Heart failure is a condition caused by an abnormality in the structure or the function of the heart. The failing heart is unable to pump normal quantities of blood to the tissues of the body. Often heart failure leads to fluid retention in the lung and the body cavities leading to the condition called “congestive heart failure.”

There are many causes of heart failure in dogs and cats, including: birth (congenital) defects of the heart, degeneration of the heart valves, heart muscle disease (cardiomyopathy), heartworm disease, diseases of the pericardium (the lining around the heart), and irregular electrical rhythms of the heart (arrhythmia).

Dogs of any age and any breed can develop heart failure. Many older, small breed, dogs develop heart failure from abnormal function of the heart valves as the valve tissue degenerates. The most common cause of congestive heart failure in cats is heart muscle disease (cardiomyopathy), though anemia and uncontrolled hyperthyroidism can also lead to this problem.

Heart failure affects your pet by reducing the amount of blood that is pumped to the muscles, leading to fatigue. In addition, most cases of heart failure are associated with accumulation of fluid (edema) in the lungs, the chest cavity (pleural effusion), or the abdominal cavity (ascites). This fluid accumulation can lead to shortness of breath and other problems such as coughing and difficult breathing.

Some of the symptoms of heart failure, and the progression of heart failure in a pet, are related to increased activity of the nervous system and to increased concentrations of circulating hormones (and related chemicals).

Watch for: coughing, shortness of breath, difficult breathing (dyspnea), weight loss and fatigue. Check with your vet if you feel that your dog may have this or any condition.