Feline Hypertrophic Cardiomyopathy in British Shorthair

Feline Hypertrophic Cardiomyopathy (HCM) is a cardiac condition that often affects several cat breeds including Maine Coon, Persian, American Shorthair, Ragdoll, Bengal, and Sphynx. The importance of screening for HCM in British Shorthairs arises from past crossbreeding with Persian cats.

Etiology

HCM is characterized by thickening of the left ventricular wall and diastolic dysfunction. While the exact cause of HCM is not fully understood, a genetic component is recognized — often with an autosomal dominant inheritance pattern linked to specific breeds.

Illustration of a cat’s heart affected by HCM.

Clinical Signs

Common clinical signs include:

Respiratory changes such as pulmonary edema, rapid breathing, shortness of breath, and fatigue.
Coughing, sometimes mistaken for vomiting.
Acute signs like systemic arterial thromboembolism, fainting episodes, and sudden death in severe cases.
Other symptoms include lethargy, weakness, and loss of appetite.

Cat showing respiratory signs of HCM.

Diagnosis

In Brazil, echocardiography is the gold standard for diagnosing HCM. Recent studies also suggest the use of cardiac biomarkers like NT-ProBNP and BNP as complementary diagnostic tools.

Treatment

There is no cure for HCM, but treatment focuses on improving quality of life. The goals are to reduce heart strain, prevent arrhythmias and clots, and ease ventricular filling.

Common medications include:

ACE inhibitors: promote vasodilation and reduce heart workload.
Beta-blockers: lower the heart rate.
Calcium channel blockers: relax the heart muscle.
Diuretics: help remove excess fluids.

Cat receiving treatment for HCM.