The heart is a muscle that is responsible for circulating blood through the body. The heart consists of four chambers: the left and right ventricle and the left and right atrium. The heart pumps blood to the lungs, where the blood is oxygenated; the blood then returns to the heart to be pumped to the organs and extremities. Heart disease in cats is characterized by a change in the structure of the heart that affects its ability to pump blood. Heart disease in cats can be classified into three distinct forms: hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM) and restrictive cardiomyopathy (RCM).
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Hypertrophic Cardiomyopathy
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HCM is the most common form of feline heart disease. It is characterized by an enlargement of the heart muscle on the left wall of the heart. This enlargement leads to the inability of the left ventricle to adequately fill with blood, which, in turn, leads to a decrease in the amount of blood being circulated through the body. This inability to pump the blood may result in fluid buildup, called edema, in a cat's abdomen and lungs, which will make it hard for the cat to breathe.
Blood clots are also a potential problem for cats with HCM. Since the blood is not completely pumped from the heart, blood clots may form and become lodged in the aorta, which carries blood to the rear legs. This can be extremely painful and may lead to paralysis.
Dilated Cardiomyopathy
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DCM is characterized by the thinning of the walls of the heart and enlargement of the chambers. This thinning causes the muscle to become flabby, and the heart is unable to pump blood adequately. DCM in not seen very often in cats today. Due to advances in veterinary research, veterinarians determined that a deficiency of taurine, an amino acid, was the leading cause of DCM. Pet food companies now produce food that contains taurine, which has drastically reduced the occurrence of this disease.
Restrictive Cardiomyopathy
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RCM is characterized as a stiffening of the heart muscle. This is caused by scarring of the heart or inflammation. Due to this stiffening, the heart is unable to pump blood adequately to the body. RCM is usually hereditary and may be more common in purebred cats such as Persians, Siamese and Burmese.
Symptoms of Heart Disease
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Cats are very good at hiding pain and sickness, and you may not notice any signs until your cat becomes extremely ill. Signs to watch for include labored breathing, open mouth breathing, lethargy, decreased appetite, weight loss and coughing. These symptoms will get progressively worse as the condition progresses. Cats with heart disease may eventually go into complete heart failure. Their chest and abdomen may become filled with fluid, making it impossible for them to breathe.
Diagnosis and Treatment
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Many times, your veterinarian will pick up abnormal heart rhythms during routine examinations. He will perform tests to determine the underlying cause and form of the disease. These test may include electrocardiograms, X-rays and blood tests.
Treatment for heart disease begins by treating the underlying condition. If no underlying condition is found, treatment will consist of medications such as angiotesin-converting enzyme (ACE) inhibitors, which increase cardiac function, and diuretics to help remove excess fluids. Since cats with heart disease are prone to blood clots, a small dose of aspirin may be given to help thin the blood.
Prognosis
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Cats with heart disease may live for several years or may deteriorate very rapidly. Since the disease is usually well advanced before your cat begins showing signs, treatment options are limited, and the long-term prognosis is not very good.
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