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Care Guide

About Care Guides[x] These care guides are written to help your clients understand common conditions, tests, and procedures, as well as to provide basic information about pet care. They are based on the most up-to-date, documented information, recommendations, and guidelines available in the United States at the time of writing. Pharmaceutical product licensing, availability, and usage recommendations are based on US product information. Use the Download Handout button to generate a PDF for printing or e-mailing to your clients.

Feline Dilated Cardiomyopathy

    • Feline dilated cardiomyopathy (DCM) is a relatively rare condition in cats.
    • With DCM, the heart muscle becomes thin, stretched, and unable to contract properly.
    • Some cats respond to treatment, but for most others, the long-term outcome is poor.

    What Is Feline Dilated Cardiomyopathy?

    Dilated cardiomyopathy (DCM) is a disease in which the heart muscle becomes thin, stretched, and unable to contract effectively. DCM is relatively uncommon in cats, accounting for approximately 10% of all cardiomyopathies in cats. There are a few different causes of the condition:

    • Taurine deficiency-induced DCM: Cats are unable to make adequate amounts of the amino acid taurine, so they must receive a diet that contains enough taurine to provide what they can’t make. Because commercial pet food manufacturers tend to supplement cat food with taurine, a cat that receives a nutritionally complete and balanced diet formulated for cats is not at risk for this type of DCM. However, cats that live on table food or eat a diet that is not nutritionally complete may be at risk.
    • Idiopathic feline DCM: The exact cause of this type of DCM is unknown. A genetic component is suspected, but diagnosis generally involves ruling out other causes of feline DCM.
    • Other causes: Certain drugs and some congenital heart defects can damage the heart muscle and lead to feline DCM.

    The result of DCM is that the heart muscle becomes weakened and unable to contract normally; this reduces the amount of blood the heart sends out when it contracts. Eventually, the body’s organs (including the kidneys) begin to suffer damage from inadequate blood and oxygen supply; excess fluid can accumulate in the lungs; and the altered blood flow through the heart can lead to the formation of blood clots that can lodge in other areas of the body, including the legs and brain.

    What Are the Signs of Feline Dilated Cardiomyopathy?

    Heart failure is defined as a condition in which fluid builds up in or around the lungs as a result of impaired heart functioning. DCM tends to be a very “quiet” disease in cats until enough damage has been done to the heart to cause clinical signs relating to heart failure. In fact, it is rare for the disease to be detected before the cat is in heart failure. When this occurs, the following signs can occur:

    • Shallow, labored, or rapid breathing
    • Coughing or vomiting
    • Appetite loss
    • Tiredness or depression
    • Fainting or collapsing episodes
    • Severe weakness or pain in the legs caused by clots that form in the heart and move toward the legs

    How Is the Disease Diagnosed?

    DCM must be distinguished from other causes of heart failure, such as hyperthyroidism, high blood pressure, and heart defects. The diagnosis of DCM is based on medical history (including a nutritional history to check for evidence of taurine deficiency), physical exam findings, and specific tests that look closer at heart functioning and the health of the heart and lungs. During the physical exam, a stethoscope is used to listen to the heart and lungs to detect a heart murmur, abnormal heart rate or rhythm, or chest fluid. Murmurs are “extra” sounds (usually in between the heartbeats) heard when blood is flowing abnormally through the heart. If there is fluid in the chest or lungs, the lungs can sound abnormally loud or quiet. Feeling the legs and feet for warmth and pulses helps detect evidence of clots that may have lodged in the arteries carrying blood to the limbs. When DCM is suspected after a physical exam, some or all of these tests may be recommended to confirm the diagnosis:

    • Blood tests: to look for thyroid, kidney, or other diseases that can affect the heart
    • Blood pressure check: to check for high or low blood pressure
    • Radiographs (x-rays): to look for fluid in the chest or lungs and evaluate the size and position of the heart
    • Echocardiogram (heart ultrasound): to measure the thickness of the heart walls, look at overall heart chamber size and contractility, evaluate the motion of heart valves, and see blood clots
    • Electrocardiogram (ECG): to evaluate heart rate and rhythm

    How Is Feline Dilated Cardiomyopathy Treated?

    Many cats with DCM are experiencing an acute crisis when the veterinarian initially sees them for the disease. If a cat is having severe breathing problems or is otherwise unstable, diagnostic tests may need to be postponed or limited until the patient can withstand them. Too much stress can be fatal in a cat suffering from heart failure. Medications may be given to calm the cat or take some of the load off of the heart, oxygen may be administered to ease breathing, and fluid may be removed from the chest to allow the lungs to fill with air more effectively. Hospitalization may be necessary to get the heart failure under control.

    Once a cat has been stabilized and a diagnosis of DCM confirmed, treatment will likely include medication to decrease the amount of work the heart has to perform, improve the heart muscle’s ability to contract, control heart arrhythmias, and help remove fluid from the lungs and chest cavity. Anti-clotting medications may also be prescribed to help during a crisis and prevent new clots.

    If a cat develops DCM as a result of inadequate taurine in the diet, a critical component of treatment is to supplement taurine and wean the cat onto a diet that contains adequate levels of the amino acid and other nutrients.

    What Is the Outcome for Cats With This Disease?

    Because most cats with DCM are already in heart failure when the disease is detected, the outcome tends to be poor. One notable exception may pertain to cats that develop DCM as a result of taurine deficiency. Long-term outcome may be somewhat favorable for these patients—as long as they respond quickly to treatment and receive adequate taurine on a regular basis. In some of these cases, full recovery has been reported and heart medication can be discontinued. However, if the DCM was not secondary to taurine deficiency, most cats eventually die from complications associated with heart failure.

    Your veterinarian will likely recommend periodic recheck examinations to assess how well your cat is responding to treatment. Blood work, x-rays, and echocardiographic examinations may also need to be repeated. In between veterinary visits, watch your cat for coughing, appetite changes, or changes in respiratory rate or effort and report any of these problems to your veterinarian.

    DCM is a relatively uncommon disease in cats, so even though a genetic component is suspected (for idiopathic DCM), predicting which cats will develop the condition is difficult. The best way to protect your cat from DCM associated with taurine deficiency is to feed a completely balanced feline diet that is adequately supplemented with taurine—most of them are. For cats with idiopathic DCM, regular veterinary visits and early detection of the disease may be the best ways to improve quality of life.