Our little felines, although they seem to be as usual when it comes to he alth, it may happen that they are diagnosed with a heart murmur in a routine check-up at the veterinary center. The murmurs can be of different degrees and types, the most serious being those that can be heard even without placing the stethoscope on the feline's chest wall. Heart murmurs may be accompanied by serious clinical signs and may indicate a serious cardiovascular or extravascular he alth problem causing those cardiac outflow consequences responsible for that abnormal sound on auscultation of a heart sound.
Keep reading this informative article on our site to learn more about heart murmur in cats, its causes, symptoms and treatment.
What is a heart murmur?
A heart murmur is caused by a turbulent flow within the heart or the large blood vessels leading from the heart, causing a abnormal noise that can be detected on cardiac auscultation with a stethoscope and that can interfere with the normal sounds "lub" (opening of the aortic and pulmonary valves and closing of the atrioventricular valves) and "dup" (opening of the atrioventricular valves and closing of the atrioventricular valves). of the aortic and pulmonary valves) during a heartbeat.
Types of heart murmurs in cats
Heart murmurs can be systolic (during ventricular contraction) or diastolic (during ventricular relaxation) and can be classified according to the following criteria to varying degrees:
- Grade I: audible in a certain area somewhat difficult to hear.
- Grade II: Quickly audible, but less loud than heart sounds.
- Grade III: Audible immediately at the same intensity as heart sounds.
- Grade IV: Audible immediately louder than heart sounds.
- Grade V: Easily audible even when just approaching the chest wall.
- Grade VI: Very audible, even with the stethoscope away from the chest wall.
The degree of the murmur is not always related to the severity of the heart disease, since some serious heart pathologies do not produce any type of murmur.
Causes of heart murmur in cats
Various disorders that can affect felines could cause a heart murmur and include the following:
- Anemia.
- Lymphoma.
- Congenital heart disease such as ventricular septal defect, patent ductus arteriosus, or pulmonary stenosis.
- Primary cardiomyopathy such as hypertrophic cardiomyopathy.
- Secondary cardiomyopathy such as that caused by hyperthyroidism or hypertension.
- Heartworm or heartworm disease.
- Myocarditis.
- Endomyocarditis.
Heart Murmur Symptoms in Cats
When a heart murmur in a cat becomes symptomatic or causes clinical signs, it may appear:
- Lethargy.
- Respiratory difficulty.
- Anorexy.
- Ascites.
- Edema.
- Cyanosis (bluish skin and mucous membranes).
- Vomiting.
- Cachexia (extreme malnutrition).
- Collapse.
- Syncope.
- Pparesis or paralysis of extremities.
- Cough.
When a heart murmur is detected in cats, its significance must be determined. Up to 44% of apparently he althy cats have murmurs on cardiac auscultation, either at rest or when the cat's heart rate increases. Between 22% and 88% of this percentage of cats with asymptomatic murmurs have cardiomyopathy or congenital heart disease with dynamic obstruction of the heart's outflow tract. For all these reasons, performing regular check-ups is so important, as well as go to the vet if you notice any of the symptoms of a cat with heart disease.
Diagnosis of heart murmur in cats
The diagnosis of a heart murmur is made by cardiac auscultation, through the use of a stethoscope or stethoscope instead of the feline thorax where the heart is located. If a so-called "galloping" sound due to its resemblance to the galloping sound of a horse or an arrhythmia is detected on auscultation in addition to the murmur, it is usually associated with significant heart disease and should be investigated thoroughly, with a full evaluation performed with the stable cat, that is, if it presented pleural effusion and the liquid has already been drained.
In cases of murmurs, tests should always be performed to detect cardiac or extracardiac disease that has consequences on the heart, so the following tests can be performed for the diagnosis:
- Chest x-rays to evaluate the heart, its vessels, and lungs.
- Echocardiography or ultrasound of the heart, to assess the state of the cardiac chambers (atria and ventricles), the thickness of the wall of the heart rate and blood flow rates.
- Heart disease biomarkers such as troponins or prop-brain natriuretic peptide (Pro-BNP) in cats with signs suggestive of hypertrophic cardiomyopathy and echocardiography cannot be performed.
- Blood analysis and biochemistry with measurement of total T4 for the diagnosis of hyperthyroidism, especially in cats over 7 years of age.
- Heartworm detection tests.
- Tests to detect infectious diseases, such as Toxoplasma and Bordetella serology and blood culture.
- Blood pressure measurement.
- Electrocardiogram looking for arrhythmias.
Is there a test to determine the risk of hypertrophic cardiomyopathy?
If the feline is going to be a breeder or is a cat of certain breeds, it is advisable to carry out the genetic test for hypertrophic cardiomyopathy, since it is known to derive from genetic mutations of some breeds such as the Maine coon, ragdoll or the Siberian. Genetic testing is currently available for known mutations only in the Maine coon and the ragdoll. However, even if the test comes out positive, it does not indicate that yes or yes you will develop the disease, but it does indicate that you are at higher risk. Surely as a consequence of mutations not yet identified, a cat that tests negative can also develop hypertrophic cardiomyopathy. Because of this, it is recommended that echocardiography be performed annually on cats with a pedigree with a familial predisposition to suffering from it and that are going to breed. However, due to the high abandonment rate, we always recommend opting for sterilization.
Heart Murmur Treatment in Cats
If the diseases are cardiac, such as hypertrophic cardiomyopathy, medications for the correct functionality of the heart and to control the symptoms of heart failure in cats, if it occurs, are key:
- Drugs for hypertrophic cardiomyopathy may be myocardial relaxantssuch as the calcium channel blocker diltiazem, beta-blockers such as propranolol or atenolol, or anticoagulantslike clopridrogel. In cases of heart failure, the treatment to follow will be: diuretics, vasodilators, digitalis and drugs that act on the heart.
- hyperthyroidism can cause a problem very similar to hypertrophic cardiomyopathy, so the disease should be controlled with drugs such as methimazole or carbimazole or other even more effective therapies such as radiotherapy.
- hypertension can cause left ventricular hypertrophy and congestive heart failure, although more rarely and usually does not require treatment if treated increased blood pressure with drugs such as amlodipine.
- If you have myocarditis or endomyocarditis, rare in cats, the treatment of choice is antibiotics.
- In heart diseases caused by parasites such as dirofilariosis or toxoplasmosis, a specific treatment must be carried out against these diseases.
- In cases of congenital diseases, surgery is the indicated treatment.
Since the treatment of a cat's heart murmur depends, to a large extent, on the cause, it is very important to visit the veterinarian to carry out a study and define the drugs that should be taken.
