Download Dilated Cardiomyopathy in Cats

Dilated Cardiomyopathy in Cats
Rebecca E. Gompf, DVM, MS, DACVIM (Cardiology)
BASIC INFORMATION
DESCRIPTION
Dilated cardiomyopathy (DCM) is a disease in which the heart
muscle becomes flabby and weak and the heart chambers dilate.
The heart cannot effectively pump blood to the body, so the cat
lacks energy and fluid may accumulate in the lungs, chest cavity,
or both. As the heart dilates, the valvular openings between the
chambers of the heart enlarge and the valves begin to leak, which
adds an additional burden on the heart. Abnormal heart rhythms
(arrhythmias) are also common, especially atrial fibrillation and
ventricular arrhythmias.
Causes
Taurine deficiency can cause a reversible type of DCM in cats.
Taurine is an essential amino acid that must be supplied in the food
of cats. Commercial cat foods are supplemented with taurine, so
taurine-deficient DCM is uncommon unless the cat is on a vegetarian diet, is fed exclusively dog food or a single kind of canned cat
food, or has a medical problem that interferes with absorption of
taurine from the intestinal tract.
Idiopathic DCM occasionally occurs in cats, which means the
cause is unknown.
Clinical Signs
Signs often develop suddenly in cats with DCM. Some of the
early signs may be exercise intolerance, weakness, decreased
appetite, and cold feet. Increased rate and effort of breathing
(faster than 50 times per minute) may be the first sign noted by
the owner. If a blood clot becomes lodged in one of the front legs
or in both rear legs, those legs will be paralyzed and cold, with
blue foot pads. Your cat also may also be in pain if the clot happened recently.
Diagnostic Tests
Cats in severe distress often require stabilization before many
tests can be performed to evaluate the heart and other organs
(that depend on normal heart function). Tests may include the
following:
• Chest x-rays
• Echocardiogram (heart ultrasound)
• Electrocardiogram (ECG), especially if an irregular rhythm is
detected
• Laboratory tests to assess the kidneys, liver, blood electrolytes,
and taurine level
• Analysis of fluid removed from the chest
• Possibly abdominal x-rays and ultrasound studies
TREATMENT AND FOLLOW-UP
Treatment Options
If moderate to severe heart failure is present, the cat is often
hospitalized for stabilization with injectable diuretics (such as
furosemide), oxygen therapy, removal of fluid from the chest, and
other measures. After the cat is stable, oral medications are started
and may include the following:
• Furosemide (Lasix) diuretic is usually continued indefinitely
and may be combined with other diuretics.
• Angiotensin-converting enzyme (ACE) inhibitors, such as enalapril, benazepril, or ramipril, may be used to improve the quality
of your cat’s life and help reduce fluid retention in the body.
• Pimobendan is a newer drug that acts as a vasodilator to relieve
the workload of the heart and to increase the force of contractions of the heart. It is not yet approved for use in cats but
shows promise.
• Digoxin is used in some cats with moderate to severe heart
failure and very fast heart rates secondary to abnormal
rhythms, such as atrial fibrillation. Cats with DCM do not
tolerate digoxin very well.
• Beta-blockers and calcium channel blockers are used to slow fast
heart rates secondary to atrial fibrillation. They can cause weakness and worsen in heart failure, so they are used cautiously.
• Ventricular arrhythmias are often treated with atenolol and
sometimes sotalol, which are beta-blockers.
Cats with heart failure should not be fed salty foods, and lowsalt diets may be used to limit their salt intake. Some cats do not
like to eat low-salt diets, however. All cats with DCM are started
on taurine supplementation, because some cats with normal taurine blood levels respond to taurine supplementation. If the left
atrium is enlarged, medications may be started to prevent blood
clots from forming. Baby aspirin has been used for many years for
this purpose, and clopidogrel (Plavix) may also be beneficial.
Follow-up Care
Cats with heart failure are usually re-evaluated 7-14 days after discharge from the hospital. Chest x-rays, laboratory tests, and an
ECG are often repeated. Echocardiograms may be done every 2-3
months, and recheck visits are needed for the life of the cat.
Prognosis
Cats with taurine-deficiency cardiomyopathy have a good prognosis if they survive the first several weeks after being treated for
heart failure. Cats with idiopathic DCM have a grave prognosis,
with survival times of several weeks to months.
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