Diagnosing heart failure in 2010 (Proceedings)


Diagnosing heart failure in 2010 (Proceedings)

Nov 01, 2010

The clinical signs of canine and feline heart failure are limited, but they must be distinguished from pulmonary dysfunction and also systemic problems. Heart disease often results in secondary respiratory signs (e.g., coughing or dyspnea); conversely, disease of the lung or its vasculature can result in secondary right heart disease (e.g., cor pulmonale). It is rare to find in any individual instance all the signs and other abnormalities that may characterize a specific disease. More commonly, an animal will manifest only some of these signs, usually in a way that the clinical elements of the disease emerge over time rather than being grouped at the outset.

The definition of congestive heart failure is the failure of the left and/or right side of the heart to advance blood at a sufficient rate to meet the metabolic needs of the patient or to prevent blood from pooling within the pulmonary venous circulation.

Asymptomatic Heart Disease.

At this level, a cardiac murmur or an ultrasound diagnosis of heart disease has occurred, but clinical signs are absent. Re-evaluation is the standard, and medication is not required.

Mild to Moderate Heart Failure

Clinical signs of heart failure are evident at rest or with mild exercise and adversely affect the quality of life. Typical signs of heart failure include exercise intolerance, cough, an increased respiratory rate, dyspnea, and mild to moderate ascites. Home treatment is often indicated at this stage.

Advanced Heart Failure

Clinical signs of advanced congestive heart failure are immediately obvious. These clinical signs could include respiratory distress (dyspnea), marked ascites, profound exercise intolerance, or hypoperfusion at rest. In most cases, hospitalization is mandatory.


Cardiomyopathy is a disorder of the heart in which the abnormality lies within the muscle tissue (myocardium). A secondary cardiomyopathy is a disease that affects the myocardium secondary to infectious, toxic, metabolic, or other disease processes. The majorities of cardiomyopathies diagnosed today are of unknown etiology (primary or idiopathic) and are currently classified in the literature as representing the hypertrophic or intermediate forms.

Primary cardiomyopathies are classified according to their morphologic appearance:
     • Hypertrophic cardiomyopathy (HCM)
     • Idiopathic dilated cardiomyopathy (DCM)
     • Restrictive cardiomyopathy (RCM)
     • Unclassified cardiomyopathies

Secondary causes of cardiomyopathy include:
     • Nutritional (taurine deficiency)
     • Metabolic (hyperthyroidism, acromegaly)
     • Infiltrative (neoplasia, amyloidosis)
     • Inflammatory (toxins, immune reactions, infectious agents)
     • Genetic (hypertrophic cardiomyopathy is suspected)
     • Toxic (doxorubicin)
     • Hypertrophic cardiomyopathy (HCM)