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Canine Valvular Insufficiency and Congestive Heart Failure

29 14:13:36

Valvular insufficiency occurs when damaged and thickened valves
develop within the heart of small and midsize dogs. Valve
problems are unusual in larger breed dogs and in cats but they
may develop. In the small breeds of dogs, valvular insufficiency
begins in midlife and progresses slowly.

The disease is associated with thickening and shortening of the
valve components that separate the upper (atria) from the lower
(ventricles) parts of the heart. Remember, normally blood flows
in only one direction. If the valves fail to close completely
when the heart contracts, blood moves forward but some leaks
backward. Clinical signs vary depending on whether the right
and/or left side of the heart is affected and whether heart
enlargement presses on the windpipe. Fluid accumulates when the
heart fails to pump enough blood to the body and instead the
blood is transmitted backward from the heart to the lung or body.

Owners of pets with valve problems see inappropriate panting,
heavy breathing, diminished exercise ability, fatigue, cough,
and occasionally fainting. The cough usually starts at night and
progresses to daytime as well, particularly when associated with
exercise. Retching and nonproductive gagging follow the cough.
When the right side of the heart is affected, fluid may
accumulate around the lungs, making it difficult to breathe, and
in the abdomen, making it swell.

Abnormal heart sounds heard with a stethoscope suggest the need
for an electrocardiogram (ECG) to identify heart enlargement or
irregularities of the heart’s rhythm. Radiographs (x-rays) can
demonstrate heart enlargement and/or inappropriate fluid
accumulation. Blood testing can identify hormonal, kidney, or
other internal medical problems. An ultrasound examination
(echocardiography) accurately pictures enlarged heart chambers,
abnormalities of valve structure, and the heart’s pumping
ability. These tests assess heart function and severity of the
disease and identify the need for therapy.

A number of treatments are used for pets with valvular heart
disease, including exercise restriction. Walking is good
exercise. Digitalis is a medication used to strengthen the heart
and to treat some irregularities of its rhythm. It maintains a
slower and more effective heart muscle contraction. Signs of
digitalis excess include loss of appetite, lethargy, vomiting,
and diarrhea. ECG monitoring permits the veterinarian to
supervise the pet’s progress.

Diuretic agents are commonly given to remove excess water
accumulation from the body and can cause increased water
drinking and urination. Diuretics can induce weakness,
dehydration, and blood salt abnormalities. Alterations in
electrolyte (salt) levels are identified through periodic
testing of the pet’s blood. Angiotensin-converting enzyme
inhibitors (ACEIs) are drugs that improve the body’s ability to
reduce salt and water retention, to reduce high blood pressure,
and to limit the effect of hormones that adversely affect heart
muscle. Given in excess, ACEI drugs cause malaise, blood salt
disturbances, loss of appetite, and possibly kidney damage.
Antiarrhythmic agents may be given to stabilize the cardiac rate
and rhythm. Drugs to decrease blood pressure and nutritional
supplements may be required for specific conditions.

In order to control the symptoms of heart failure, low-salt
(sodium) diets may be suggested. Excess sodium is normally
removed by the kidney, but this does not occur as effectively in
heart failure. Commercial low-salt diets, varying from moderate
to extreme restriction, are effective in preventing salt and
water retention. These diets are recommended only after heart
failure has been diagnosed. A modest reduction in salt intake
may be indicated before the onset of heart failure.

If the pet refuses to eat a commercial diet, low-salt foods can
be prepared by the owner under veterinary direction. It is
important to emphasize that mixing low-salt diets with regular
(high-salt) diets or feeding snacks high in sodium is not
recommended. Longevity and quality of life in dogs with this
disease vary with the severity of the valve damage and the
amount of blood leakage into the upper chambers of the heart.
Concurrent medical conditions, age, and the physical status of
the pet play a large role in determining the animal’s prognosis.
Clinical signs are progressive, and although they may be
decreased, they never entirely resolve. Medical therapy can
enhance the quality of life of the pet as well as increase life
expectancy.

Dogs with left-sided valvular heart disease treated with
medication and a low-salt diet have an average life expectancy
of about 9 months from the time heart failure begins. Abdominal
fluid accumulation and body emaciation are signs of right-sided
heart failure. Regularly removing the extra fluid may increase
life expectancy. Surgical replacement of the valves is not an
option in dogs at this time.

The above is general veterinary information. Do not begin
any course of treatment without consulting your regular
veterinarian. All animals should be examined at least once every
12 months.