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Dog Heart Murmur Symptoms

| Updated September 26, 2017

Heart murmurs in dogs often have no significant health consequences, and don't negatively affect longevity or quality of life. In other dogs, a heart murmur may be a severe health issue and be the cause or the result of a variety of devastating health problems.


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The symptoms of a heart murmur in dogs overlap those of many other diseases, especially other types of heart disease. If these are observed in combination in a dog, consult a veterinarian for diagnosis and treatment. The symptoms may include coughing, lethargy, fainting, abdominal swelling, decreased energy and swollen limbs. Fainting episodes are the most dramatic and serious of symptoms that might indicate a heart murmur. A dog's owner may just notice something that seems unusual or abnormal about the dog's heartbeat. Immediate veterinary attention is important.


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A dog's heart murmur may be difficult to detect without a comprehensive veterinary exam. The process of diagnosis is similar to diagnosing heart murmur in a human. A veterinarian will use a stethoscope for the initial examination. A softer more sustained beat, rather than a normal short, steady canine heartbeat, indicates a murmur. Because many murmurs are very faint, the veterinarian may do additional testing. An electrocardiogram can measure the dog's heart rate to detect abnormal heart rhythms. Echocardiograms help detect disease of the heart valves and gauge the function of the heart. X-ray images can reveal abnormalities of the cardio-pulmonary system.


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Some heart murmurs indicate a life threatening condition. Others are insignificant. If an otherwise healthy dog does not present with serious symptoms like fainting, the veterinarian generally does not prescribe a battery of tests. A veterinarian may suggest observing a dog for escalation of symptoms. If any of the symptoms of heart disease appear, it becomes important to diagnose and treat the heart murmur. A heart murmur may indicate abnormal blood flow in the heart. This is usually caused by a change in heart valve function. Miscommunication between the heart's left and right sides can also cause a heart murmur. Heart valve dysfunction may be congenital or associated with age or disease.


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If a dog is diagnosed with a significant heart murmur, the veterinarian determines treatment based on the problem's severity and cause. Puppies born with congenital murmurs are often not treated unless they have accompanying health issues. Congenital heart murmurs often disappear as a puppy develops. It may take years to determine if a dog's heart murmur indicates a serious health issue. In many cases, no treatment is necessary. If heart murmurs do not subside, and if symptoms become debilitating, the veterinarian may recommend heart surgery.


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General health care is the best prevention of heart murmur and associated heart disease in dogs. Weight control is the most important preventative measure for heart health. High quality dog food, containing carnitine, taurine and omega 3, can contribute to cardiac health. A veterinarian may suggest supplements for a dog whose diet lacks in key elements. Regular veterinary health exams, dental cleanings and prescription heartworm preventatives all help to maintain cardiac health in a dog.