| Clinical signs associated with heart failure are typically distinct, depending on the etiology of the heart failure, as well as the chamber affected. Some species variation also occurs. |
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Left-sided Congestive Heart Failure: |
| With left-sided CHF, clinical signs are associated with an increase in pulmonary venous and capillary hydrostatic pressure (ie, a back-up of pressure in the vessels delivering blood to the left ventricle). Pulmonary edema and congestion (cough, dyspnea) are the most common signs. Cats less commonly demonstrate cough; however, dyspnea, tachypnea, anorexia, or exercise intolerance may be noted. In cats, as in humans, increased pulmonary venous pressure can lead to pleural
effusion. This phenomenon is less common in dogs. Many dogs with left-sided CHF, especially secondary to degenerative valve disease, demonstrate syncope resulting from activation of the ventricular mechanoreceptors with a consequent surge in vagal tone and withdrawal of sympathetic tone resulting in bradycardia, hypotension, and collapse. |
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Right-sided Congestive Heart Failure: |
| Right-sided CHF results in an increase in pressure in the vessels delivering blood to the right ventricle—the systemic veins and systemic capillaries. This can result in ascites, pleural effusion, and/or peripheral edema. |
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Biventricular Failure: |
| This can arise when both the right and left ventricles are dysfunctional, such as in patients with myocardial failure resulting from dilated cardiomyopathy or toxin exposure. Clinical signs attributable to both forms of CHF can be noted, although commonly signs of one will predominate. |
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