Heart Murmurs in Cats

Picture of a cat with green eyes

What are heart murmurs, how serious are they, and why do they show up in our feline friends? If these are all questions you’ve asked yourself before, you’ll be happy to know that we’ll answer them all in today’s article. Keep on reading to find out more.

What Are Heart Murmurs, and How Are They Assessed?

If your vet hears a heart murmur when listening to your cat’s heart, it will be like a swishing noise. Heart murmurs aren’t necessarily pathological, but they aren’t normal, either. They are caused by a quantity of blood that is turbulent, and that is already in the heart or is exiting through the large cardiac vessels.

Most heart murmurs can be heard using a simple stethoscope.

This clinical sign is assessed depending on several degrees. There are several grades, from I to VI, with the first being the mildest and the second being the most significant one. These grades are not used to describe the severity of the heart murmur, however — merely how strong the sound is perceived by the person examining the animal.

There are a variety of cardiac conditions that don’t cause any heart murmurs at all, and that can put a cat’s life in danger. Still, there are several minor ones that do cause audible heart murmurs, and yet they can be relatively easy to manage with the right medication.

What Causes Heart Murmurs in Cats?

There isn’t just one factor that causes heart murmurs in our feline friends. First of all, the causes can be physiological (normal) or pathological (abnormal). Abnormal heart murmurs happen when there is an already existing cardiac health problem that needs to be diagnosed.

Unfortunately, there are many heart conditions that cause heart murmurs, and their severity varies a lot (especially since no veterinarian can tell just how good or bad of a condition your cat’s heart is in simply by listening to it).

Physiologic heart murmurs don’t have any negative impact on your pet’s health. They can show up in growing kittens and in adults that are very stressed and whose heart rate increases rapidly over a short period of time. Some cats can have heart murmurs when they are taken to the vet clinic due to anxiety. However, the murmur should disappear in this case if the heart rate returns to normal.

Physiologic heart murmurs have a lower intensity than their pathologic counterparts so they are graded from I to III or IV.

Pathologically, heart murmurs can be caused by structural (and functional) heart problems and by health problems stemming from other organs (of an extracardiac origin). Structural defects can vary a lot, but they all involve a somewhat abnormal defect that creates turbulence in the blood flow and, therefore, heart murmurs. The defect can be anything from a thick or narrow valve, an unusually large cardiac vessel, or a hole between the heart’s chambers. Every atrium and ventricle, as well as the aorta, has to be well separated in order for each to do their job properly.

Structural heart issues can be congenital or developed, with the first one being a defect that the cat is born with and the second being acquired during the cat’s life.

Several examples of extracardiac problems that can cause heart murmurs are anemia, infection, hypoproteinemia, obesity, and pregnancy. Anemia can be caused by a poor diet in adult cats, but in young kittens, it can also be developed as a result of severe parasite infestations.

How Is a Heart Murmur Diagnosed?

First of all, a heart murmur is a clinical sign, so it shouldn’t be the one being diagnosed — rather, the potentially pathologic issue that’s at the root of the heart murmur needs to be diagnosed. Vets can’t just prescribe cardiac medication merely based on what they hear using their stethoscope, and today’s technology has fortunately allowed us to use a variety of devices to reach a correct diagnosis.

Once the heart murmur is detected during the clinical exam, your cat will have to go through additional testing, which could range from an ultrasound of the heart (ECG) to an X-ray of the heart. Imaging methods can be particularly helpful, especially if there is a structural defect in your cat’s heart.

If an extracardiac health problem is suspected, your vet will recommend blood tests, which could show the level of protein, iron, and the number of red cells in your feline friend’s blood.

If none of these additional tests reveal anything in particular, the vet will recommend that you bring your cat in for a checkup several times in a row. As we have already mentioned, some cats can have heart murmurs due to high levels of stress, which could just as well happen during a clinical examination.

When It’s Serious

Serious cardiac health problems are usually associated with a number of other symptoms, not just the heart murmurs themselves. A cat that has any type of underlying cardiac issue that could be at the root of the heart murmurs, will exhibit weight loss, poor appetite, pale gums, lethargy, and even breathing problems.

By the way, cardiomyopathy can sometimes be misdiagnosed as a respiratory problem if the appropriate tests aren’t performed. Many cardiac conditions cause edema and difficulty breathing. If your cat has already developed pulmonary edema, treatment needs to be started right away. Otherwise, you might lose him or her.

Treatment and Prognosis

It’s practically impossible to say what the right treatment for a ‘heart murmur’ is since it’s a symptom and not the disease per se. Your cat will be prescribed heart medication depending on the condition that was diagnosed (using the additional tests we’ve mentioned above). Since with cardiac meds, one mistake can be fatal, you should ask your vet to give you detailed instructions on how you’re supposed to medicate your cat at home.

As for the prognosis, it depends on the severity of the disease that was diagnosed. Cats that have physiological heart murmurs have a very good prognosis simply because they aren’t associated with a medical condition per se. Cats with anemia can successfully be treated (of course, depending on the health status of the animal) with iron supplements and beneficial changes made to their diets.

Depending on the type of cardiac disease that is diagnosed, your feline companion might have to be monitored regularly so as to make sure that his/her heart health doesn’t get worse.



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