
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