Cardiology Feline Conditions

Echocardiogram from a cat with hypertrophic cardiomyopathy. The left ventricular walls are very thickened and the chamber of the left ventricle is small.


Echocardiogram from a normal cat showing left ventricular walls that are normal in thickness.


Echocardiogram from a cat with hypertrophic cardiomyopathy. The mosaic colored jet is due to abnormal valve movement called mitral valve systolic anterior motion.


Xray from a cat with congestive heart failure manifested as pleural effusion (fluid in the chest).


                 2nd view


Echocardiogram from a cat with hypertrophic cardiomyopathy. The large chamber is the left atrium. The swirling is called spontaneous contrast and is thought to be a pre-clot phenomenon.

Hypertrophic Cardiomyopathy (HCM)

HCM is a disease whereby the heart walls become thicker than normal. This is the most common heart disease in cats and can eventually lead to congestive heart failure, clot formation, and sudden death. The asymptomatic phase can be years. There are many breed dispositions (e.g. Maine coons, American Shorthair, British Shorthair, Ragdoll, Persian, among others.) A genetic mutation responsible for HCM has been identified in the Maine coon breed.

Secondary hypertrophy of the left ventricle

Hypertension (high blood pressure) and hyperthyroidism (excessive circulating thyroid hormone) can cause the heart muscle to become thicker than normal in a similar manner to HCM. Treatment of the primary cause (hypertension or hyperthyroidism), however, can result in improvement in the heart disease.

Restrictive Cardiomyopathy (RCM) and Unclassified Cardiomyopathy (UCM)

Restrictive cardiomyopathy is a heart disease that is characterized by noncompliant heart muscle. The cause is not known. This disease can lead to congestive heart failure, thromboembolism (clot formation) and sudden death. Unclassified cardiomyopathy is a poorly understood heart disease that is characterized by normal appearing ventricular size and function and enlarged atria. This disease, like the other feline heart diseases, can lead to congestive heart failure, thromboembolism and sudden death.

Dilated Cardiomyopathy (DCM)

DCM is an uncommon cardiomyopathy in cats. DCM is characterized by poor contractility of the heart leading to enlargement. It can lead to congestive heart failure, thromboembolism and sudden death. A small percentage of cats with DCM are taurine deficient and supplementation can reverse the disease. If taurine deficiency is not present the prognosis is very poor.

Congenital Defects

Congenital defects in cats are less common in dogs. The most common of these are ventricular septal defect (VSD), tricuspid dysplasia and mitral dysplasia, however, other defects occur rarely.