Cats are frequently diagnosed with heart murmurs, however hearing a murmur during a physical exam is no reason to panic. It is a reason to have a discussion about heart disease and what it may mean for your kitty. Many cats with heart murmurs will live long, happy, healthy lives and never need any treatment for their heart disease. For a select few, however, the murmur can be an indication that something more serious is going on. Further testing is warranted to determine whether treatment is recommended.
A heart murmur occurs when there is turbulence in the blood stream as it flows through the heart. The murmur is audible as a whooshing sound that occurs during the cycle of the heartbeat. Murmurs are graded on a scale of 1 through 6, based on intensity. A louder murmur indicates more turbulence, however it is important to understand that the grade of the heart murmur does not indicate the severity of the condition.
There are several conditions that cause heart murmurs in cats, some more serious and potentially life-threatening than others. Benign murmurs are generally low in intensity and don’t occur with other signs or symptoms that indicate a disease or illness. They are often referred to as “innocent murmurs”.
Cardiomyopathy—A common cause of heart murmurs in cats.
However, heart murmurs in cats are often associated with disease of the heart muscle called cardiomyopathy. Hypertrophic cardiomyopathy, the most common type of heart disease in cats, causes the muscular walls of the heart to thicken, decreasing the heart’s efficiency. If severe, these cats will develop heart failure, which is life threatening. Cardiomyopathy can also cause stroke in cats, which occurs when blood clots develop in the heart chamber due to increased blood turbulence. When clots enter the blood stream, they can obstruct arteries supplying the brain, hind legs, kidneys or lungs, resulting in paralysis, kidney failure, or even sudden death.
Although the cause of cardiomyopathy has not been clearly identified, the fact that the condition is more prevalent in certain breeds (including Maine Coon, Ragdoll, British Shorthair, Sphynx, Chartreux and Persian cats) and that mutations of several cardiac (heart) genes have been identified in some cats with this disease suggests that genetics plays a role.
What should you do if you cat has been diagnosed with a heart murmur?
To help determine the cause and the severity of the condition causing the heart murmur, there are several recommended tests:
- A complete blood and urine panel, including a Cardiac ProBNP hormone blood test is a great place to start. This will help us check for anemia, infections, kidney disease, liver disease, thyroid disease and other medical abnormalities that can cause or worsen heart disease.
- The Cardiac ProBNP is a simple blood test that checks for the presence of a hormone released as the heart muscle stretches, often due to being overworked from structural defect or damage. If there are abnormalities associated with the blood panel or ProBNP test, then further investigation is recommended.
- Simple, non-invasive and relatively inexpensive cardiac tests generally include blood pressure measurement, electrocardiography (ECG or EKG) and chest x-rays. Based on the results of the above tests and your cat’s clinical signs, more advanced testing, such as an echocardiogram (an ultrasound of the heart), Holter monitor and an evaluation by a veterinary cardiologist may be warranted.
An echocardiogram is an ultrasound examination that assesses your cat’s heart muscle and is the gold standard to obtain an accurate diagnosis of heart disease.
Although some cat owners decide to wait and do nothing other than observing their cat, this may not be a wise course of action. Cardiomyopathy can develop into a severe, life-threatening conditions very quickly, resulting in expensive diagnostic workups that sometimes yield poor outcomes. In general, we recommend performing an initial diagnostic workup for cats we diagnose with heart murmurs.