Congestive heart failure is the
inability of the heart to provide adequate circulation to meet the body’s
needs. It is the end result of a weakened heart muscle. The health of the
liver, kidneys, lungs, and other organs is impaired by the circulatory failure,
resulting in a problem involving multiple organs.
A diseased heart can compensate for many months or years without signs of
failure. When failure does occur, it may appear suddenly and
unexpectedly-sometimes immediately after strenuous exercise, when the heart is
unable to keep up with the body’s demands.
When and how to treat depends on the number of heartworms, their location, any
medical complications (such as congestive heart failure or
liver or kidney disease), the age and condition of the dog,
and the presence of circulating microfilariae. After a thorough medical
examination, your veterinarian will discuss these options and recommend a
treatment program based on the findings.
For dogs with uncomplicated heartworm disease, the objectives are to
eliminate all adult worms, kill the microfilariae
In toy and small-breed dogs, chronicvalvular disease
with mitral regurgitation is the most
common cause of congestive heart failure. In large-breed dogs it is dilated
The early signs of congestive heart failure are tiring easily, a decrease in
activity level, and intermittent coughing. The coughing occurs
during periods of exertion or excitation. It also tends to occur at night,
usually about two hours after the dog goes to bed. Dogs may be restless-pacing
instead of quickly settling down to sleep.
These early signs are nonspecific and may even be considered normal for the
dog’s age. As heart failure progresses the dog develops other signs, such as
lack of appetite, rapid breathing, abdominal swelling, and a marked loss of
Because the heart no longer pumps effectively, blood backs up in the lungs,
liver, legs, and other organs. Increased pressure in the veins causes fluid to
leak into the lungs and peritoneal cavity. Fluid in the lungs is the cause of
the coughing. A rapid accumulation of fluid in the small airways can cause the
dog to cough up a bubbly red fluid, a
condition called pulmonary edema. Pulmonary edema indicates failure of the left
With failure of the right ventricle, fluid leaks into the abdomen, giving
the belly a characteristic swelling or potbellied appearance (called ascites).
This may be accompanied by swelling of the legs (dependent edema). An
accumulation of fluid in the chest cavity (pleural effusion) also occurs with
right-sided heart failure.
In the late stages of congestive heart failure the dog sits with his elbows
spread and his head extended. Breathing is labored. The pulse is rapid,
thready, and often irregular. The mucous membranes of the gums
and tongue are bluish-gray and cool. A thrill may be felt over the chest.
Fainting can occur with stress or exertion.
An accurate diagnosis is established through chest X-rays, ECG,
echocardiography,and other tests (such as a heartworm antigen test) as
Treatment: It is important to correct any underlying cause whenever
possible. Heartworms, bacterial endocarditis,and some forms of congenital heart disease are
potentially curable if they are treated before the heart is damaged.
Treatment of congestive heart failure involves feeding the dog a low-salt
diet, restricting exercise, and giving appropriate medications to increase
heart function and prevent cardiac arrhythmias.