Feline Hypertrophic Cardiomyopathy – Symptoms and Diagnosis


  Cardiopathic cats may be asymptomatic or present with heart murmurs and/or arrhythmia (a common galloping rhythm).
In moderate to severe cases, other symptoms are also present: weakness, dyspnea, accumulation of fluid in the chest or lungs (pulmonary oedema), resulting in severe dyspnea, fainting.
In the case of thromboembolism caused by heart disease, partial or complete paralysis of rear limbs may occur if the clots enter the iliac artery or paralysis of the right anterior limb if the clot closes the right subclavian artery.
In this case, the diagnosis is clinical and, in addition to the paralysis, symptoms such as cold limbs, lack of pulse, pallor or cyanosis of the lining, muscle contractions with severe pain are also present.

Versamento pleurico

Reperto anatomopatologico

Reperto anatomopatologico


  Echocardiography remains the primary diagnostic and monitoring tool for pathology and/or patients at risk of HCM. The ultrasound image shows the early stages of disease (invisible in X-ray), and allows to accurately estimate the change in size of the whole heart and its individual structures. It also enables to assess the presence of asymmetrical septal proliferative changes, the condition of papillary muscles (often changed when we are dealing with severe cardiomyopathy), and to determine possible blood flow disorders,

The most important is the dimension of intraventricular septum (IVS) and left ventricular free wall (LVFW). In diastole they should not be thicker than 5mm (in large cats up to 6mm).

Depending on the type of myocardial hypertrophy, symmetric (both SIV and PL), asymmetric (only SIV or PL) or zonal (if only some segments of SIV wall or papillary muscles are affected) hypertrophy can be recognized.

Standards for the examination of cats’ echocardiography:

  • IVSd: 2.8 – 4.9 mm (cat 4 kg)
  • IVSd: 3.1 – 5.4 mm (cat 6 kg)
  • LVFWd: 2.8 – 4.8 mm (cat 4 kg)
  • LVFWd: 3.1 – 5.4 mm (cat 6 kg)

During the examination the doctor also pays attention to possible papillary muscle thickening.

Considering the dimension of intraventricular septum (IVS) and left ventricular free wall (LVFW), cats are classified as having a diastolic HCM:

  • Normal: up to 5.5 mm
  • Limit: 5.5 – 6 mm
  • Mild: 6 – 6.5 mm
  • Moderate: 6.5 – 7 mm
  • Severe:> 7 mm

   Echocardiography can also assess the degree of diastolic dysfunction, possible presence of dynamic aortic stenosis in the interventricular septum, mitral valve and SAM regurgitation, left atrial dilatation (less frequently bilateral) and echo presence, spontaneous contrast (“smoke” which predisposes to thrombosis due to high platelet aggregation in cats), volume and pressure overload.

HCM Gatto

Cardiomiopatia Ipertrofica Felina

Formazione di un trombo al livello dell’atrio sinistro

Profilo diastolico da alterato rilasciamento LA 1


Cardiomyopathy (Latin cardiomyopathia) – a group of myocardial diseases caused by various reasons (heterogeneous etiology) leading to abnormal heart function (dysfunction). Myocardial involvement may be accompanied by abnormalities in the structure and function of the pericardium, endocardium, other organs.
Cardiomyopathy is generally a heterogeneous group of myocardial diseases associated with structural and functional (electrical) changes.
They are divided into:

  • basic idiopathic (DCM, HCM, ARVC, non-classified cardiomyopathy)
  • secondary (related to other coexisting diseases).

  Over time, their diagnosis has become increasingly accurate thanks to the evolution of ultrasonic devices and the introduction of new diagnostic techniques such as the Holter test.

Instrumental tests

  • The ECG result, in the course of cardiomyopathy, may be normal or may show a deviation to the left of central electrical axis of the QRS complex or a left atrial blockade. Holter’s examination may help to detect supraventricular tachycardia (usually atrial fibrillation) or ventricular tachycardia if it is not detected in the primary ECG.
  • Radiographic examination is useful for the assessment of cardiomegaly, congestion and pulmonary oedema, pleural or abdominal exudate.
  • Biochemical markers (natriuretic peptides) may be useful as a diagnostic aid in unclassified cardiomyopathies but are not commonly used in practice.

Echocardiographic examination remain the gold standard technique remain in the diagnosis and monitoring of cardiomyopathy.
If the presence of concentric left ventricular hypertrophy is detected in hypertrophic cardiomyopathy, the left ventricle restrictive cardiomyopathy is almost normal but more stiff. The stiffness of myocardial cells may result from the dilatation of the left atrium or both. In dilated form, the cells also appear hypokinetic.
This form may be seen as the final evolution (“final stage”) of other cardiomyopathies.
It is characterized by impaired susceptibility and ventricular diastole, caused by stiffness with normal systolic function and myocardial thickness. Myocardial stiffness may result from various causes such as scarring, fibrosis and accumulation of abnormal proteins (amyloid) and other substances in the course of metabolic and muscular diseases. Restrictive cardiomyopathy accounts for 5% of all cardiomyopathy